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iATN Review: Newsletter for Members
Third Quarter 2012 EditionWorld's First & Largest Network of Automotive Professionals
Table of Contents
Introduction
2011 Chevrolet Volt Side Impact Campaign
MAF Testing 101
Impala Brake Bleeding
2003 Toyota Highlander Temperature Control
Diagnosing Intermittents
What to Do About Car Counts
Lambda for Diagnosis
Keep it Simple
No Communication With BCM
How Teaching Safety Became Important to Me

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This quarter we were overwhelmed with the number of great messages posted to iATN, and so this issue of the iATN Review is more jam-packed than usual.

Although you may not have serviced a Chevy Volt yet, we think you'll enjoy the thorough rundown, and accompanying photos, of the 2011 Chevrolet Volt Side Impact Campaign. MAF Testing 101 covers test techniques used when analyzing suspect Mass Air Flow issues. Impala Brake Bleeding details how a member was able to overcome brake bleeding issues found on late model Chevrolet Impalas. 2003 Toyota Highlander Temperature Control reviews what one member found when addressing climate control complaints, and how he was able to perform some board-level repairs rather than replacing major components (with documenting photos). Diagnosing Intermittents shares one member's strategy to successfully capture and identify an intermittent HVAC condition on a 2007 Pontiac Grand Prix. What to Do About Car Counts offers some insight into how to improve your repair shop's image. Lambda for Diagnosis is a great example of a really insightful response buried deep within a long discussion of things to consider when incorporating lambda into your diagnostic process. In Keep it Simple, a member describes how a young apprentice reached out to him for assistance concerning a vehicle networking issue. No Communication With BCM illustrates how one instructor bugged a vehicle and observed his students' processes to solve communication issues with a Body Control Module. Finally, in How Teaching Safety Became Important to Me, another instructor relates how an accident at his school has provided him with an extra incentive to focus on safety.

We hope you enjoy this issue and if you have a colleague in the industry you'd like to share this edition with, feel free to email them a copy or a link to read it on our site.

Regards,



Scott Brown
iATN President

Full Article


2011 Chevrolet Volt Side Impact Campaign
Technical Discussion Forum
James from Florida

2011 Chevrolet Volt, BATT/Charging/Starting Photo2011 Chevrolet Volt, BATT/Charging/Starting Photo
I thought there might be some interest as to the procedures used for the Volt side impact campaign. I'm posting some pictures of the last one that I did.

First, the battery removal.

[2011 Chevrolet Volt, BATT/Charging/Starting Photo]

Next, the high and low voltage connections and the coolant connectors on the battery.

[2011 Chevrolet Volt, BATT/Charging/Starting Photo]

The unmodified battery support tunnel.

[2011 Chevrolet Volt, BATT/Charging/Starting Photo]

The battery support tunnel with the new braces bonded and riveted into place.

[2011 Chevrolet Volt, BATT/Charging/Starting Photo]

The new and old coolant reservoirs with the new reservoir on the right showing the added low coolant switch.

[2011 Chevrolet Volt, BATT/Charging/Starting Photo]

Finally, the spliced in new wiring harness to connect to the new low coolant switch.

[2011 Chevrolet Volt, BATT/Charging/Starting Photo]

Full Article


MAF Testing 101
Technical Tips Forum
Kevin from Manitoba

2001 Toyota Camry LE, ECM/Inputs/Outputs Scan Data2001 Toyota Camry LE, ECM/Inputs/Outputs Scan Data
There has been a number of methods that have been discussed for testing under-reporting MAF sensors. Certainly having more then one method to test a MAF sensor adds extra tooling in your tool box. Here is a method I have found to work very well when checking a MAF sensor. This method is used once you have done some preliminary diagnosis and you are speculating you might have a skewed MAF sensor. The test involves graphing 2 Pids (STFT-Short term fuel trim) and (RPM) the test is done during light cruise speeds at gentle throttle tip In's below 3000 rpm. While monitoring the graphed data pids if the Short term fuel trim is mirroring the RPM I have found this indicates a skewed MAF sensor and will require replacement as this example shows

[2001 Toyota Camry LE, ECM/Inputs/Outputs Scan Data]

here is another example

[2001 Toyota Camry LE, ECM/Inputs/Outputs Scan Data]

Keep in mind the throttle tip In's must be made below approx. 3000 rpm otherwise the mirroring effect between the 2 pids will not mimic one and other. Here is an example of why this test must be done below 3000 RPM.

[2001 Toyota Camry LE, ECM/Inputs/Outputs Scan Data]

This method is a quick and simple testing procedure and I have found it simply allot faster then using a VE calculator and/or graphing numerous pids to examine after a test drive. However please remember using those other methods along with this one can certainly aid in conclusively determining if you have a skewed maf sensor... consider this method as adding another tool to the tool box.

Here is the after capture on the above vehicle with a new Toyota MAF sensor

[2001 Toyota Camry LE, ECM/Inputs/Outputs Scan Data]

Full Article


Impala Brake Bleeding
Technical Tips Forum
James from Florida

If you ever replace a brake master cylinder on a late model (2006-2012) Chevrolet Impala, get ready for some fun attempting to bleed the lines. The master cylinder sits below the BPMV and the lines rise upward from the master into flexible tubing and they run downward into the BPMV. Trying to bleed air from these lines is a very difficult job.

G.M. has a PIC5468A regarding this problem. They suggest that you loosen the lines at the master and rotate them downwards at the master before bleeding. Don't bother. The lines will still rise above the master at the point they fasten to the BPMV. I have seen techs spend hours trying to bleed these lines. I saw one tech unbolt the master with lines attached and suspend it over the engine with a bungee cord and use a pressure bleeder. Didn't work.

The only thing I found that will work is to first bleed the lines manually at the BPMV. Then I use an adapter from the brake flush machine to my mightyvac. I pump up 25 in. of vacuum and let it sit for 10 minutes then I pump the pedal slowly 30 or 40 times. Note - you will have NO brake pedal doing this due to the vacuum and the pedal will go easily to the floor. Repeat this procedure 3 or 4 times as necessary and it has always worked for me.

Full Article


2003 Toyota Highlander Temperature Control
Technical Tips Forum
Eric from Wisconsin

2003 Toyota Highlander, Photo2003 Toyota Highlander, Photo
Customer showed up with the complaint of not being able to set the temperature in her 2003 Toyota Highlander. Testing found a faulty climate control module (manual air/heat control unit). This is not a cheap part and the customers always question the cost.

I have seen this several times myself as well as a few times on the help requests. The replies on the help requests state to tighten the nuts up that are behind the temperature and air flow position control knobs. While this will help with the symptoms it is not the true fix.

The problem is caused by the loose nuts behind the knobs since this allows the control variable resistor to move around and break either the solder joint or wire(s).

If you are comfortable soldering small wires then the repair is relatively simple. Remove the climate control unit and separate it from the brackets that hold it to the radio.

Remove the eight screws that hold the back of the control unit in place and pull the back off. Disconnect the flat wire strip that connects the two circuit boards (there is no plastic connector on the end of the flat wire strip, it just pulls out).

Here is the back side of the temperature control knob and the two retainers that hold it in place. Remove the nut and washer from the front side of the control unit (under the knob). Using your finger, push on the front side of the temperature control while pushing one then the other retainer off to the side with another finger (no screwdrivers needed).

Now you have access to the circuit board for the temperature control. Carefully inspect it for broken solder joints and/or broken wires. As you can see, this one had a broken wire as well as broken solder joints. If you are lucky and just have broken solder joints just carefully reheat them with a tiny drop of fresh solder, reassemble, install and you are done.

With a broken wire you must remove the other wires from the circuit board using either a solder removal tool or a solder wick. Once the wires are removed, carefully strip them back. There is just enough extra wire to perform this repair once.

Now carefully prepare the solder pads on the circuit board by removing any excess solder. Make sure the holes are open and clean, otherwise you will have a difficult time getting the wires back in.

Insert the wires and solder them in place. Make sure to inspect the solder joints on the position control as well although I have only seen one that needed work there and that was just a broken solder joint. Install the temperature control circuit board, reassemble and install the control unit.

I have found that if the wires are broken it is easier to remove them from the larger circuit board and install a new set of wires. I solder them to the small circuit board first since it is easier to position it when the other end of the wires aren't connected to the larger circuit board. I purchased a roll of flat four wire at Radio Shack that works perfect. It is the same size as the original wires. I just cut a piece to length, pull off the extra wire, strip the ends and solder away.

One tip for working with screws in plastic. I hate finding broken or stripped threads in a plastic part. Each time a screw is screwed in place it cuts new threads, do that enough time and the hole strips out. I find that turning the screw backwards until I hear it click and feel it drop into the hold slightly gets the threads in the hole lined up with the threads of the screw.

Total time for a standard solder only job is less than 30 minutes (R & R included). If you have to replace the wire then I find it takes about 20-30 minutes more. Don't forget to charge twice your labor rate since you have no income from parts on this job.

I have done several Toyota Highlanders and would guess (but can't say for sure) that the other climate control units in the Camry and Corolla would be similar and may suffer from the same problem.

Full Article


Diagnosing Intermittents
Technical Tips Forum
David from Missouri

2007 Pontiac Grand Prix GT, ECM/Inputs/Outputs Scan Data2007 Pontiac Grand Prix GT, ECM/Inputs/Outputs Photo
I just wanted to share this story to allow others to see the importance of thorough diagnosis of electrical problems and to point out that sometimes the problem will be obvious if you simply take the time to look.

This 2007 Pontiac Grand Prix was on its third trip to the repair shop I work in, with the same problem that it came in for originally. The customer complaint was that the A/C did not work sometimes.

On the first trip, the tech simply operated the A/C for about 1/2 hour and wrote "No Problem Found" on the repair order after scanning and finding "No Codes Present" in the HVAC control module.

On the second trip, a second tech decided that it would be best to scan ALL modules, NOT just the HVAC module. This was an excellent idea, because what was found was a code "P0530 A/C Refrigerant Pressure Sensor "A" Circuit" which was located in the PCM. The HVAC module STILL said "No Codes Present" Exactly why that is...I do not know yet, but this proves what I have learned in diagnostic classes where I have been told that any diagnosis should begin by scanning ALL available modules.

The problem is that even though the second tech began correctly, he still did not complete the diagnosis. When he saw what code he had, he simply replaced the A/C high pressure switch and ran the vehicle out the door.

The third trip is where I got the vehicle. I scanned all modules and found that the same code was present that was found on the second trip. At this time, I did not even know that the vehicle had been there before or that any parts had been replaced. I was simply told "FIND the problem, whatever it takes..." I knew something was up, but I was not sure what.

So, anyway, the first thing I did after seeing the code was to look at the A/C high pressure sensor PID. I am looking at the thing with Key-On-Engine-Off and the sensor voltage is totally erratic. See the screen shot [2007 Pontiac Grand Prix GT, ECM/Inputs/Outputs Scan Data]

I could wiggle the wiring harness where it runs from the PCM and loops around by the cooling fan then goes towards the firewall near the transmission side pan and make the voltage remain steady or make it drop to zero and stay there. So I removed the air intake snorkel and the air cleaner assembly to get a better look at the harness. The FIRST thing I noticed was that the harness was rubbing against the high pressure A/C line and the pressure sensor itself. When I pulled the harness back, the problem was obvious. There were holes rubbed through the harness conduit!

So I disassembled the conduit, repaired 4 wires that had been damaged (one was the VREF for the high pressure sensor) and I fabricated a bracket from a piece that was laying around the shop. The bracket was fastened to the stud-bolt on the side of the transmission housing and the harness was zip-tied to the bracket to prevent future problems of the same nature. [2007 Pontiac Grand Prix GT, ECM/Inputs/Outputs Photo]

What blows my mind about this whole thing is that the first tech failed to scan all the modules and simply blew the customer off, and the second tech was RIGHT THERE and never LOOKED at the harness! He just threw a part at the code description! (which happens WAY too often)!

With times as tough as they are, customers cannot afford several trips to the shop - especially if it can be prevented by proper diagnosis the first time.

Full Article


What to Do About Car Counts
Shop Management Forum
Becky from Nebraska

The question of car counts and their importance to a repair shop has once again come up for discussion. A variety of opinions have been shared, some with better validity than others and far too many have been based on too little information from the person asking the question.

If your shop is in Detroit's inner city and your car counts are diminishing (well, duh), the worst thing you can do is to check the cars over better and work harder for upsells. This strategy assumes that you had too many cars before and didn't look them over well enough. This strategy assumes that your customers want them looked over.

Your problem is that your market is crumbling economically and you either need to close up and move, or figure out a better way to offer more value to the people that are left.

I present this situation simply to illustrate that good advice to some is not always good advice to everyone. It depends on where you are now.

Back to car counts. We have a great fast food place that started locally and has the best burgers, fries and stuffed bun sandwiches you've ever tasted. I've never had a burger that was as good as theirs and never been able to duplicate that great tasting beef at home.

At one time, there was another franchise across the street from them that was the classic early fast-food failure. The burgers were not very good and the fries were limp and greasy. Their sign out front nearly always advertised multiple burgers for a buck.

At lunch time, the line for the great food was long, the parking lot at the cheap food place was empty. Even though the price was cheap, the value was in paying more.

Let's take a quick look at the 4 kinds of buyers, probably started by Steve Donovan.

"A" customers--love their cars, want to keep them and take care of them. Failure to keep them up to date on things that need to get done will push them away. If their car fails to start because something was overlooked, it may cost you their business. These people are happy, well adjusted, generally make good money and have learned the value of planning ahead. They will call when it's time to do scheduled maintenance.

"B" customers--love their cars, don't always do the maintenance. They may not be aware of maintenance needs and can frequently be sold maintenance fairly easily. They may be leasing cars or trading frequently in order to avoid car repairs or to have reliable transportation. They can be educated about car care. They will schedule oil changes and will call for an appointment when problems develop with their cars.

"C" customers--don't know cars need maintenance. Might be young, may not have the money for maintenance. They'll drive in when they have a problem.

"D" customers--don't care if it leaks, squeaks, rattles or creaks. If it gets them from point A to point B, it's good. They'll have it towed in when it won't go any further.

None of these are good or bad, they're just different and each want different things. Understanding the difference is a key to marketing to them. Offering a cut rate oil change will almost never attract an A or B customer. Failure to check a car over will drive them away. Checking a car over for seriously poor people may repel them, because they can't understand prevention. They're always behind things financially, so prevention doesn't resonate with them.

If you want to attract a better clientele, start with 3 things that illustrate quality and WILL attract a better clientele, while at the same time REPELLING some undesirables:

SOAP, PAINT AND LIGHT--CLEAN the place so it's spotless. Floors should look like no one has fixed a car there before. Many drips and spills can be caught and cleaned easily by using drywall mixing tubs from the lumberyard stores. These tubs are about 2 feet by 3 feet and do a nice job. Each of our techs has 5 of them. One for each wheel and one kept clean to catch coolant that can be re-installed when performing cooling repairs.

PAINT the walls and ceiling white if possible. Clean and paint all shop equipment so it looks like it just came out of the box yesterday. Have a color theme if possible.

LIGHT the place so it's blinding inside. You should not need "trouble" lights to do brake work, undercar or engine work if you have proper lighting.

Take pictures of everything in your shop, from the outside to the bathroom, to underneath the work benches and the front office area. We all walk past things in our shops that may not look good and we get used to them. Pictures will help you better see what customers see.

This clean image will attract good paying customers with nice cars, nice clothes and nice jobs to your business. Those who seek something for nothing will not think that they are likely to find that at your place. They will drive on by.

This is a good start to improving your business and the best marketing that you can do.

The point about car counts is that if an increase attracts the wrong people, it's the wrong thing to do. If it attracts the right people, it's good. If we are going to increase the amount sold to each car owner, we need to understand what each owner wants. Offering a large list of needed repairs and maintenance to a "D" customer may drive them away. FAILING to offer the exact same list to an "A" customer will drive THEM away. There's nothing inherently wrong with "D" customers, many of them are great when they come in.

Understanding is the first building block of success.

Full Article


Lambda for Diagnosis
Technical Theory Forum
Robert from California

There are three issues to be clarified:

1. This is not an oxygen sensor. Any time anyone says it is, or implies that that is how it works, or that this is even its purpose is causing misinformation to be disseminated. And, what is worse, these exact sensors are used as real oxygen sensors in other applications - so it gets tricky as there is already information out there that can be used in conflict to their application as lambda sensors. In the presence of oxygen, they produce no voltage. In the absence of oxygen, they produce no voltage. It is only in the presence of combustibles and not enough oxygen to complete oxidation of them that they produce voltage.

2. In order to meet the conditions above, in a complex gas stream containing both combustibles and oxygen (and carbon monoxide and hydrogen count as combustibles - it is not just the fuel vapor) - the combustibles have to be a low enough concentration that the sensor's natural catalytic action can complete combustion enough to use up all the free oxygen in the gas mix. That is, the combustion has to run to completion in order for the sensor to create voltage in a rich mixture. (It only creates voltage in a rich mixture - oxygen has nothing to do with it.)

3. If the second condition above is not met, the sensor cannot accurately read the lambda state of the gas mix - and will respond in error. In the case of a bad misfire, the catalytic action of the sensor is not sufficient to complete the reactions, and no voltage is created. The ECU dumps more fuel in there until the catalytic action can use up the free oxygen is depleted enough for the combustibles to be sensed.

The idea that nothing will cause the voltage to go low except for oxygen is an odd way to look at a sensor. Sensors are only sensors when they produce a response. (An open wire, for example, also produces no voltage.) Voltage is created by the sensor only when oxygen ions flow through the sensor, and that only occurs when there is something pulling them.

My point is that stressing the absence of response is simply not the way to look at the function of a sensor - and will naturally lead to problems - as there are a multitude of conditions that will cause no response - but only one (for a good sensor) that will cause a response.

This is intended to be aa lambda sensor , and for a lambda sensor, there are only two important gas conditions:

1. Rich - excess combustibles. In this case, (as long as the chemical reactions can be run to completion) the sensor produces a voltage.

2. Lean - excess oxygen. In this case, (again, as long as the chemical reactions can be run to completion) - the sensor does not respond.

(There are those who insist that there is a third - that where the mixture is neither rich nor lean - the balance point of perfect lambda. While this is the theoretical ideal, in actual practice, it both never happens nor is it measureable. If the gas mix is perfectly in balance, and the chemical reactions can be run to completion, the sensor theoretically would produce no output.)

My points are two:

1. This is not an oxygen sensor, nor is it intended to be. (Even though this is a simple way to teach - it does not explain what is really going on - so you are bound to run into conditions where it does not behave as anticipated.) It is intended to be used to tell when the air/fuel mixture is rich.

2. The catalytic action is as important as the intrinsic mechanism of the sensor itself - as it only responds to a deficiency (a need for) oxygen in an equilibrium (chemical reactions completed) condition.

I know that there is a lot of discussion about this sensor - to the point of being absurd. However, it actually has a simple purpose and function, as is pretty easily understood - but not until the misconceptions are cleared away.

That is why I jump on posts that maintain the misconceptions.

Remember that Humberto's original question was a query about the Brettschneider formula - and the fact that he got high CO in (what he calculated) was a lean mixture.

This is an interesting case where both the lambda sensor (due to incomplete catalytic reaction) and the Brettschneider formula (due to the high level of HC concentration) fell apart - and both erred substantially in the lean direction - as the true mixture was quite rich (about 15% rich), but had really terrible combustion efficiency (about 55%, as I recall, as opposed to 95% normally).

So - the point is that even under pretty off-the-wall conditions, the theory behind both the Brettschneider formula and the lambda sensor hold up.

Enough said on my side, I think.

In essence, we all pretty much know how these things work - and are simply approaching the situation from our own perspectives.

Being in the gas analysis environment, though, I look at these topics in a global (any condition goes) sense, rather than just looking at one specific application - so my focus is pretty broad.

Best Regards,

Full Article


Keep it Simple
Technical Discussion Forum
James from Florida

One of the younger techs in the shop had a problem that seemed interesting today. The customer was driving down the road and heard a "pop' noise and all the warning lamps in the IPC came on, the gauges were inop, the A/C stopped working, the seats and windows were inop and the radio stopped playing. Other items may have been inop as well.

He scanned the control module system and had communication with only the ECM and the TCM. The ECM set U1301-00 and U1041-00. The TCM did not code. He asked me where he should go next. I told him to test resistance at the ALDL between 6 and 14 and between 2 and 4 with the key off after waiting 2 minutes. He said 6 & 14 had 60.1 ohms and 2 & 4 read open. OK - I told him next to pull the JX205 Class 2 splice connector and ck the resistance and pin fit on the purple wire from the ALDL to the splice connector. He said it was OK.

Hmmm - Next I told him to check each pin in the splice connector for resistance to ground. He said all had resistances in the kilohm to megohm range except pin H which leads to the rear body JX306 splice connector. He said this pin read open. OK, something isn't right here. Now I needed to walk over to the car and look for myself.

Pin H at the JX205 connector did read open. I then switched my DVOM to voltage and read a steady 6.92 volts. That's why he was confused that it read open with no Class 2 communications. I unplugged the rear splice connector and checked each pin for voltage. Pin A to the VCIM read almost 7 volts, full Class 2 voltage. Unplugging the VCIM, the voltage dropped to 0 and full communication was restored and all functions except OnStar was resumed.

The VCIM was back-feeding voltage into the Class 2 network even with the key off, causing the failure. He just didn't understand how he lost all class 2 communications due to an "open" circuit to one module.

Full Article


No Communication With BCM
Technical Discussion Forum
Martin from British Columbia

2008 Chevrolet Silverado 1500 LT, ECM/Inputs/Outputs Photo
It's been one of those weeks already. My students usually follow my instructions and directions in conjunction with service information, quite well. In many years as a technician, the only module that I had an issue with during diagnostics was when the old GM CAMS machine was hooked up. That is eons ago!

A more interesting aspect of something that went a little sideways yesterday was also worthy of discussion as follows.

Since we're looking at fuel supply of return and returnless systems, one of the ways to provide hands-on learning is to create some system failures that prevent the fuel pump from functioning. From some simple issues with fuel pump relay circuits to instill the fact that a relay socket can be a useful multi-purpose test location, to shorting the Hi speed CAN bus on the '07 Silverado C truck (current style GMT900). This is easily accomplished at the rear termination resistor on the bus, which is a simple plug in 121ohm resistor in a connector body [2008 Chevrolet Silverado 1500 LT, ECM/Inputs/Outputs Photo] as opposed to most other termination resistors that are inside modules.

With a couple of strands of copper wire wound across the resistor terminals, the desired no crank, no start, no communication issue was ready to go. Since the truck was at the end of the lot and the weather looked "iffy" with rain clouds looming, I swapped the resistor for a non-bugged one and drove the truck under the canopy at the shop entrance and reset the bug. Team "A" tackled this diagnosis while two other teams performed diagnostics on other vehicles. Being the coach and observer/evaluator, I move from one group to another leading, prodding and poking, to promote learning and critical thinking, at the point when floundering or a loss of forward direction is noted.

Back to team "A", they are usually pretty bright and an indicator of whether a given activity is reasonable for the level of learning that has taken place. They quickly discovered a loss of communications and performed straight forward bus diagnostics, determining that the High speed CAN bus lines were physically shorted together. They looked at the schematic and determined that opening a specific connector would separate the bus and may be useful in identifying where along the bus, the short was.

Once the connector was opened, communication to modules upstream was restored. This is a base model truck with only a relative handful of modules. A few minutes later, the installed fault was identified and rectified. I left them to verify the fix and reinstall the bug for the next team. However, I was quickly summoned back to the vehicle, where no communication with the BCM was being shown in other modules, no crank and no PRNDL. The team retraced every step, performed test after test and identified the bus measurements for resistances and voltage etc. All were in spec.

Their diagnosis identified a failure of the BCM, but I was not satisfied that just calling the BCM on these results is the final step. What could we do to go further without shelling out hundreds of dollars? How about stepping back and refocusing with a little thinking outside the box for a few minutes?

These students know full well that swapping modules can be asking for trouble, so that is not an avenue that they feel comfortable exploring. Let's assess the situation a little further. The network has been properly restored, no fuses have been blown, all connections to the BCM are secured and their claim is that they were never touched. However, I'm not nearly as gullible as they might think, since the BCM was removed from its bracket and left dangling during the bus diagnosis! After all, if they had not disconnected the BCM connectors, why was it not still clipped in its bracket?!

Let's re-scan the system and also focus on the low speed LAN, since the BCM is the gateway and active on both protocols. Hmm, its alive and healthy over on the low speed bus, no DTCs are stored anywhere. So, in summary, there should be nothing wrong, but only the BCM is not communicating on the HS, while modules downstream are just fine.

At this point, I'm inclined to suspect module lock up. So, just for the heck of it, the students disconnect the battery, remove the BCM, disconnect all seven connectors and verify no terminals are damaged. With all reconnected, the result is the same. At this point, the students are proclaiming their diagnosis to be accurate, but I'm still not giving in. We have another truck on the lot, a fully loaded 4x4 with the same BCM, but we're not supposed to swap modules are we?. However, what do we have to lose at this point?

One student proposes removing the module from the running truck and trying it in the non runner. Let's revise that approach just a little. If the non runner truck shows no indication of any other system failures than the BCM communication issue, what harm is likely to be inflicted by installing a non-communicating module into the running truck to verify the failure? With the BCMs ID'd as being the same P/N, I don't care if the truck starts or the module programming and setup is different. All I'm interested in is whether the BCM is able to communicate on the HS LAN bus. The students are prepared to take some measurements, but my directive is to see if the engine runs first. It fires right up with the proclaimed failed BCM!

Now the students want to take the other module and plug it into the non runner, but I have them reinstall the original back into the previously bugged truck and it fires up. Neither vehicle exhibits any DTCs and we have salvaged a BCM that in some way was simply "hung up".

In summary, I'm no advocate of "swaptronics", but I do like to exhaust all avenues before making the final call. I carefully weighed the options, the diagnostic steps that had been limited to using only a digital multi-meter, no blown fuses or other obvious component killers.

If you refer to the BCM replacement document 1741198, you will read precautions regarding module programming and setup, no start conditions and more, following a BCM replacement. Do such precautions scare you? I will always consider such statements, but take them under advisement. My approach to reactivating the class vehicle, did not put the donor vehicle network at any risk and in this case, thinking outside the box, saved the cost of a new box!

My recommendation is to think through unusual problems beyond the published information and be informed enough to weigh any risks based on prior testing and results.

There are many who will simply call a BCM failure, replace, reprogram, set up and move on to the next job quite happily. When you read posts by some of the current crop of "top guns" from independent shops or dealers do you realize or consider that these people are generally "think outside the box" types who do not simply "roll over" and accept published information as "gospel"? If you don't understand their way of thinking, step back and re-read some of their posts and learn how they come to some conclusions that you may be afraid to forecast. These individuals are accomplished performers, full of self-confidence in their abilities and system knowledge that goes well beyond published information.

Are you skilled and confident enough in your abilities to make judgement calls that allow you to accomplish every diagnosis successfully, or do you consider your diagnostic skills to be limited or inhibited by the quality of available service information? Believe me, there have been times during my career as a technician when I've been lucky more than skilled, but I was extremely confident that the outcome in this particular scenario was going to be a good one.

Regards,

Full Article


How Teaching Safety Became Important to Me
Educators' Forum
Tim from California

How teaching safety became important to me:

I retired at the end of the 2011 school year after teaching automotive for 38 years.

While reading an iATN thread about safety last year, I realized how much I had learned about safety, much of it while on the job. I really feel a need to share some of those experiences with other teachers.

I had been teaching for only 6 or 7 months when the only major accident of my career occurred. After I retired, I started sorting through some of the things I had accumulated over the years. One of the things I ran across was a deposition to which I gave testimony after that accident in which one student was seriously injured due to another youngster's lapse in judgment.

Here's my story. My 1st period class started at 7:30 a.m.. Even juvenile delinquents can be pretty subdued at that time of the morning and this was one of my favorite classes. I used to have lunch in the staff room with other teachers and staff. My vice principal, Buck Buchanan, was impressed because I had so many of his trouble kids in that class and during our frequent lunchroom encounters I often told him that I thoroughly enjoyed my group. They had lots of personality and I wish I had kept a log of all of the quirky things they did. For those of you who are old enough to remember, this was during the time of Welcome Back Cotter and these kids were my Sweathogs.

Things were progressing as normal that morning when shortly before 8 a.m. all hell broke loose. I had a top-notch senior who was working with a younger team member who for no apparent reason decided to turn the ignition key on a manual transmission car that was in gear with the clutch out. Remember, this was in 1973, before cars had the safety feature to assure the clutch was depressed before the ignition could operate. The car lurched forward, pinning the senior student between the vehicle and a workbench and giving him a compound fracture to his upper leg. Ill never forget the sound of his screaming; like a dog hit by a car. I had one of those moments where you hear about people having superhuman strength, pulling the car off of that kid and leaving tire marks on the floor.

A senior student from another of my classes was my tutor during first period. He was one of Buck Buchanan's high spirited kids and always seemed be in trouble in his other classes for one thing or another. He and I got along fine, however, and he was my hero on this particular day. We had no phone in the shop and there were no cell phones in those days. When I told him to get help, he literally jumped over a workbench and was on his way, sprinting quite a long way to the principal's office. The fire department arrived very quickly after that, but this young man had already run back to the shop to help me tend to the injured student.

The injured student was one of my favorites. He had signed up on a waiting list to be in the Coast Guard before he was 16, so he could follow in the footsteps of his father and older brother. This accident, however, disqualified him for service. I'll never forget visiting him in the hospital with his parents, his leg hanging in traction, when I learned that he would not be able to be in the Coast Guard. The accident was not my fault, but it occurred on my watch and I still feel some responsibility for the way this changed his life. Could I have done anything differently that might have prevented this accident? I don't think so, but it still haunts me.

One thing that really bothered me was that the school district did not have an accident policy to cover this young man's medical expenses and the family was forced to sue. This was my introduction to the craziness of bureaucracy. College prepared me in the many aspects of CYA. Fortunately, I had done all of the safety instruction and had kept records of each students safety test. After giving a deposition to a couple of attorneys hired by the school district, I never heard about it again.

This accident happened during my first year as a teacher. I was only 22 years old and was already supporting a family. Although I might have been wise beyond my years, I really didn't have any clue whatsoever regarding the nuances of my responsibility for the safety of my students. I was traumatized, to say the least, by the accident. But during my subsequent 37 years of teaching, this accident galvanized me to want to do my best to scare the crap out of my students so such a thing would never happen again while I was responsible for their safety.

I'm proud to say I made it through the rest of my career without anything more than a minor accident on my watch, but I was also very lucky. In one instance, during the year before I retired, I heard the sound of a lift lowering and instinctively looked away from my conversation with another student in the direction of the lift. The student had left a high reach tall jack stand under the rear axle of the car and was visiting with another student as he began to lower the vehicle. I yelled at him and got everyone out of the way in case the car fell. Luckily we were able to raise the lift back up without the car falling.

It is so important for a teacher to keep an eye out for everything that is going on! There were several other times during my career where I was able to prevent potentially serious accidents from occurring. But sometimes you are just lucky.

I have been in labs where I have observed teachers who immersed themselves in a single project while other groups of students are unsupervised. The more years under my belt, the more difficulty I had in watching a teacher who was unaware of the big picture. There are some really smart people who are sometimes oblivious to the world around them. Our students safety is our primary responsibility and you just cannot take this for granted.

I was very lucky to have an excellent teacher for a really engaging safety class during my upper division studies at Long Beach State. His name was Dr. Earl Smith and he became one of my mentors. We were required to write a safety test in his class and I really struggled with that. My room mate, a wood shop guy, had it so much easier; they lose fingers and have table saw kickbacks and other obvious stuff in wood shop. But, I had to write ten automotive safety questions and I had a difficult time coming up with them. From this end of my career, I have a hard time believing I was in that place because it all seems so obvious now. As a college student, I had lots of inert common sense, but I was making too many assumptions and had no idea what I was in store for as a shop teacher. Really smart people sometimes do the most careless things. Thomas Jefferson said that all men are created equal; however this refers to rights, not abilities.

Needless to say, the experience of having a serious accident in my shop really left a lasting impression on me. Since then, it has always been important for me to take pride in teaching real-world safety presentations, complete with stories. My intent was to scare my students with something they would not forget, but in a humane way.

For those of you who will be attending the NACAT Conference in July, one of the seminars I will be presenting will be on safety. I hope you can fit it into your schedule. I will explain how I teach safety in a way that keeps the students engaged. My presentation includes some slightly gory photos that I cannot include in the safety PowerPoint that I'll post on my web site, but I will provide some insights on how you can customize and personalize your own safety presentations.

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