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iATN Review: Newsletter for Members
First Quarter 2015 EditionWorld's First & Largest Network of Automotive Professionals
Table of Contents
Introduction
Pinpointing an Engine Mechanical-Fault Within Minutes
Swapping Global A Modules in G.M.'s
More Than One Way Find That Misfire
Charging System Diagnosis
Programming TPMS Sensor
Back Probe T-pin Modification
Another Pressure Transducer Case Study
Electrical Grounding
P1101 set in Cruze or Sonic
Online Advertising & Changes at Google
More HS CAN

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Happy New Year!

As we kick off the New Year, we're shifting the iATN Review to a more timely Jan/Apr/Jul/Sep release schedule. We're also excited about some new features we are about to release, though not quite ready to detail them just yet, so keep an eye on our news feed for more details coming soon.

Additionally, iATN will be at the ASA-Midwest 2015 VISION HiTech Training & Expo, March 5–8. Please stop by to see us at booth #229, and attend the iATN-sponsored reception Saturday night from 6–7pm. If you're an educator and not able to attend VISION, we'll be broadcasting the Educator Think Tank Panel Discussion (live) on Friday, March 6. Stay tuned to the Educators Forum for more details.

We have many excellent user submissions from last quarter that we're highlighting in this edition of the Review. All of the articles we selected were highly rated by iATN members, and we're honored to share them here. Topics range from pressure transducers, charging systems, and electrical grounding, to high-speed CAN, a heads up on P1101s in late model turbocharged GM products, and a very in-depth look at on-line shop marketing with Google.

Once again, we hope you enjoy this issue of the iATN Review.



Scott Brown
iATN President

Full Article


Pinpointing an Engine Mechanical-Fault Within Minutes
Technical Discussion Forum
Brandon from Florida

2013 Honda Civic Si, Engine/Propulsion Photo2013 Honda Civic Si, Engine/Propulsion Photo
I was presented yesterday with a 2013 HONDA CIVIC Si (2.4L). The vehicle was towed in due to a "stall/crank,no-start". We had a heck of a time getting it started but when we did, it would barely rev and missed terribly. Codes were cleared and none presented in the short time we had it running. I will note that during cranking the cadence exhibited sounds of at least one dead-hole.

Up until yesterday I have experimented heavily with pressure/vacuum testing to supplement after wards, what I have proven otherwise with more traditional-testing. I do this so that I may safely learn by starting with a conclusive answer and working backwards to make the correlations. Im pretty excited about this case-study because, as you will see, Ive proved to myself that I have indeed learned from "practice, practice, practice" and can rely on these advanced tests to yield me conclusive-info without the more invasive/traditional tests (no more "training-wheels").

I began my testing with a 2-trace scope capture of RELATIVE-COMPRESSION and a #1 IC-COMMAND. My waveform displayed a lack of compression on cyl #4 only. I then added the FLS to the mix and attached it to the brake-booster port in the Intake-manifold. [2013 Honda Civic Si, Engine/Propulsion Waveform]

[2013 Honda Civic Si, Engine/Propulsion Waveform]

If you refer to the captures, you can clearly see the problem. With these two captures alone (approx 10min of my invested time) and an overlay, I could conclusively tell not only that cylinder #4 was leaking but the intake valve wasn't sealing properly. More-Importantly, justified the need to tear the top of the engine apart for further inspection. (Take my word for it...the configuration of the engine requires removal of the cowl panel just to remove the COPs and Valve-Cover.) Upon removal, the evidence was clear (refer to the attached).

[2013 Honda Civic Si, Engine/Propulsion Photo]

#4 intake rocker-assembly has failed/fell apart. A "C-clip" that holds the assembly together became dislodged. This allowed the pivot pin to move longitudinally and jam itself against the cam-holder, holding one of the #4 intake valves off its seat ever so slightly. [2013 Honda Civic Si, Engine/Propulsion Photo] [2013 Honda Civic Si, Engine/Propulsion Photo]

With the Rocker-Bridge assembly and both camshafts removed from the cylinder head, confirmation of the #4 intake valve's integrity was confirmed. It sustained no damage. Replacement of the #4 intake rocker-assembly was the only new component fitted to the engine and upon assembly, roared to life and didn't miss a beat!

This was the perfect opportunity to prove that learning this form of testing can save you boatloads of time and pocket-fulls of money. Please let me know what you think of the captures above and feel free to be critical...Im always looking to improve my delivery. (sorry about the photos...as you can see, I still need some practice with my presentation...

Full Article


Swapping Global A Modules in G.M.'s
Technical Discussion Forum
James from Florida

Having just read a post about swapping Global A modules, I see that most techs know that they shouldn't, but don't know why.

Global A vehicles use a vehicle specific environment identifier to prevent module swapping. Not all modules use the identifier. The IPC, EBCM, HVAC, SDM, and ECM usually always do. Each of these modules will have learned the digital identifier during initial configuration.

In operation, the BCM is the controller of the environment identifier. It sends the identifier over serial data as a challenge. The modules respond by comparing the internally stored ID against the ID sent by the BCM. If they match, the modules send the ID back to the BCM over the data line. Depending on programming, the BCM may have to see one or several incorrect responses from the modules to take action. At this point, the BCM will disable starting and the modules will set B3902 for incorrect identifier received.

When the modules receive a correct identifier after the problem is rectified, they are supposed to clear the B3902 and restore normal operation. In the real world, this doesn't always happen. The modules may lock on the incorrect ID and become permanently inoperable.

I have a 2013 Malibu with 110 miles in my bay right now. The HVAC, IPC, SDM and BCM are setting B3902 as current and the BCM is setting C0775. Guess what's wrong with it!

Don't mess with used Global A modules. It's a crapshoot that will come back and bite you!

Full Article


More Than One Way Find That Misfire
Technical Theory Forum
Brandon from Florida

2001 Acura Integra GS-R, Engine/Propulsion Waveform2001 Acura Integra GS-R, Ignition Waveform
Last-week, I was presented with a 2001 ACURA INTEGRA DOHC 1.8L (B18C1) exhibiting an intermittent misfire. The customer told me, the misfire is more noticeable during a steady-state cruise/70mph, although I can feel the misfire right in the workshop, but very infrequently. Surprisingly, "snap-throttle/brake-torquing" could not flush-out an ignition-misfire so out came the FLS/lab scope.

The 2 traces revealed a misfire intermittently occurring on cylinder #4, as seen in this trace.

[2001 Acura Integra GS-R, Engine/Propulsion Waveform]

I switched to an ignition-scope because it was the next logical/easy general-test to help guide me down a diagnostic-path. A "paraded" acquisition quickly revealed some secondary-leakage on #4.

[2001 Acura Integra GS-R, Ignition Waveform]

So an inspection of the "fairly-new" ignition cable was conducted. Nothing stood-out as a potential leak-point for a spark-deviation so the plug was removed as well.

The #4 spark plug was fairly oil-fouled. As a result, the porcelain insulator had cracked and allowed the spark to short intermittently (very-surprising, given the excess KV-DEMAND of the snap-throttle/ brake-torquing couldn't reveal the problem initially...his complaint was at a steady-cruise!!!). I was informed by the owner that he was aware of the oil-consumption and he planned to have the valve-guide seals replaced soon. A new set of plugs was fitted and the vehicle ran flawlessly. The car was returned to the owner and he experienced no more issues....for 2-weeks...

The vehicle returned today with a more steady-misfire at idle, although not as bad at higher RPM. A vacuum gauge revealed a slightly bouncing-needle. Again, the ignition-patterns were analyzed and #4 revealed an issue, however nothing like it did before! The ignition pattern appeared to have a very turbulent burn-line and when paraded, #4 Firing voltage was far-less amplitude then the remaining cylinders.....ugh-ohh.....this feels as though we are heading towards a mechanical-issue!( see the ignition-patterns below)

[2001 Acura Integra GS-R, Ignition Waveform] [2001 Acura Integra GS-R, Ignition Waveform] [2001 Acura Integra GS-R, Ignition Waveform]

I interfaced the vehicle, first with : *CH1(YELLOW)- #1 IGNITION-SYNC *CH2(GREEN)- FLS ON THE INTAKE MANIFOLD *CH3-(BLUE)- RELATIVE-COMPRESSION The engine was cranked and the info was captured. The waveforms were exhibiting an obvious compression-loss on cylinder #4. There was definitely a disturbance evident in the intake-trace. Rather than analyze the capture, I chose to simply move the FLS from the intake-manifold to the tailpipe. A very-evident issue was present in the exhaust stream as well. I uploaded the waveforms to PC so I could apply an overlay and begin to put all of the puzzle pieces together. ...SEE THE ATTACHED BELOW!

[2001 Acura Integra GS-R, Engine/Propulsion Waveform] [2001 Acura Integra GS-R, Engine/Propulsion Waveform]

There is definitely more than one way to skin a cat. Ive learned this from Greats like Albin Moore...As he says, he is always looking to put "THREE ARROWS IN THE TARGET". I realize that the diagnostic-path I chose with this vehicle was not necessary to draw a conclusion but I more-so wanted to demonstrate multiple-tests that backed-up my data to help me put the diagnostic-puzzle together. The more I use what I have learned from others in regards to ignition/pressure/vacuum-waveform testing, I can feel myself becoming more confident in my diagnosis'. The connection between the results of my testing and engine-dynamics is also far less of a gap. With a bit more practice, I can see these techniques becoming replacements for the more traditional testing that has served me well for years. As always I welcome all questions/comments/criticism...every opportunity for anyone to learn is what Im trying to generate with my posts...Thanks Fellas! -BRANDON-

Full Article


Charging System Diagnosis
Technical Tips Forum
James from Florida

F and L terminalF and L terminals
Today, a 2007 Silverado came in with a complaint of "Service Charging System" message comes on at idle at times. It did not come on for me after a 10 minute idle period. Charge rate was 13.85 volts after the long idle period. Scanning the PCM, P0622 was set as history. I unplugged the two wire connector and probed the F terminal with a test light to B+. The F terminal signal on the scanner went from 0% to 97%.

This would seem to indicate an alternator problem. How best to easily confirm it? I graphed the L terminal and F terminal scan data and saw this...

F and L terminal

The L terminal command is fine but the feedback from the F terminal is all over the place. It should never reach 0% with a running engine. I replaced the alternator and rescanned the terminals.

F and L terminals

Looks a bit better now, doesn't it?

Full Article


Programming TPMS Sensor
Technical Tips Forum
Todd from New Jersey

I searched the data base and could not find this one, so here goes. Vehicle came in with tire pressure sensor light on, not flashing. Reset all tire pressures, hit button in glove box, tire pressure light blinked 3 times and came right back on. Scanned for codes, I had a c2121 - no signal from transmitter ID1 in main mode.

Using my TPMS3, I checked all the sensors and had 2 dead left side sensors. Installed 2 new sensors, retrieved the sensor codes with the TPMS3 and tried to upload them. I got a "Transfer Failure" message. I was also not able to clear the c2121 and I had no code for the other dead sensor.

After trying multiple was to program (including manually entering the codes with the solus) and being unsuccessful, I found T-SB-0084-09, which states when using Techstream, if you get a loss of communication message while programming TPMS, jumper ALDL pins 4&13 with the key on for at least 30 seconds with the key on, then remove fused jumper, and proceed with programming.

I wasn't using a Techstream and I did not seem to be loosing communication with the module, but I figured it was worth a try. It worked like a charm. I was able to program the sensors and clear the codes from the module. Hope this helps someone.

Full Article


Back Probe T-pin Modification
Technical Tips Forum
Mike from Ohio

Pre solderFinished product
The T pin is one of my favorite back probe tools. I was first showed them by Bill Fulton years ago. While I don't believe he came up with the idea I really liked it. There are many brands of back probe devices for sale that are very nice. I like cheap when possible and the way I mutilate these things I'm not going to spend anymore than 20 bucks.

I take the humble T pin found in fabric stores all over. Back Probe

I wrap the wire around it. Pre solder

Solder it. Soldered

Cut off the T. T cut off

Install heat shrink and eyelet. Finished product

Its cheap, very easy to get into close places without shorting other T pins, and harder to loose.

I have made and given away so many of these over the years . Most people really like them and I hope you can find a use for them as well .

Full Article


Another Pressure Transducer Case Study
Technical Theory Forum
Mark from Ontario

2003 Chevrolet Cavalier LS, Waveform2003 Chevrolet Cavalier LS, Waveform
I was called to a general repair shop to help in diagnosing this vehicle. This vehicle had a very rough idle and hard to keep it running at idle. There was a code p0300 and po172 for running rich . Looking at the data and trying to keep the vehicle running with foot on throttle , the fuel trims were negative approx -18 LT and -10 ST. The map sensor was showing 2.5 volts with part throttle indicating this vehicle was exhibiting low engine vacuum and supplying to much fuel ,thus the negative trims. I did not see a vacuum leak and there wasn't an EGR to speak of. I did a cranking relative compression test with pressure transducer in cylinder 1.(fuel disabled) [2003 Chevrolet Cavalier LS, Waveform]. You can see number 1 cylinder is lower than the others. Here is another waveform zoomed in showing vacuum transducer pulses in red and exhaust pulses in green. [2003 Chevrolet Cavalier LS, Waveform] You can see everything is labelled:  EVO, EVC, IVO, IVC. When the intake valve opens for cylinder 1,  you can see the pressure drop nicely in the compression waveform.

However, running compression, its a different story. The running compression shown here [2003 Chevrolet Cavalier LS, Waveform] for cylinder 1 , shows the running compression high at almost 160 psi. Jumped timing chain or slack in chain? Zoomed in running compression shows more interesting tidbits. [2003 Chevrolet Cavalier LS, Waveform] Exhaust valve opens at about 15 BBDC which is kind of late. I find some interesting details here .Notice the intake waveform flat spots labeled.I know the timing chain has jumped because of high running compression on cyl1 and low running vacuum. This intake waveform (the shape of the flat bottoms) ,could this be slack in the timing chain? From the waveform , it seems like the intake valve closes and there is a flat spot (delay) then another intake pull? I wonder if this technique can be used to spot chain slack? Also note when number 1 intake valve opens, there is a negative pressure drop initially in the cylinder but after a short time with intake valve still opened according to vacuum wave, a positive pressure is increasing.Is this compression from another cylinder ?

Myself , I find the in cylinder pressure transducer and vacuum and ex transducers tell more of the story but, of course, it takes more time, especially if the plugs are buried. Thanks for reading.

Full Article


Electrical Grounding
Technical Theory Forum
Robert from Massachusetts

I stumbled upon a great video explaining how grounding of electrical systems really works. This applies mainly to AC power generation, house wiring, equipment wiring etc.

It seems that the auto industry is not the only industry where students are taught the wrong theory for years.

Electrical Fundamentals - Protection against electric shock [youtube.com]

Full Article


P1101 set in Cruze or Sonic
Technical Tips Forum
James from Florida

There have been problems with P1101 set in the Cruze or Sonic with the 1.4 turbo engine. Lean codes may also be set with possible rough running or idle surge complaints.

The problem is caused by unmetered air entering the engine through the PCV system. Several PI's have been published to address this problem. PIP5197 and PI0907B among others. The first place to check is the throttle position angle with GDS2. A normal reading at hot idle is 8-12%. With a failure, the number will be much lower, usually 0-1% although less than 7% may indicate a problem.

The first place to check is the PCV orifice external port on the top of the cam cover. Vacuum should not be present at the port, if so, the cover must be replaced. If not, remove the PCV tube from the intake manifold and tape off the opening. Do the angle readings increase to normal? If so, replace the PCV tube.

Now you need to inspect for the root cause of the failure. Look into the PCV port in the manifold for a small orange tip of the non return protruding into the passage. If this tip is not visible, the non return valve is either missing or not seated which has damaged the other components from excessive vacuum and the manifold itself must be replaced.

If your angle readings still have not returned to normal, there is still a possibility of porosity in the PCV passage in the cylinder head. Check the crankcase pressure at the dipstick tube. It should read from -11 to -18 in. of water. If the reading is higher, the cylinder head passage must be tested for porosity.

Full Article


Online Advertising & Changes at Google
Shop Management Forum
Larry from Utah

Be forewarned this is another long post, so grab a cup of coffee and read it only if you have the time. I want to help explain to iATN members what we've been doing that's helped our rinky-dink 3K sq. ft. 4-bay transmission shop go from $600K/yr. to $1.3M/yr. in only 3 years. This is merely an update to those activities, as Google, Bing, & Yahoo are constantly changing. This post was originally made in transmission-only forums and I thought it would be useful for those iATN members who are engaged in transmission repair. Here's my post:

I have multiple changes to report with Google that span multiple products and product lines. The only thing that ever stays the same at Google is change. The Y-gen & Millennials keep changing stuff while the old people (X-gen) oversee and coordinate what's going on.

First, I'd like to mention that when Google makes a change or comes out with a new product, they don't do a global deployment. They pick a small, manageable user base as a test bed or "sandbox" to see how users like it and more often than not, make tweaks and changes based on user feedback. Often they will slowly grow the deployment area until they feel comfortable enough to finally do a global deployment.

The first, and most important change (to me, at least) is Google Drive. For those of you not familiar with Drive, it's much more than cloud storage. It includes Google Apps which has a host of business apps that replaces MS Office and does a lot more. All of the Google Apps have been highly upgraded with much more functionality to make them more "MS Office-like" to compete with MS's cloud version of Office, Office 360. Before, the Google Apps were more like lite versions of Word, Excel, Powerpoint, Outlook, Access, and the other products that come with the full professional version of Office. Now, they are closer to being the same, due to Google Apps being more powerful. The entire suite of Google products being available on your Android phone is just the icing on the cake. We bought a Galaxy tablet, but we have learned that we really don't need it because there's nothing we can do on a tablet that we can't do on our Samsung Galaxy S4's. To us, the tablet is just another electronic device we'd rather not tote around.

On the storage end of Drive, I now have access to my 1TB of storage from my Android smartphone and tablet along with all of my Google apps. The one I use the most is Calendar because that's how we schedule work at the shop. Here's a short video that will explain what Google Drive can do now, a lot better than I can.

Meet the new Google Drive [youtube.com]

The very best change they made with Drive is that the price dropped 80%. I was paying $50/mo. for Google Apps for Business with 1TB storage ever since I used it to replace Office 3 years ago and it's now been renamed to Google Apps for Work and it's only $10/mo. per user! And get this: If you have 5 or more users, the storage space is unlimited. Goodbye hard drives.

Google Goggles have been in the works for years. Google Goggles has the potential to make bar codes, QR codes, and more, unnecessary just as voice recognition has the potential to make a keyboard unnecessary. Basically it's a picture search. You take a picture of a product, ad, book, business card, or perhaps sign or menu in a foreign language, or anything else you want more information on and Google does an automatic image search for more information or translates it if there's foreign text in the picture.

Google Goggles Experiment Video [youtube.com]

There's been a multitude of changes in Google AdWords over the last 6 months. Some of the changes started as long as 2 years ago, such as Universal Analytics. Google Analytics as everybody knows it, will be totally dead by Spring as those web developers who have not already voluntarily converted over from Google Analytics to the new Universal Analytics, will be forced to as Google will automatically convert those accounts over who have not already done so themselves. Old habits die hard and I feel the old name of Google Analytics will stick or maybe somebody will make up a new name like "The New Google Analytics", but the official new name is Universal Analytics. Here's the 4 big differences I see, although there's many more:

1. The same user using different devices won't get counted as a different visitor each time they visit as they were before. First visiting on your smartphone, then on your desktop when you get home will count as 1 new visitor and 1 returning visitor. Before, it was counted as 2 new visitors.

2. Easier cookie timeouts, and visitor exclusions. The default timeout for a tracking cookie is 30 minutes and you had to know JavaScript to change it before. Now it's a button you click, along with you can exclude IP addresses and websites that you don't want to count the data on, like your own IP address, employee's IP's, competitors, and etc.

3. Helps you understand how your customer interacts with various touchpoints instead of the historical last click attribution model. It integrates and follows users who make contact with your blog(s), YouTube channel, social media, website, and any other URLs you list in GA as touchpoint properties and even allows you to either link or import 3rd party (non-Google) data into Universal Analytics to see how much all these dimensions play a part up until the ZMOT for that all important phone call. See ZMOT Video:

The Zero Moment of Automotive Truth [youtube.com]

4. Enhanced Link Attribution-If you have more than one way for visitor to to get to another page, (2 different links on the same page that go to the same place) Universal Analytics can tell you which link got them to that next page, not that they merely went from point A to point B. For instance, if you have a button on your home page that takes the visitor to the "Contact Us" page, but on that same home page, you have a SiteSearch box to where if the visitor enters the search term "email address", it will also take them to the same "Contact Us" page, Universal Analytics can now tell you by which method the visitor went from your home page to the "Contact Us" page. This is very useful information to help tweak, adjust, and design websites for the best user experience possible.

Lastly, I'd like to comment to those shop owners who think they don't have time for this kind of stuff, this sort of work isn't important, or perhaps you can't afford it. Or maybe you can simply care less, who knows?

Google has multiple YouTube channels, as well as help websites to help anybody learn how to use AdWords, YouTube, or social media to help your business grow. One of the big shifts that Google has made is to start training business owners on how to be able to handle all their online advertising themselves, or have a key employee, wife, secretary, or anybody they trust handle this sort of stuff to where they don't have to pay an alleged "Google Guru" a large monthly sum. Google quickly learned there's a lot of "experts" out there that are giving Google a bad name and Google's way to confront the issue is through education. Here's a Google YouTube channel that Google developed strictly to teach business owners (and consultants) how to start using AdWords and develop an ad campaign:

Google Ads YouTube Channel [youtube.com]

You can also easily learn Google Analytics by watching short courses which are usually 10-20 videos of only about 2 to 4 minutes in length each with a short quiz at the end. If you pass the quiz at the end of a course, you receive a Certificate of Completion. Here's the 1st of a 16 video playlist for Google Analytics that gives a brief overview of the course:

Welcome to Google Analytics Platform Principles [youtube.com]

When you wished you had that 1 extra transmission job a week, or perhaps 2, think online advertising. And after you get your Google Adwords campaign(s) working, Bing/Yahoo conveniently have an import utility so that you can import everything out of Google Adwords and into MSN so that you don't have to reinvent the wheel all over again by designing a new Bing/Yahoo advertising campaign from scratch.

If you can read a manual or watch a video to help you learn how to fix a transmission, you can do the same to learn how to be at the very top of all the search engines in your market area like we are and have the phone ring! Soon, your mouse will become Like A Switch On The Phone To Make It Ring

If an old burned out transmission builder can do it, anybody can do it.

Full Article


More HS CAN
Technical Tips Forum
Martin from British Columbia

Data Bus Diagnostic ToolHS LAN going to sleep
This is intended for those who are interested in CAN Bus exploits.

Coming soon (possibly next week) to North American GM dealerships near you, is the GM "Data Bus Diagnostic Tool".

I had the opportunity to download the program via TIS2Web this week and try it out on a couple of vehicles. The vehicle of choice for this post is a 2014 Chevrolet Silverado 1500 4WD truck, into which faults were inserted to view the program in action. However, the vehicle itself is not the real focus, but the Data Bus Diagnostic Tool (DBDT) may be of interest.

The main intent of the tool is to assist technicians in diagnostic direction and proficiency.

Let's begin by identifying how the program is started once downloaded. Data Bus Diagnostic Tool shows the main features of the home screen. Not shown is a single cursor.

Rather than attempt to explain all of the features (and to be quite honest, I have not had time to explore the program extensively since my free time is a premium), what follows will be a basic program overview as an introduction.

Once downloaded via TIS2Web, the program is accessed via a desktop shortcut. When the window opens, a very simple screen is displayed with some selectable tabs across the header, selectable bus type with baud type identified and a row of control buttons across the bottom of the screen. Nothing will happen unless the green power button is clicked, at which point the button changes to a red X used to close the program.

The Data Bus Diagnostic Tool uses the MDI as the interface, so if GDS 2 is hogging the MDI, it must be disconnected to allow the DBDT to identify and utilize the MDI, which will be identified. No MDI

It is no create surprise that the speaker button allows the program to feedback an audible tone that sounds quite similar to the screech of a logic probe when used to test a data bus. There is an option to have the beeper tone present during the presence of a bus fault or when the bus is functioning normally. To the right of the display area tool bar, is the familiar system voltage sign. Note that the KOEO voltages were low; only because the truck has sat unused since early June, save for being moved once in a while.

The photos are annotated to be fairly self-explanatory, but if the MDI is not connected, or is assigned to another program as aforementioned, it must be connected to the DBDT. There is an option to select devices, so I have no idea whether alternatives to the MDI will work, since I have not had the chance to try any.

This photo demonstrates the program in action with the vehicle KOEO. Normal Bus Function Normal HS GM LAN (CAN) voltages

In subsequent screens a simple fault will be introduced, to see how quickly the program reacts to a failure. The various states and time stamps from normal to failures and back to normal function on the bus will be displayed. Bus Detected State

The fault was introduced into the circuit at the under hood fuse box, by removing fuse # 57, which is an ATC 3-Leg Micro Blade fuse, which happens to feed both the ECM and TCM. As expected and can be noted in this photo, Also noted in the next photo is the change in the bus signal. HS LAN Bus fuse 57 reinstalled ECM and TCM back on line

This was done a few times in succession with consistent results during both KOEO and KOER. Turning the ignition off, the bus voltage began stepping down and when the key was turned back on, the voltage immediately rose to normal. HS LAN going to sleep

Now, I'm not overly worried about "bricking" a module, since we have only experienced a single module failure in many years. However, the next photo A Failure depicts a real failure on the bus. While viewing the effect of the fuse removal and reinsertion, someone happened to open the driver's door and the Bus Hi voltage dropped to 0 volts, as can be seen in here in the Measurement screen Bus Hi at 0 volts and is verified in the Detected State screen. Bus State

All module communication with the tool was lost, while the truck still ran, although when the rpm was raised, throttle control resulted in unstable flaring.

The bus Hi voltage moved from an initially unstable state to 0 volts from this time until proper function was restored. Powering down the DBDT and once connected, GDS 2 would no longer read or decode the VINas it would normally in this photo. GDS 2 When entering the VIN # manually, no communication was the result. Letting the truck go to sleep had no effect and neither did disconnecting the battery and connecting the cables together. I was pretty sure that the issue was in the ECM, but I had to head home for the day, since this was all done well on my free time.

At 4:45 am this morning I disconnected the ECM [2014 Chevrolet Silverado 1500 LT, ECM/Inputs/Outputs Photo] and waited a few minutes, then reconnected the three ECM connectors. Subsequently, normal data bus function was restored as was viewed on the DBDT. Scanning the system with GDS 2, resulted in DTCs stored in many modules as expected Bus function restored, GDS 2 display , which were then cleared, as shown here. DTCs cleared

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