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iATN Review: Newsletter for Members
Second Quarter 2009 EditionWorld's Largest Network of Automotive Professionals
Table of Contents
2009 Moving Forward
P0336 excessive crankshaft endplay
Aftermarket Catalyst Terminology
Volt drop testing an ignition switch
The hidden message
New age no-start
02 Dodge Intrepid 3.5L coolant temp, slowly overheats
97 Toyota Camry 2.2L MIL Lamp on

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2009 Moving Forward
From: Scott Brown

Although none of us are enjoying the recent economic downturn, we have an advantage over others in our industry who are not yet members -- we have access to each other.

As a group, collectively helping each other, we're one of the greatest resources one could have access to in tough economic times. The forums are a great place to pick up new ideas and solutions for your business, whether it's in the front office or the back shop. In this, our second issue, we not only have some great technical articles that members have rated highly, we have some excellent shop management info to share as well. And we're just scratching the surface. Dig in and take advantage of the millions of years of experience you have available at your fingertips within iATN.

We all benefit when the best in our industry participate here. If your friends include top-quality automotive professionals who aren't yet iATN members, please consider inviting them. They can register to join iATN here. Sponsoring members can use our invitation system to invite friends who will then receive 30 days of access to premium membership features when they join.

We thank you for taking to time to read the iATN Review, and hope that you find the information helpful. An online version of this and past articles can be found under the resources section in the members only area. If you have any comments and or suggestions, we encourage you to provide us with feedback at support@iatn.net.

Best Regards,



Scott Brown
iATN President

Full Article


P0336 excessive crankshaft endplay
Technical Tips Forum
Thomas from Missouri

2000 Chevrolet Suburban 1500, Engine/Propulsion photo
This Suburban came in today mil on and running poorly with a complaint of no power. I scoped the CKP signal and could not make a decision based on what was seen in the scope capture so I decided to graph the frequency of the CKP signal and sure enough I caught a glitch and pulled the trigger on the CKP but upon the test drive it felt better at first but after some real power was required it acted the same way again and you can hear a little engine noise.

I did not save the first round of waveforms so back to the shop to have another look here's the CKP waveform under snap throttle conditions and it was easily produced at higher rpms in the bay and I was careful not to hit the rev limiter function of the PCM.

[2000 Chevrolet Suburban K1500, ECM/Inputs/Outputs waveform]

and here are the some snap throttle conditions only graphing the frequency

[2000 Chevrolet Suburban K1500, ECM/Inputs/Outputs waveform]

I had seen in the archives that there had been some issues with crankshaft endplay possibly causing this so I had a look.

Beginning measurement

[2000 Chevrolet Suburban K1500, Engine/Propulsion photo]

Ending measurement

[2000 Chevrolet Suburban K1500, Engine/Propulsion photo]

These measurements where taken from the back of the flexplate through the inspection hole using a prybar at the balancer. There was also a fairly recent looking oil leak coming from the rear main area and the spec for crankshaft endplay according to Mitchell is .002-.008 and we measured .066 . So the sensor itself was not bad but the crankshaft movement is causing the signal to flake out and I found the graphing function of my meter to a good job of showing where the root cause is.

I hope this can help someone

Full Article


Aftermarket Catalyst Terminology
Technical Theory Forum
Mike from the California Air Resources Board

Given the recent law changes in California and the posts, I thought it might clear up some of the confusion (or at least not add more to it) to explain some of the terms commonly used with aftermarket cats so it makes a bit more sense. There are some that are quasi-legal terms that are used by the cat regulations and then there are many that are marketing/advertising terms used by the cat manufacturers.

'CARB-approved' -- Should mean that the manufacturer has applied for and received and Executive Order (EO) number from CARB certifying that the specific catalyst model has meant the minimum criteria and been approved by CARB. The proof is an EO #. If it has an EO #, it has been approved. If not, it has not.

EO number -- Executive Order number. Just like other aftermarket emission controls that are not identical to the OEM part (replacement parts) such as intake kits, headers, add-on superchargers, etc, if the part has gone through the legal process to be approved for use in Calif, it gets an EO #. There is actually a document on-line for each EO # that describes the part, the testing that was done to confirm it was legal, and in the case of aftermarket catalysts, all the vehicle applications that the specific part is legal for. http://www.arb.ca.gov/msprog/aftermkt/devices/amquery.php

'EPA-approved'/'Federal-approved' -- A marketing term, not a legal term. It means nothing because EPA does not have an approval process whereby they review and approve catalysts. To be legal for sale Federally, there are rules but it is up to the catalyst manufacturer itself to decide their cats meet the rules and thus, are legal. There is no application submitted to EPA nor does anybody review it or issue an approval or anything like that.

'49-state legal'/ 'OBD II-legal'/'OBD-legal'/'OBD-compatible' -- More marketing terms. Again, outside of California, it is up to the catalyst manufacturer itself to decide if its own cats meet the Federal rules or not. The Federal requirements are quite simple--the catalyst must last for 25,000 miles and have at least 70% conversion efficiency for HC and CO and 30% (yes that's not a typo) for NOx. Lastly, the catalyst manufacturer must agree to warranty the catalyst for 25,000 miles including if the OBD system detects a bad catalyst in those 25,000 miles. These terms just mean the catalyst manufacter has decided on its own that its cats meet those requirements. It does not mean the catalyst will have high enough conversion efficiency to pass your state's IM tailpipe test (if you have one) or that it will keep the MIL off for a little while or a long while or that it really 'works' with the OBD system.

'50-state legal' --Another marketing term. CARB approves cats for use in Calif, the manufacturers self-decide for cats in other states. Clearly, if the cat does not have a CARB EO #, it cannot be 50-state legal since it won't be legal in Calif. A CARB EO # doesn't directly make a cat legal in other states but since it is solely up to the manufacturer to decide what is legal in the other states, they typically would decide that any cat that got a CARB EO # has to be good enough for other states. (And yes, that is a very reasonable assumption).

"Direct-Fit" -- A marketing term. Nothing in any regulation talks about direct fit or not. Typically, catalyst manufacturers use this to mean it is a bolt-up type part, not a cut and weld-in type part. It relates only to how the part is installed and doesn't mean a thing about its performance. It does not mean it is 'like the OEM' for catalyst performance or that it has been certified or verified by anybody.

"Universal" -- Another marketing term. The counterpart to 'direct-fit', universal typically means it is a cut and weld-in type part and only refers to the method of installation. Again, it does not mean anything about its performance (or lack of) nor about its legal uses (e.g., it doesn't mean it is legal to put on lots of different vehicles or anything like that).

I won't summarize the new rules again--there have been other posts on that. This link on our website does indeed have some other info if you are interested in the California changes: http://www.arb.ca.gov/msprog/aftermktcat/aftermktcat.htm

It has the label decoding that Chris already linked, some FAQs that we try to keep expanding, some installer tips, etc. for California-installers and shops.

The bottom line--when Randy or others ask about a Calif cat, they mean one with an EO and no matter what the sales guy on the phone tells you, if it ain't got an EO, it is not a CARB-approved cat that has gone through an approval process. If you hear direct-fit, think bolt-in installation but don't assume anything about how well the cat performs. If you hear universal, think weld-in but again don't assume anything about how well it performs or what cars it is legal on.

And, while the coverage is still not great, for those vehicles that do indeed have a CARB-approved cat legal for it, our testing has shown pretty good durability and conversion efficiency that makes me comfortable recommending them to consumers or installers as a reasonable alternative to OEM.

Full Article


Volt drop testing an ignition switch
Technical Tips Forum
Karl from Quebec

multimeter dual trace hookupvoltage drop testing, dual trace
This is one I fixed a month ago. The complaint was intermittent no start and several idiot lights intermittently lighting up.

After consulting my wiring diagrams,I decided to attack the circuit at the most accessible spot. I went for the underhood fusebox. [multimeter dual trace hookup]

I decided to setup a dual trace to show you exactly what a voltage drop is(not everyone knows).

This is a pic of what it looks like when the problem occurred. [voltage drop testing, dual trace] The voltage going into one circuit of the switch was 12.32v. Only 1.82v was going out under load. The difference in voltage between the two measurements is the "voltage drop", in this case, a 10.5v "voltage drop".

On this model, the instrument bezel is easily removed and gives access to the rear of the switch. [2000 Chevrolet Malibu, Ignition photo] While observing the dual trace setup, I gently pushed rear of the switch towards the front and the voltage drop disappeared. [no more voltage drop]

This is an internal view of the switch I autopsied. [2000 Chevrolet Malibu, Ignition photo] It uses a complex assortment of tumbler pins that apply pressure to superposed stainless "finger blade" type contacts. The whole thing appears quite cheap and flimsy, and I am not surprised they have a high failure rate.

Hopefully this will help some demystify what voltage drops are.

Full Article


The hidden message
Shop Management Forum
George from Nebraska

Oftentimes, a business will try to solve a problem by going about it the wrong way and end up hurting themselves without realizing it. In too many cases, new policies are set because of some strange experience with an extreme customer.

This has the effect of doing something that causes a negative effect on our good customers.

Let's take an example that I'm seeing more and more of. A simple, seemingly innocuous sign that keeps popping up, mostly at fast food places:

"Please present coupons at time of order".

Here's what this REALLY communicates to customers:

First off, you don't even HAVE any coupons. That means you're basically getting screwed because you're paying too much. The business obviously has them out there, but there's no way for you to get them now. You''re trapped in the line and have no way to avoid this. Boy, don't you feel good now about eating here. :o)

Second, if you do have coupons and don't follow the "rules", we're going to let you know how much trouble you've caused because you refuse to follow the "rules" like everyone else is supposed to. We'll be sure to send you on your way with our last contact being "you're a real pain to us". With the inexperienced, under-trained help we have, that will be easy to do.

Third, even though we designed our whole system, we choose to put the burden of our ineptitude on you, by putting up another hoop for you to jump through before we'll accept your money. Be sure to remember to do this right. Even though we could easily make it a cinch to take any coupon presented at any time, that's too easy. We'd rather seek an opportunity to rain on your parade.

Fourth, be sure your coupons haven't expired, even though they may have been good yesterday. We love to point out that it isn't good today if it's expired.

This last item has happened to me on numerous occasions. I'm not a coupon guy, as I don't like a bunch of paper laying around that I forget to use.

Walgreens is the master of all coupons. They always have a ton of little things on sale. On many occasions, a sales clerk has voluntarily searched through the coupons to see if they can get me any discounts and I haven't even asked. This is a very positive experience and Walgreen's business is booming.

At my shop, we don't say anything about coupons, ever. We always have an oil change coupon in our Newsletter, good for a few bucks off. We give everyone the coupon deal, even if they didn't present the coupon. When we do this, we always tell the customer we gave them the coupon price "since they presented the coupon", nudge, nudge, wink, wink. When they say they forgot it, I always say, "no, it fell out of your purse or pocket when you came in. You should be more careful", said as I smile broadly.

Any coupon presented at any time is easily handled by us. We simply go to the "discount" section of our software, punch in the amount and give them the new total. Easy as pie, handled with a smile.

I was in a small neighborhood grocery store and they had a little sign above the eggs, advertising a lower price "with coupon". I needed eggs, so I tried a little experiment. At the checkout, I told them I forgot to bring the coupon, could they give me the deal, anyway. NOPE, not without the coupon, was the reply. I then asked why they even had a sign up about the coupons. All it does is make people mad, me included at this point.

You see, it costs a lot of money to print and distribute coupons. This money is spent in an attempt to generate more business. If handled incorrectly, this practice can make people mad.

One of my favorite George Witt quotes is: "Don't spend money to make people mad. You can make them mad for FREE!"

Be very careful about signs, policies or procedures you implement in your business asking the customer to do something to benefit you. Better to understand that the general public tends to be a little scatter-brained and is probably going to do some things that drive you crazy. Just smile and deal with it politely, as this is truly the nature of the retail business. If you have trouble with retail, maybe you should seek another line of work, because people just aren't going to change, no matter how many signs you put up or policies you implement.

Full Article


New age no-start
Technical Tips Forum
Cale from British Columbia

2009 Chevrolet Tahoe, ECM/Inputs/Outputs scandata2009 Chevrolet Tahoe, Fuel Supply scandata
I had a broken vehicle the other day; I thought I would share some of the things I learned. This (as I'm sure you'll agree) was a very easy diagnosis. What I found interesting about it, is how much easier life is with newer vehicles in some instances. The way you attack problems is the same as before, but given all the scan data, codes, and bi-directional controls at your figure tips, diagnosis becomes much faster and less dirty. I realize that the following case study is in regards to a newer vehicle. A vehicle that most of you won't see until after the warranty period, but it should be a good pre-cursor as to what's coming down the line.

The vehicle is a 2009 Chevrolet Tahoe, with a 5.3L engine and 20,000 Km on the clock. It was towed into the shop. The complaint was "no-start". I rarely get any more info then that. The service writer has already decided that it needs a fuel pump :-)

The first thing I did was to try to start it. Guess what, the battery is stone dead. Luckily it's the end of the day anyways, so I put it on slow charge for an hour, and duck out early.

The next morning (with the battery fully charged) I again tried to start the vehicle. This time the vehicle cranks over smoothly, but will not start. I grabbed my scan tool and cleared all the "low voltage" related codes that resulted from the dead battery. After doing a little bit of reading I found out that this vehicle has a Fuel pump control module (FPCM). It also has a fuel rail pressure sensor. At this point I haven't opened the hood yet. With the Tech 2 I went into the FPCM data list, then cranked over the vehicle. This is what I see:

[2009 Chevrolet Tahoe, ECM/Inputs/Outputs scandata]

You'll notice that there is no fuel pressure, also the fuel pump command says "off". Obviously that's why the vehicle won't start. While I'm in the FPCM I selected special functions [2009 Chevrolet Tahoe, Fuel Supply scandata] and commanded the fuel pump to run:

[2009 Chevrolet Tahoe, Fuel Supply scandata]

As you can see it does build fuel pressure, the vehicle will now start and run for a couple seconds, then die. Next I check for codes in both the FPCM and the ECM:

[2009 Chevrolet Tahoe, ECM/Inputs/Outputs scandata]

[2009 Chevrolet Tahoe, ECM/Inputs/Outputs scandata]

Just so you know the other three codes in the ECM were caused by me later on.

Looking at the setting criteria for DTC P025A, there is an enable circuit that goes from the ECM to the FPCM. The ECM sends 12V down the enable circuit wire (Dg/W) when the ignition is in the on position. This circuit controls the two second prime as well as normal engine running conditions. The DTC sets when the serial data message from the ECM, does not agree with the enable circuit. Basically the FPCM is not seeing the enable circuit voltage. Now I might have to get down and dirty and actually test something. So I get one of the apprentices to raise the vehicle on the hoist. The first thing I have to do is dig out the FPCM as it's covered in snow:

[2009 Chevrolet Tahoe, Fuel Supply photo]

[2009 Chevrolet Tahoe, Fuel Supply photo]

Next I went into the ECM special functions and commanded the Fuel pump relay to on (this function will run the enable circuit).

[2009 Chevrolet Tahoe, Fuel Supply scandata]

[2009 Chevrolet Tahoe, Fuel Supply scandata]

I measured the voltage (on the enable circuit) at the FPCM and saw this:

[2009 Chevrolet Tahoe, Fuel Supply waveform]

I now know that the enable circuit is good. I checked the connector for water intrusion and it was dry. The only thing left to do is to order an FPCM. I installed the new FPCM, used SPS to program it, and the vehicle fired right up. I fixed this vehicle in late December. I see that in January GM came out with #PIT4784, which addresses this concern.


Full Article


02 Dodge Intrepid 3.5L coolant temp, slowly overheats
Chrysler Engine TechHelp
Denny from Pennsylvania

I have never seen this one before.There is no boil over or bubbling sounds; there is no sign of any problem, other than the temp. gauge slowly rising. I have bled the sys. over and over.I even lifted the left side to raise the tank higher than the motor, and bled the sys.; Watching the scanner, the temp. will go slowly as high as 247 F. Here is the strange part; if i turn the heater fan on full blast, the temp. will go right back down! Also, when the temp is high, the rad. fans are on full blast, but the water does not seem to be circulating through the rad.( fans are sucking cold air out of rad.). Has anyone seen this?

Thanks to all 42 replies! I took all into consideration, and looked at the water pump first... (You can read the full article, 43 replies, and FIX here.)

Full Article


97 Toyota Camry 2.2L MIL Lamp on
Asian Driveability TechHelp
David from North Carolina

This toyota was worked on at a friends shop and was sent to me for help. Car needs to be inspected. The list above tells the tale of parts that have been installed or tried. When I got car I test drove after clearing trouble codes for 30 miles. The car never missed or had any driveability problems.My friend also stated that he or customer ever feels a miss. While I was driving car I watched data and saw no problems. I am using a brick for scan tool on this vehicle with 2000 asian cartridge hooked to odb2 connector. Freeze frame data was very little. It said 2300rpm,coolant temp 179,and p0300. When I watched misfire data on scan tool,cyl 2 and 3 would show some misfires. After clearing codes and driving 30 miles,readiness codes for catalyst,02,evap were not ready. Misfire showed ready. When I test drove after clearing codes the cel began flashing first after about 5 mies and then came on steady. This is a convertor warning. Back o2 is switching frequently. I am wondering what criteria is for this. I also removed timing cover and double checked marks and inspected lower gear. All were right. Belt also was correct(round,square).I am at a loss... (You can read the full article, 15 replies, and FIX here.)

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