Service traction control light

Andrew from Midland Technician Posted   Latest  
Question
Network Communications
2012 Chevrolet Silverado 2500 HD LT 6.0L (G L96 Flex) 6-spd (1000)
Service Traction Control
U-0100-7F
Service Traction Control Light Comes On When You Rev The Vehicle While In Park Or In Motion
Fleet Truck
I Have Three Exact Same Make Model And Year Trucks With The Same Problem
The Only Code Stored Is U-0100-7F In The Ebcm
I Checked Powers And Grounds At Ebcm With 4 Amp Headlight Bulb. I Have 60 Ohms Resistance In Pin 6 And 14 On Dlc. Need Ideas On What To Check

I checked powers and grounds at ebcm with 4 amp headlight bulb. I have 60 ohms resistance on pin 6 and 14 on dlc. Need some direction on what I should test or check. I will try to load a file of the communications while the fault happens . I tried hitting hard bumps in roads Moving harness in engine bay and around bcm and no service traction control light. Only when you rev the engine and its intermittent. No apparent damage on harness that I can see. 

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James from Pike

 

Owner/Technician
 

Have you checked for excessive ripple from the alternator?

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Andrew from Midland

 

Technician
 

Didn't mention that on top but yes I was thinking the same but wave form was good . I tested it at idle with no loads or under acceleration not sure if that would change the outcome of the ripple test

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Geoff from Lahaina

 

Diagnostician
 

Off-the-cuff I would say check for alternator ripple, and check for excessive noise from a (bad) ignition coil.

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Andrew from Midland

 

Technician
 

How would I check the noise coming off a coil. Is it the control wire going into the coil or use an ignition pickup clamp on the spark plug wire. 

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Geoff from Lahaina

 

Diagnostician
 

Scope the grounds, zoomed-in, and look for a huge spike that mirrors an ignition event. Some noise is OK/normal but see if you see a huge spike before the MIL sets. That EMI will be everywhere under the hood. Many stories of one bad coil causing crazy issues, maybe yours is another one. This is not quite your issue, but I made a short video the other day about watching the grounds to find a missing ignition event; youtube​.​com/watch?v=MUr2YD…

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Maynard from Elmira

 

Technician
 

I am not sure what the definition is of that code, but I see it is a communication code. I have learned that when there is a CAN communication bus problem.... the first distant early warning telltale to the driver will be the TRAC light or traction disabled message on dash. Then you may find U codes in one or more modules, and the problem can be kinda anywhere on the network, not specifically where the codes are stored in and so on. What may be helpful is to use the GM BUS Diagnostic tool, drive around until the problem presents itself then quickly look at the modules reported as being online, compare that list against one when there is no problem currently present. This can give you an idea as to where a break in the network is occurring.

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Chuck from Jacksonvilee

 

Diagnostician
 

are all 3 trucks fleet vehicles? 

Do they have any tracking or data monitoring components connected to the communications busses?

any other drivability symtoms present when the fault occurs?

The IPC will turn on the traction warning lamp if it stops hearing from the EBCM. The EBCM is giving a clue with the loss of comm code. Being as this is a fleet vehicle there maybe something added for data recording or fuel/speed limiting gone awry that is interrupting state of health messages between modules. EMI from another failing electrical component such as alternator or other add on acessories are possible culprits 

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Andrew from Midland

 

Technician
 

I have a factory scan tool on the way tomorrow to check on what module or modules come offline when. The light comes on. All three trucks are fleet trucks . I removed the GPS fuses off one to make sure and problem still persist . The GPS was tied into the fuse box in engine bay and not connected to the dlc . But since pulling a fuse is easy tried it anyway and no dice on the GPS being the culprit. The only symptoms I can say is happening is shifting becomes delayed when fault happens on acceleration. But I can also make the fault happen in park feathering the pedal around 1,200 to 2,000 rpm. Not always but I can eventually get it to trigger like that. And more success recreating while in motion under acceleration. 

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Nicholas from Brooklyn

 

Diagnostician
 

Not sure if this applies, there is a TSB about non oem tires causing traction light to blink under acceleration.

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