Wont start "Chassis control module"

Bmcghan09 · February 25, 2020

I just bought a 2014 Sierra 1500 Z71 double cab with 95.000 miles. Saturday I went to get my hair cut and after got in my truck to leave. It wouldn't start. I keep a scan tool on me so I scanned it and no codes. Everything would turn on and work just no signal to the starter. I call onstar for towing and I'm sitting there randomly trying to start it. Putting it in neutral, cycling the locks all the old tricks. I open the hood, check the cables and everything is fine. Go to start it and boom started right up. I drive right to the only dealer who's open and they determined it was the license plate LED lights and they should be normal lights. Dealer tells me that's all and sends me on my way. I go to start it to leave and once again it wont start. They scan it again and determine the chassis control module was not communicating for some unknown reason. I leave it there and all day yesterday and today its been starting just fine. So I guess I am going to pick it up tonight. I don't like the idea of rolling the dice every time I go to start my truck.

Anyone experience this or have an idea? Dealer is clueless.

Bash74 · February 25, 2020

So what did the dealer say it wasnt communicating too. For instance, I had a no communication fault (U1556) but it was for the trailer brake module not communicating. This didnt stop the truck from being able to be driven. So I am curious what communication fault they found.

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BlaineBug · February 26, 2020

Why would the LED lights matter?

I too am having electrical issues with a 2019 Yukon. At the dealership twice now. "Rolling the dice" as you say. If there aren't any codes stored they don't investigate or diagnose, they just send you back on your way until it happens again.

Edited February 26, 2020 by BlaineBug

Bmcghan09 · February 26, 2020

Well, at first it was "license plate bracket" and circuit had feed back and was interrupting the BCM/CCM. So I pulled the LED lights at their recommendation, I did not have the code for that. For those asking about LED lights, this model and up the electrical system measures the resistance of ALL the circuits. When not equipped with factory LED and you switch over it can cause "feedback" or resistance issues. I've heard of this before but with the quality of GM and all the electrical issues the LED lights carry no resistance compared to your normal bulb, therefore there can be power to other grounds in the system.

But back to my truck, after the initial license plate bracket feed back issue I pulled the bulbs and it wouldn't start. Then we got a ccm communication issue, not communicating at all (I don't have the code for that). The following day the truck was starting great but pulled a HVAC communication code U0140, the controls worked fine. Today the truck is working fine. I personally think there's a ground issue or something shorting and feeding power to the grounds of the truck. I live here in Lansing MI where there is a ton of GM plants and suppliers. If I told you the personal first hand stories I have heard about quality control issues you guys would freak.

I've had newer Fords for the last 8 years and never had any of these issues. I loved the look of the GM and was trying to save a little money as I just bought a house. The fords are priced higher so I gambled with the GM. If this does it again and the dealer cannot figure it out, I am going to go attempt to "tune and delete" what I can so the drive-ability is basically standalone relying on the ECM only. I love the look of the truck and it seemed finally GM stepped up their build quality but it appears to be the appearance only.

My background, I used to be a certified technician (Not GM factory trained). I've tuned and ran stand-alone ECM's for older 1st-2nd gen 5.3s.

silveradosid · February 26, 2020

there was a post about led lights, i think it was called my 457 dollar mistake. apparently these truck do a diagnostic check on lights when you shut it down. the led lights dont return hte correct answer to the check causing the module not to go to sleep and it drains the battery

BlaineBug · February 26, 2020

1 hour ago, Bmcghan09 said:

Well, at first it was "license plate bracket" and circuit had feed back and was interrupting the BCM/CCM. So I pulled the LED lights at their recommendation, I did not have the code for that. For those asking about LED lights, this model and up the electrical system measures the resistance of ALL the circuits. When not equipped with factory LED and you switch over it can cause "feedback" or resistance issues. I've heard of this before but with the quality of GM and all the electrical issues the LED lights carry no resistance compared to your normal bulb, therefore there can be power to other grounds in the system.

But back to my truck, after the initial license plate bracket feed back issue I pulled the bulbs and it wouldn't start. Then we got a ccm communication issue, not communicating at all (I don't have the code for that). The following day the truck was starting great but pulled a HVAC communication code U0140, the controls worked fine. Today the truck is working fine. I personally think there's a ground issue or something shorting and feeding power to the grounds of the truck. I live here in Lansing MI where there is a ton of GM plants and suppliers. If I told you the personal first hand stories I have heard about quality control issues you guys would freak.

I've had newer Fords for the last 8 years and never had any of these issues. I loved the look of the GM and was trying to save a little money as I just bought a house. The fords are priced higher so I gambled with the GM. If this does it again and the dealer cannot figure it out, I am going to go attempt to "tune and delete" what I can so the drive-ability is basically standalone relying on the ECM only. I love the look of the truck and it seemed finally GM stepped up their build quality but it appears to be the appearance only.

My background, I used to be a certified technician (Not GM factory trained). I've tuned and ran stand-alone ECM's for older 1st-2nd gen 5.3s.

Very strange. How were the LED bulbs at fault if your truck had issues again when leaving the dealership the first time? I'll be PMing you shortly.

Edited February 26, 2020 by BlaineBug

Bash74 · February 26, 2020

Well, at first it was "license plate bracket" and circuit had feed back and was interrupting the BCM/CCM. So I pulled the LED lights at their recommendation, I did not have the code for that. For those asking about LED lights, this model and up the electrical system measures the resistance of ALL the circuits. When not equipped with factory LED and you switch over it can cause "feedback" or resistance issues. I've heard of this before but with the quality of GM and all the electrical issues the LED lights carry no resistance compared to your normal bulb, therefore there can be power to other grounds in the system.

But back to my truck, after the initial license plate bracket feed back issue I pulled the bulbs and it wouldn't start. Then we got a ccm communication issue, not communicating at all (I don't have the code for that). The following day the truck was starting great but pulled a HVAC communication code U0140, the controls worked fine. Today the truck is working fine. I personally think there's a ground issue or something shorting and feeding power to the grounds of the truck. I live here in Lansing MI where there is a ton of GM plants and suppliers. If I told you the personal first hand stories I have heard about quality control issues you guys would freak.
I've had newer Fords for the last 8 years and never had any of these issues. I loved the look of the GM and was trying to save a little money as I just bought a house. The fords are priced higher so I gambled with the GM. If this does it again and the dealer cannot figure it out, I am going to go attempt to "tune and delete" what I can so the drive-ability is basically standalone relying on the ECM only. I love the look of the truck and it seemed finally GM stepped up their build quality but it appears to be the appearance only.

My background, I used to be a certified technician (Not GM factory trained). I've tuned and ran stand-alone ECM's for older 1st-2nd gen 5.3s.

If you pulled a U0140 that is a communication fault with the BCM a U0164 would be HVAC. The U0140 can stop a vehicle from starting especially because of the anti theft. I would scan truck everyday for a few days. If you keep getting U0140 then you might be having a BCM problem.

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Bmcghan09 · February 26, 2020

28 minutes ago, Bash74 said:

If you pulled a U0140 that is a communication fault with the BCM a U0164 would be HVAC. The U0140 can stop a vehicle from starting especially because of the anti theft. I would scan truck everyday for a few days. If you keep getting U0140 then you might be having a BCM problem.

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The paper from the dealer said U0140 loss hvac loss to BCM but, noted for future reference. I'll have to see if my buddy can scan it with his scan tool. Mine only pulls engine, ABS and SRS

BlaineBug · February 26, 2020

U codes are history codes aren't they? One of the service advisers where my Yukon sits on Friday said "those really aren't codes" or something along the lines of them not being codes worth paying attention to?

I remember when it went in for the first time it had three history codes (U0100, U0121, & U0422) and once again they said history codes didn't mean much because they could have happened anytime and who knows when and didn't help them diagnose it at all.

Edited February 26, 2020 by BlaineBug

Bmcghan09 · February 26, 2020

1 minute ago, BlaineBug said:

U codes are history codes aren't they? One of the service advisers where my Yukon sits on Friday said "those really aren't codes" or something along the lines of them not being codes worth paying attention to?

I remember when it went in the first time it had three "history" codes and once again they said history codes didn't mean much because they could have happened anytime and who knows when.

Anything U coded is Electrical. They are most defiantly real, and they are a real pain in the ass.

BlaineBug · February 26, 2020

Genius service advisers then. How lovely. I feel as if a lot of these people in automotive tech customer service don't have the first clue about automotive tech. You can just tell through conversations when they go silent it's a defense mechanism rather than just telling you "You may as well be speaking gibberish, sir."

Is it possible to acquire a fresh U code without a check engine light coming on? Because that is one thing that hasn't turned on to alert of a fault, even when my vehicle's failures have been active!

Edited February 26, 2020 by BlaineBug

Timmer66 · February 26, 2020

This may or may not be related as there are so many ways a system can fail but the comment about a failure to communicate with the chassis control module is/was part of my issue. I've had a serious problem lately with my 2016 Silverado dying on me but it usually throws up a bunch errors starting with Service Trailer Brake and Stabilitrac Off, before going into limp along mode and then eventually just packing it in, though the engine continues to run but the tack drops to zero. Once I shut it off it will not re-start however at one point when it wouldn't start I disconnected the EBCM (ABS) and it started. I reconnected it and it wouldn't start (suggesting the issue was the EBCM or the CCM or the wiring in between). There is also a clear correlation between this happening and wet sloppy Ontario roads. Twice I've had it towed to a dealer and what they've found is a slew of communication errors between all of the devices on the main GMLAN which includes the ECM, TCM, TCCM, Telematics module, HMI module, Body Control Module, PSCM, EBCM and finally the Chassis Control Module. Unfortunately however by the time they've taken it into the shop, it runs and there are no active faults. Two dealers spent a combined 14 hours pulling apart wiring harnesses starting where they go through the door sill all the way to the chassis control module and found nothing. They said it's almost always a small nick in the wire with signs of corrosion around it. Eventually I got tired of paying big bucks for someone to unwrap wires so I took it home and started pulling it apart myself and checking the wires inch by inch very carefully. Eventually in a section just in front of the left rear wheel I found what is almost certainly the culprit, exactly as described. The nick was in an area that neither dealer had touched I suspect because it's such a pain to get at. In my case the wire wrapping had loosened up and the wrappings had filled with mud and salty water but I suspect subsequently drained out upon sitting allowing the communications to resume. Appreciate that the network operates between 1 and 3 volts so pulling it down doesn't take much. As of this morning I have it all back together and no fault codes. Fingers crossed that I've fixed it. It's just started snowing so tomorrow will be a good day for a test drive.

Edited February 26, 2020 by Timmer66
Picture too big

Bmcghan09 · February 26, 2020

4 minutes ago, Timmer66 said:

This may or may not be related as there are so many ways a system can fail but the comment about a failure to communicate with the chassis control module is/was part of my issue. I've had a serious problem lately with my 2016 Silverado dying on me but it usually throws up a bunch errors starting with Service Trailer Brake and Stabilitrac Off, before going into limp along mode and then eventually just packing it in, though the engine continues to run but the tack drops to zero. Once I shut it off it will not re-start however at one point when it wouldn't start I disconnected the EBCM (ABS) and it started. I reconnected it and it wouldn't start (suggesting the issue was the EBCM or the CCM or the wiring in between). There is also a clear correlation between this happening and wet sloppy Ontario roads. Twice I've had it towed to a dealer and what they've found is a slew of communication errors between all of the devices on the main GMLAN which includes the ECM, TCM, TCCM, Telematics module, HMI module, Body Control Module, PSCM, EBCM and finally the Chassis Control Module. Unfortunately however by the time they've taken it into the shop, it runs and there are no active faults. Two dealers spent a combined 14 hours pulling apart wiring harnesses starting where they go through the door sill all the way to the chassis control module and found nothing. They said it's almost always a small nick in the wire with signs of corrosion around it. Eventually I got tired of paying big bucks for someone to unwrap wires so I took it home and started pulling it apart myself and checking the wires inch by inch very carefully. Eventually in a section just in front of the left rear wheel I found what is almost certainly the culprit, exactly as described. The nick was in an area that neither dealer had touched I suspect because it's such a pain to get at. In my case the wire wrapping had loosened up and the wrappings had filled with mud and salty water but I suspect subsequently drained out upon sitting allowing the communications to resume. Appreciate that the network operates between 1 and 3 volts so pulling it down doesn't take much. As of this morning I have it all back together and no fault codes. Fingers crossed that I've fixed it. It's just started snowing so tomorrow will be a good day for a test drive.

This is super interesting. If I start pulling more codes I may touch base with you and dig further.

tbarn · February 26, 2020

1 hour ago, BlaineBug said:

Genius service advisers then. How lovely. I feel as if a lot of these people in automotive tech customer service don't have the first clue about automotive tech. You can just tell through conversations when they go silent it's a defense mechanism rather than just telling you "You may as well be speaking gibberish, sir."

Is it possible to acquire a fresh U code without a check engine light coming on? Because that is one thing that hasn't turned on to alert of a fault, even when my vehicle's failures have been active!

HELLOOO!!!!!! Why is so hard for everyone to believe that the vast majority of service writers are idiots. They are!

There are lots of U codes that will not set an ECM code turning on the SES light.

BlaineBug · February 26, 2020

It's not hard to believe. But then again there are other "entry level" positions out there that require so much experience and knowledge.....you'd think having a basic understanding of automotive tech would be a prerequisite to dealing at any position within the service department.

@tbarn I will be private messaging you as well. Your information about tachometer reading nothing while engine running intrigues me.

Edited February 26, 2020 by BlaineBug