[SVKcars]

Can anyone tell me what's wrong with my car?

I have an issue where my Stabilitrak, ABS, Electronic Parking, and Brake light turn on while I am driving, along with the display showing "Service Rear Axle" and "Rear Axle System off."

While all of this is happening, my power steering assist turns off and shows no message for it, so it's like driving a brick. I have also noticed that my parking assist and GPS turn off as well as G force, and eLSD display no data.

There is no check engine light and the problem only happens 45 seconds at a time. I have noticed that the problem triggers when I come to a complete stop or making a left turn (only sometimes). There are times where the car is completely fine, and times where the problem happens every 5-10 mins.

The Chevy dealership had my vehicle for almost a month and came to the conclusion that my Body Control Module needed to replaced, and so they did that and said it was all good.... until the day I picked it up, the problem was still happening.

The only mods I have are Texas Speed Long Tube Headers, Rotofab Big Gulp Intake, Flex Fuel Sensor, and a street tune from DBR High Performance, which shouldn't be causing the issue. The setup is perfect, except for 1 bolt on my steering rack hitting my headers when making a right turn. I'm not sure if this could be causing a problem with the power steering, making the BCM go haywire (has been hitting my headers for 3 months and have not had a chance to fix it yet).

Anybody have an idea of what it could be?

2020 ZL1 1LE / 6400 Miles

Codes:
U077
U0121
U0126
U0132
U0136
U0139
U0140
U0151
U0422
U042B
U1814
U1833
U2099

[cam765]

Just adding some description below in case anyone is wondering what codes these are. For many of these "U" codes that say "Lost Communication with...", the service procedure for diagnosing a fault from these codes stops when you have certain codes also present including U0077, U1814, U2099. So I would say these are the ones to look at first.

U0077 - Control Module Communication Chassis Expansion CAN Bus Off
U0121 - Lost Communication with Electronic Brake Control Module
U0126 - Lost Communication With Steering Wheel Angle Sensor Module
U0132 - Lost Communication With Suspension Control Module
U0136 - Lost Communication With Differential Control Module - Rear
U0139 - Lost Communication With Suspension Control Module 2
U0140 - Lost Communication With Body Control Module
U0151 - Lost Communication With Inflatable Restraint Sensing and Diagnostic Module
U0422 - Invalid Data Received From Body Control Module
U042B - Invalid Data Received From Chassis Control Module
U1814 - Powertrain Wake-Up Communication Circuit
U1833 - Lost Communication with Electronic Brake Control Module on Chassis Expansion CAN Bus
U2099 - High Speed Communication Enable Circuit

[Valsec0]

I have the same issue in my car, dtc codes in DTC_1 attached image.
U0415
U1833
U0077
U0126
U0428


I also have some problems with power steering wheel, see STEERING_1 attached image. And some weird moves on batterie voltage, I don´t now if this is normal, see BATT_1.


I always have the display showing "Service Rear Axle", "Stability track", "Park assist off" and "Service Power Steering, drive with care".



I am waiting steering wheel angle sensor to be replaced.


Only once I have turned on without any issue, before reprogramming BCM. I think the problem could be there, but lot of people said everything goes wrong again before a new one...


I have checked fuse boxes completely. I´m going to try disconnect the batterie more than once (only once doesn´t work) and upgrade ground connections.


Please any help

[cam765]

As I'm sure you know already, U0126 and U0428 are for loss of communication with steering wheel angle sensor module and invalid data received from SWA sensor module. I would check connections for any that or loose or maybe bent/damaged pins inside the connector. There is a relearn procedure for this, if you do end up installing a new one.

U0077 is a very testable. There is a procedure for testing the Serial Data Circuits for a Short to Voltage, Short to Ground, Open/High Resistance, and the Device Circuits. Following this procedure would narrow down the issue, although it is very tedious and requires you to gain access to suspect modules, which could require some disassembly.

So I would recommend figuring out what is going on with your steering wheel angle sensor first. It may even clear U0077 once you get that resolved.

[SVKcars]

I just recently found that the wiring harness running to my BCM was touching my headers and a hole was burned through the outer layer but not into the wires. I’ve done some testing with heat wrap and it seems to have stopped a lot of the lights from coming on except my abs and loss of power steering assist. Chevy will be putting in a new harness tomorrow and we will see if that works!

Don’t know why Chevy couldn’t figure that out themselves after having the car for 30+ days...

[Rock-It Man]

Originally Posted by SVKcars

I just recently found that the wiring harness running to my BCM was touching my headers and a hole was burned through the outer layer but not into the wires. I’ve done some testing with heat wrap and it seems to have stopped a lot of the lights from coming on except my abs and loss of power steering assist. Chevy will be putting in a new harness tomorrow and we will see if that works!

Don’t know why Chevy couldn’t figure that out themselves after having the car for 30+ days...

I just read this thread and damn, as soon as I learned you had headers, I was betting on the melted insulation diagnosis.

Headers and today's cars don't go together for this reason.

[ember1205]

Going out on a bit of a limb, especially with some of my reasoning, you likely have a grounding problem.

In my 2015 Silverado, I was getting an intermittent notice that there was an issue with the integrated trailer brake. It's an issue that does have a couple of known resolutions that include replacing a relay behind the dash or the controller under the bed. In -my- case, it was caused by the deteriorated / failed weather seal on the third brake light. Water was getting into that light housing and causing a short situation. Once I emptied that housing and replaced the weather seal, the problem went away permanently.

[funked1]

I had that kind of stuff happen when I was using a OBDLink Bluetooth MX reader. Chucked that thing right in the trash can.

[arpad_m]

Originally Posted by SVKcars

I just recently found that the wiring harness running to my BCM was touching my headers and a hole was burned through the outer layer but not into the wires. I’ve done some testing with heat wrap and it seems to have stopped a lot of the lights from coming on except my abs and loss of power steering assist. Chevy will be putting in a new harness tomorrow and we will see if that works!

Don’t know why Chevy couldn’t figure that out themselves after having the car for 30+ days...

Point them to this forum Plenty of posts about wiring harnesses and plug wires getting too close to headers, and adding heat wrap and/or rerouting the harness to avoid the issue.

To be fair, though, you have aftermarket headers, and I doubt they spent hours every one of those 30+ days researching custom components.

[ember1205]

Originally Posted by arpad_m

Point them to this forum Plenty of posts about wiring harnesses and plug wires getting too close to headers, and adding heat wrap and/or rerouting the harness to avoid the issue.

To be fair, though, you have aftermarket headers, and I doubt they spent hours every one of those 30+ days researching custom components.

Melted wires are common enough that it shouldn't matter if the headers aren't stock. How long does it take to check the wires in that area? Hell... it would mean that they could come back and say "found your problem, but it isn't covered under warranty", allowing them to CHARGE for the repair...

[Puddin]

Originally Posted by SVKcars

Can anyone tell me what's wrong with my car?

I have an issue where my Stabilitrak, ABS, Electronic Parking, and Brake light turn on while I am driving, along with the display showing "Service Rear Axle" and "Rear Axle System off."

While all of this is happening, my power steering assist turns off and shows no message for it, so it's like driving a brick. I have also noticed that my parking assist and GPS turn off as well as G force, and eLSD display no data.

There is no check engine light and the problem only happens 45 seconds at a time. I have noticed that the problem triggers when I come to a complete stop or making a left turn (only sometimes). There are times where the car is completely fine, and times where the problem happens every 5-10 mins.

The Chevy dealership had my vehicle for almost a month and came to the conclusion that my Body Control Module needed to replaced, and so they did that and said it was all good.... until the day I picked it up, the problem was still happening.

The only mods I have are Texas Speed Long Tube Headers, Rotofab Big Gulp Intake, Flex Fuel Sensor, and a street tune from DBR High Performance, which shouldn't be causing the issue. The setup is perfect, except for 1 bolt on my steering rack hitting my headers when making a right turn. I'm not sure if this could be causing a problem with the power steering, making the BCM go haywire (has been hitting my headers for 3 months and have not had a chance to fix it yet).

Anybody have an idea of what it could be?

2020 ZL1 1LE / 6400 Miles

Codes:
U077
U0121
U0126
U0132
U0136
U0139
U0140
U0151
U0422
U042B
U1814
U1833
U2099

Yep sounds like your headers have burned the harness on the passenger side by your coolant reservoir. If you haven't zip tied that harness away and to the body of the car that's most likely your problem.

[Valsec0]

I have verified canbus line and the problem is between ABS control module (last one) and power steering control module.



How can I fix the harness? Maybe the best idea is replace complete harness, I can´t find part number.

[Skyman2112]

Same thing happened to mine after adding headers. The harness needs an extra tie right under the overflow tank to prevent the harness from bulging into the header pipe

Originally Posted by SVKcars

I just recently found that the wiring harness running to my BCM was touching my headers and a hole was burned through the outer layer but not into the wires. I’ve done some testing with heat wrap and it seems to have stopped a lot of the lights from coming on except my abs and loss of power steering assist. Chevy will be putting in a new harness tomorrow and we will see if that works!

Don’t know why Chevy couldn’t figure that out themselves after having the car for 30+ days...

[Timbo-1LE]

I believe I have the same issue. Fresh headers and cam, codes U 121,126,132,136,139,140,151,422,1814,1837,2099. Wiring harness is pretty close to the headers passenger side, stabiltrack warning, service axle, service parking brake, parking brake light and/or parking brake actually activated. Once it cools down will check for burns and at least move it. Drove it 1100 miles home, happened once and reset it by power off all good rest of the trip... took it out tonight, got on it once a little, turned left and went nuts for next five minutes...

Question, if burnt, if minor, can it be repaired or is it typically a harness replacement? I get without visuals hard to guess, just checking to see if anyone has had one repaired as I need the car ready by Thursday...

Thx