taxableabe

2017 Z06 1LZ with 7 Speed manual. Has 27,500 miles now, factory warranty, all stock. I drive this thing everywhere and loved it until this problem.

Been having this gremlin of a problem, service rear axle light appears randomly puts my E-Diff in "---" instead of displaying a number percentage. My stabilitrak also starts interfering a bit too hardcore, any slight sweeper turn and the car wants to brake then let go then brake etc in the corner and it is very scary.

Also right before the light had popped on, my gauges turned off and swept back on and off again and on about 3-4 times in a row then the service rear axle light was on the dashboard.

Dealer has had the car since Tuesday. Actually I took it to another dealer on Monday for Oil, filter and to check out the light, but they said no codes were found. Drove it home that Monday evening and halfway home the light showed up again showing "service rear axle."

So Tuesday I took it to another dealer and luckily the light had come on right before I got to the dealership. Told the dealer not to turn off the car until they can read the code. Unfortunately they told me the first dealer wasn't lying to me and that there are no codes. A few days ago they said they hooked up the machine inside the vehicle to try to get the code to go off while they are driving it and to catch it if that makes sense, still no luck. They still have the car and are wondering how long I feel comfortable doing this. Adviser seems like he is going to bat for me here this time compared to the first dealership, he told me they are in contact now with GM to get some kind of guidance and it isn't looking too good.

I'm starting to think I should have got the C6 ZR1 instead and sucked up the interior looks.

At this point I'd rather they tell me my whole diff was busted and not covered under warranty than them not figuring out what the problem is.

I've done all the searching and googling, and I just feel my problem is a bit odd as no codes are thrown.

555ctsv

Definitely a weird situation. You don't happen to have a Walyens Horizon Dashcan do you?

taxableabe

No, I do not. Definitely something strange. I'm guessing hooking up something like that or a radar can cause some gremlins? Yeah there is nothing of evidence of a radar or dashcam.

Z0HS1CK

Hook up a go-pro or some camera to your steering wheel shroud facing the cluster so you can catch the "service rear axle" the next time it comes up.

Then bring back the car to the dealer with the footage to show them.

If the car is all stock, then yes i would tell them to fix the diff under warranty. You have been to the dealer twice already right? With no solution? I think one more time to the dealer warrants some sort of action.

Stupid question but what about changing the fluid? Was that done?

jlbjr

DJackman

I got a Servixe Rear Axle and a CEL and the engine was misfiring . Took it to the dealer and it was a busted fuel injector cylinder number 5 . 10K miles 2017 MN7

555ctsv

I returned my Waylens camera because Service stabilitrak, Service Rear Diff, and a couple others would flash up and then disappear without a CEL or anything. Turns out the obd2 adapter messes with the can bus system. Removed the camera and no issues since! Was hoping it would be something easy like that for you as well

taxableabe

Yeah I wish it was something easy to figure out. Dealer already knows about the Service Rear Axle light as I drove it in with it showing so they know there is a problem so I don't have to show them proof of it or anything. Hopefully they figure it out in a decent time.

salcolkat

I had the same problem on my 17 1LZ M7 I brought it to the dealership and it was a loose connection at the battery causing the intermittent problem. The computer was going haywire . A while before the problem i hooked up the adaptor for a battery tender to the terminals and somehow one of the connections worked loose. They tightened up the connection and the problem stopped. That was over a year ago. hope this helps.

Bill Dearborn

The problem is that will not help them find the problem. A picture of a message doesn't provide any help. What are they supposed to repair/replace to resolve the issue? If there is no code they have no idea where to look to see what is causing the issue. Service Rear Axle isn't as simple as replacing the rear axle since it could be related to something else and not specifically the rear axle. The rear axle control module interfaces with several other modules in the car and the problem could due to some intermittent that occurs with those other modules. Just like people sometimes see a service code such as service stability control and the problem is located in the engine control module since it has to respond to message from the EBCM and isn't able to respond properly to those messages.

Bill

Z0HS1CK

Bill, not a picture, a video. That's why i said OP should hook up a gopro or some camera (like a cell phone) If OP has PDR maybe he can link to what he was doing (as in driving) in conjunction with the video feed of capturing the cluster illuminating the code and maybe the dealer can work with that. Unless the dealers are blatantly ignoring any possible problem to prevent themselves from fixing anything.

dmaxx3500

they need to ''READ'' live data while driving the car,it takes 2 people,then they need to call ''GM TECH CENTER'',and fix the car

23/C8Z

Voltage issue imo. You mentioned spirited cornering as making this happen also which could be a terminal or ground somewhere.

or even an intermittent dead cell in battery..

maybe they can keep logging until it occurs. Hopefully. What a nightmare. This car scares me thinking of it being out of warranty one day lol.

Bill Dearborn

A video showing the message won't do any more than a picture. It is useless. All a picture or a video proves is the driver saw the message in case they don't believe the driver, however, even if they wholeheartedly believe the driver saw the message it doesn't do them any good without the codes to tell them where to look.

In the case of a Service Rear Axle message the following things could be causing a problem:
High Speed Data Bus
The Rear Diff Clutch Control Module
EBCM
System Voltage which could be either a low voltage, a bad voltage connection or a bad ground.
One of the wheel speed sensors
The EBCM
The ECM
The BCM
The Steering Wheel Angle Sensor
The Inflatable Restraint Sensing and Diagnostic Lateral Acceleration signal
The Inflatable Restraint Sensing and Diagnostic Longitudinal Acceleration signal
The Inflatable Restraint Sensing and Diagnostic Yaw Rate signal
The BCM
The Outside Air Temp Sensor and circuitry including the BCM
The module's rear axle torque feedback signal to the ECM
Rear Diff Clutch Control Temporary Inhibit generated by the module

There are 9 separate DTCs for the rear axle itself. One of those doesn't generate a message, one generates a Rear Axle Disabled Message and the others generate a Service Rear Axle Message. Some of the messages are related to the diff cooler Vs the axle itself. Without codes it is difficult to know where to look no matter how much the Customer is jumping up and down.

The Rear Axle DTCs are all C Codes and more than likely are not readable by a generic OBD II scanner.

Bill

VictorBarron

I know that the battery can play hell with the computer systems in the car.

taxableabe

Dealer called and said the GM Tech and them are changing the Rear Diff Control Module, I believe the one that controls the clutches in the diff electronically. Part should be here Wednesday and they want to get it in and test it out to make sure the light doesn't come on, so hopefully Wednesday evening. Hope this works!

Z0HS1CK

Oh, i did not know this.

Once again, you taught me something. Thanks for the info.

djnice

I had this issue on my 18. It could be the diff control module or many other things as Bill noted. Good to see the dealer is throwing parts at it. Better than doing nothing. See how it goes.

taxableabe

Well, dealer changed that part out and drove it around for a little and Service Rear Axle light came back on. So GM Tech and them are back at square one.

djnice

I was trying to be positive in my previous post, but figured that would happen. The gauges sweeping before this happened makes me think a voltage issue. Unless that was just coincidence, which wouldn't surprise me. I am pretty sure someone posted they had the diff issue due to bad alternator. Alternator tested okay, but when replaced fixed it.

The BCM has to talk to the diff module to enable it and receive a state of health. If you are getting the "---" you should also be getting "rear axle system off" message. Indicating lost communication and the BCM stops enabling the diff.

Did you notice anything else going on or environmental factors (Hot out, rainy, hit a bump, etc) when the diff stops working?