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Old 06-29-2020, 09:40 PM   #1
ForgotUsername
 
Drives: 2010 Camaro RS LT2
Join Date: May 2018
Location: Detroit
Posts: 17
solved: STABILITRAK, ABS pump freakout, C0035

I had a condition where my ABS pump was stuttering and all my braking assist lights would illuminate on every drive, and the source problem surprised me.

TL;DR the hubs needed replaced.

(if image is missing here, check attachments)

Symptoms:
I would drive at low speeds (0-39mph) and hear the ABS pump clicking with every rotation of the wheel, and when I go over 40mph then the clicking would stop and ABS/traction control/stability control would all light up on the dash and DIC would read SERVICE STABILITRAK. All the braking aids would basically just give up and turn off, aka if I slammed the brakes then all wheels would lock up. And if I did normal braking, then the pump would freak out and behave as if the car is sliding on ice. Neat!

Side note: If your car shows SERVICE STABILITRAK only at startup and it goes away, then it is not this same issue. For that issue, see this thread, post four. GM addressed this and they basically say to ignore it.

Background:
-I had just changed my front calipers for an unrelated problem
-I initially thought this was just air in the ABS pump after I changed the calipers. But after re-bleeding (I did several pressure bleeds, including using the GDS2 dealer service tool's ABS pump autobleed function) the problem still existed unchanged.

Diagnosis:
My generic OBD2 reader couldn't read these codes, so I used a VCX Nano and GDS2 to pull these codes. I should make a post on this tool, it doesn't seem like many people use it.

The error codes I saw were as follows:
Electronic Brake Control Module
DTC: C0035
Symptom byte: 5A
Description: Left Front Wheel Speed Sensor Circuit
Symptom description: Not Plausible
(if image is missing here, check attachments)

Note that you might get a similar code which corresponds with your wheel:
C0035 (front left), C0040 (front right)
C0045 (rear left), C0050 (rear right)

There is actually a TSB for exactly these symptoms, Bulletin No.: 17-NA-047. It basically says that your wheel speed sensor ring is dirty and needs to be cleaned. This applies to ALL 5th gen camaros as well as many other GM cars. Here's that bulletin:

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I confirmed that there's a wheel speed issue by charting the sensor data for left versus right. See how the right side is nice and smooth, whereas the left side has obvious jumps in the data?

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-I removed the wheel speed sensor, inserted a toothbrush + brake cleaner into the hole, and rotated the wheel hub to clean the wheel hub's magnetic sensor ring. No change to the problem.
-I then swapped the wheel speed sensors from left to right, since they are both the same part number. No change to the problem. It's not the sensor.

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I removed the cover behind the wheel hub so that I could clearly see the ABS ring. I did this by hammering a socket extension through the hole in the hub. A-ha! The issue was suddenly obvious.

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The ABS ring was damaged and so brittle that it was falling apart. See the section that's missing and cracked off? This accounts for the gaps of data on the wheel speed charts. Time for new hubs. This is a great video for changing your hubs. Here's what the new hubs looked like versus the existing ones:

(if image is missing here, check attachments)


After changing the front hubs, the issue was gone!

No more lights or freaking out from the ABS pump. I think that the fact that this happened at the same time I was changing my calipers was a coincidence. I guess because I was working in that area, it's plausible that while wrestling the caliper into place I was able to bump the hub and damage its brittle ABS ring.

Oh, and my car is a 2010 Camaro LT2 RS (v6) with 141,000 miles at the time.

I hope this saves someone from the headache that I went through!
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Last edited by ForgotUsername; 10-15-2021 at 01:08 AM. Reason: Images went missing for some reason.
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