I'm getting intermittent ESC, Traction and ABS lights/warnings. They started a day after I finished replacing my rear brakes. I haven't unplugged the wires going to the rear hubs (I think they go to the hubs). I did replace rear pads, rotors and calipers. I also bled and flushed the brake fluid at each wheel, per the service procedure. I skipped the master cylinder, booster, etc flush part, though. Seems odd that this would happen right after my brake job, and not be related. Every time I get this car working correctly, something else breaks on it...

The brake fluid that was there when I started was bad. It was a combo of black and milky white. Strange, since I recently had a shop replace the front calipers, which I thought would require bleeding the new calipers. Found air in the fronts when I bled them.

 

Thats why you do your own work lol.

You need a Tech 2 to scan the ABS system. It will tell you which wheel speed sensor is bad. In my experience, my rear left (DS) would always go; I changed it twice in 3 years.

It has nothing to do with the fluid

 

Is there an app for Automatic that will let me go through the log, like a tech 2? It gives me the current codes, but not historic ones.

 

No.
It is not a MIL code; it is an ABS systems control code.

 

This might seem random, but have you had you EPS motor replaced under the recall?

 

I have not. Should I ask about that with the ignition recall? Could that explain the sometimes odd behavior of the steering of this car?

While you're answering questions, have you ever run across a lot of drivetrain slack when in gear. This car has more drivetrain slack than a motorcycle with a dangerously loose chain. Would that be bad half shafts or a bad clutch maybe? Something in the transmission? We have another cobalt that seems to have a very tight drivetrain. I think that one had a much better first owner, as nothing ever seems to go wrong with it. This one throws a new code every time I fix the last one.

 

I have my original eps and its going out. I will get random codes for abs and a few other things because of it.

Are you sure its the drivetrain that has slack or do you mean the shift linkage? There are quite a few plastic pieces in the linkage that could wear out and cause excessive play.

 

The slack in the drivetrain doesn't appear to have anything to do with shifting, or a particular gear. When switching between the engine driving the wheels (accelerating) and the wheels driving the engine (engine braking/decelerating/coasting), or vice versa, without any change in gear or use of the clutch, there's noticeable slack and then a catch in the moment that the slack is taken up by the drivetrain. The car also shakes somewhat unusually when reversing. I guess it could also be a bad engine mount...

For the closest comparison I can think of, take a motorcycle, dirtbike, atv or bmx bicycle and put a really loose chain on it. Then try accelerating and decelerating a few times without changing gears. You'll notice the effect of the slack of the chain as you switch back and forth between accel and decel.

The codes started right after I replaced rear calipers, rotors, pads and brake fluid. It happened maybe 3 or 4 times over the course of the 3 days following the brake work. Maybe I dripped some brake fluid onto one of the sensor lines and ate a hole in part of it?

Any reason the brakes on my fiancee's cobalt ls would feel like they bite harder than the ones on my sstc? Her car's pedal has always felt more solid too. I bled all 6 of the caliper ports, and flushed 2L of TYP 200 through the braking system when I bled it. The ABS doesn't seem to kick in very easily on the sstc either. Just some gripes about things I noticed. Her brakes seem to inspire more confidence, engage more easily, and bite harder.

 

OK, I get what you mean about the drivetrain. My only guess is that its because of the tranny and or differential. Yours is obviously different and made for sportier driving so its going to allow a certain amount of slip on deceleration.

As far as I know brake fluid has anti corrosives in it so it shouldn't have affected your sensors unless you just drenched them with it.

Did you use oe brake parts or aftermarket?

 

wheel speed sensor is bad, when u find which one and change it, put silicon on the back of the connection on the harness where the wires goes into the plug as well, mine kept screwing up in the rain till I did that.

 

I used all oe brake parts. It's possible the shop that did the front didn't use oe rotors or pads, and just whacked me for a lot of money. They didn't bleed the brakes when changing calipers, after all. I'm guessing they would have used oe calipers, as they still have brembo covers on them. I don't think it would be worth it to them to not replace the calipers. They'd look different if they only replaced one, and reconditioning the one would cost more in time than buying two.

I haven't seen the esc/traction/abs issue again. Someone suggested it might be dust on a sensor from the brake job that washed off with the first rain. Didn't think I made a lot of dust, but haven't seen it again.