ABS/traction control failure help
 

Hey guys-

Hoping someone has had a similar experience or maybe help shed some light on a problem-


When I had the car out for the last track day, I experienced a rather unusual sensation driving to/from the track-

The car felt like it was tram-lining REALLY bad, like it had 305 series tires and a flat alignment (and it doesn't). The back end was walking all over the place. I mean it would drive straight, then I'd feel the back end "dance" around like I was going over uneven pavement, then it would stop. Then do it again. All while I was driving straight, or through gentle curves.

On the track --where I run pedal dance mode-- the car felt rock solid and stable. Driving that same the stretch of highway/road in 'pedal dance' mode to get gas - it maybe felt a bit better, but still the type of same swaying behaviour.

Fast forward to the last track session of the day, and after several laps the left front wheel locked up REAL bad. Completely caught me off guard, flat spotting and ruining the relatively new AR-1.

I cruised back to the pits and noticed the "stability control" (?) idiot light in the center of the dash was now lit up (ie not the one to the right that lights up with pedal dance - it was already lit) and the ABS light was on too.

Let the car sit for a while as I packed up, and when I restarted it, ABS and trac light were off, but it exhibited the same 'swaying' feel as I drove home. Took it for a bit of a cruise after unloading, and maybe 10 miles later those 2 lights lit up again.

At that time I pulled over and felt the rear wheels and they were warm to the touch, even though I hadn't been braking hard, which makes me think this is somehow tied in to the stability control system.

If it is - what I don't get is why I still experienced this in pedal dance mode on the road/highway but NOTHING on track?


Any ideas what I should be looking for? The car is parked a few hours away from me and I'd like to have a plan of attack to check it over when I go back.


My initial thought was a wheel speed sensor, but I don't get how that would affect things in pedal dance mode?

Next thought was the clock spring, but then I remembered that after having issues with it a few years back (when I went to an aftermarket steering wheel) going into pedal dance mode stopped those problems cold.

The reason the clock spring occurred to me, is that I noticed my steering wheel was "off center" while driving straight - and I'm pretty sure it left the alignment shop last year with it "centered".


I tried to pull codes off of it when the ABS light and center-dash traction control idiot light were both on, but got no codes using the OBDlinkLX :(

A couple of things come to mind. First one, inspect wheel bearings (raise car, try to move wheels side to side and up/down). Check for looseness anywhere there. After that, check your wheel speed sensors, see if any of them are damaged. I've had one wheelspeed sensor damaged and it did what you say your car is doing. Also, after switching the sensor with a good one, the car had a ABS related CEL and it would not go away, Torque doesnt seem to be able to erase those codes, had to take it to a mecanic so he could erase it with his reader, never came back.

UPDATE:

So - had the car on the quickjack.

Rear wheels BOTH had lots of play. Thought bearings but they were too quiet for that - and on further examination it was clear the wheels were pivoting directionally - so I pulled them and checked the arms-

And I found that BOTH rear toe arms were loose at the outside joint! Allowing a significant amount of movement and therefore toe change!


When tightened down, the castle nuts are too far past the drilled holes for the cotter pins to lock them in place. I'm thinking hardened washers might help space things out so both top (flat) and bottom (camfered) castle nuts can be locked in place. Or if that doesn't work using a jamb nut-


Need to pick up parts and head back.

Not sure if this is what tripped the error codes or not?!? Changing toe certainly seems like something that could mess up the stability control system - but why the ABS light?

And now thinking further, I'm wondering if the excess toe movement that was happening damaged an ABS sensor ?

You didn't mention that the ABS sensor was actually damaged.

Either way, I'm fairly certain that the ABS is tied to the traction control system and it is common to get a matching ABS light when your alignment is way off.

Wheel speed sensors are critical in how the car works without the pedal dance on.

I definitely noticed the car behaving differently between pedal dance on/off.

The way the back end swayed around was definitely less pronounced in pedal dance mode, which makes sense.


However - I WAS running in pedal dance mode when the ABS failed/light came on and the "TC active" light in the center of the dash went full solid.

I didn't check that when I worked on the car yesterday but will definitely do so once I go back in.

I imagine there is also some kind of 'ring' the ABS sensor reads off of so I will also check all those for damage/dirt/issues.

The wheel speed sensor goes into a slot that reads "teeth". Make sure it's all clean in there on all 4 corners.

Now that you have worked in the suspension an alignment would be a good idea.

MY guess is that its not damaged. I had a very similar issue to yours and when there was no damage to the sensor. You might need a professional level tool to reset ABS codes, Torque and similar phone apps with an OBD2 connector wont clear ABS codes (at least not in my car, I dont think this is specific to my car :) ).

Post said no codes, just the dash light. And in my experience, that will clear up on its own after a few miles once the car is aligned. Or if you have it done at a shop, they can likely take care of it for you.

ABS "codes" are different. You could have your ABS light on and read nothing on a OBD2 reader. If it cant read codes from the ABS system, its possible to not see anything. Its possible that it goes on its own, but in my case, my car is not registered anymore, I cant daily drive it and wait X miles to see if it clears up.

Always something to think about!


However in my case, so far only the attachment hardware has been removed from the end of the toe links, so there will be no change to alignment settings as the hardware uses self centering conical seats where it connects to the rod end at the end of the toe link :)

Thank you for the tip!


I presume I need to remove the sensors to clean out in there. Are we thinking compressed air or will brake parts cleaner do the trick ?

air should be fine

I once had a wheel speed sensor going bad and it would randomly put me into limp mode. Was that happening to you when you lights came on? If I recall I couldn't go over about 4000 rpm.

Either way, I've had a rear sensor go bad for no apparent reason. Consider logging some wheel speed data and see if any of them are doing anything wacky. I my case, one sensor would give a couple intermittent readings that were way lower than the other 3 and causing the lights to come on. The issue became more repeatable as my speed increased.

I'm not sure - as soon as the dash lit up I putted back to the pits and parked it.


Thanks for the wheel speed tip! :)