2000 S70 Traction Control Engaging Randomly

[bmdubya1198]

I have one last issue that I'm trying to diagnose with my 2000 S70 GLT before selling, and of course it's with the ABS/STC.
I've only had it happen twice, but while accelerating, STC will engage and the light will flash, killing power. If I let off and wait, it'll stop. My solution the first time was to just turn off STC, which will work obviously but I want this issue fixed so STC works properly.

I checked the wheel speed sensor readings on VIDA while driving, and none of them show any discrepancies worth noting. I cleaned off all the sensors, but after having it happen again today, that didn't help.

I'll double check the tone rings on the front axles, but I know for sure the axle bolts are torque properly. I'm thinking the ABS module may be dying, but figured I'd ask in case anyone else has had this issue.
No codes in VIDA, although I did have an old code for the left rear WSS. It has yet to return since clearing codes a while before I discovered this problem.

[scot850]

I would be doing the same as you. If you have done the tests on the ABS sensors, then the next thing to check is the tone rings like you have said to ensure none have cracked or have a dirt build up on them.

You also mention you have checked all the torque settings of the axle bolts. Being a 2000, as per abscates notes on another thread they are a consumable part and not to be re-used as they are a stretch to yield. He had issues with this in the past I seem to recall.

The only other thing other than a bad ABS module is possibly a broken internal wire in an ABS sensor. I don't think that it would set an error code, because if it did most cars would have loads of codes being set. So unless you are monitoring this when it happens you may not catch it.

A buddy had an issue with the module which he resolved temporarily by pushing a wedge down between the ABS connector at the module and the wires. This was not a 'proper' fix but just proved there was bad joints in the ABS module. He ran the car like that for 2 years.

Neil.

[bmdubya1198]

I believe I replaced the axle bolts, I’m not sure now that I think about it. I usually do, being that they are TTY.

I’ve seen bad wiring at the module, so I’ll definitely check that out, as well as the sensor wiring.

[scot850]

I wish you luck! I remember the nightmare I had with my old 2000 V70 base. Random lights coming on including the STC/ABS/Engine check lights. Took a while to eventually figure out it was the ABS module. I pulled another from a PnP and fitted it. It was also bad but at least the faults were predictable and consistent. That got me on the phone to Matty for an exchange rebuilt unit and issue went away. I am a stubborn Scot who hates to spend money until I am sure I have exhausted the options and am sure the issue is identified to source.

Neil.

[wizechatmgr]

On my '99, I was having intermittent issues that sounded identical to yours. When I monitored VIDA everything was fine and for the life of me I couldn't find the fault. I too spoke with Matty whom suggested the axle bolts or wheel bearings could be an issue. In my case it turned out to be an axle bolt that wasn't tight to spec. My thought is the ABS microprocessor is quicker than VIDA so it may detect and act long before we'll see symptoms on the screen. I think short of having a shorted sensor, no continuity, or one wildly out of spec, it won't likely complain. Your mileage may vary...

[bmdubya1198]

Interesting... I'll have to get the front wheels off tomorrow and check it out.