ABS Question

[totech]

My latest problem with my 2 week old car is in the ABS.

It is a 91 - so 4 channel.

When braking some times, dry roads/wet no difference, when the ABS should not be activating, I get the whirr/vibrate of the ABS system activating, then ABS light goes on.

When the car is restarted, it is fine until it does it again.

Brakes are good - pads fine, stops well otherwise.

My thought is if winter ever goes away - to flush out the lines with new fluid.

Anyone experienced this?

And yes I have owned cars with ABS before, and the system seems to work in the snow.

[vrg3]

Are all your tires the same and properly inflated? If the overall diameters are different the ABS system can think it sees skidding when there isn't any.

If that's all okay, you might want to check your ABS sensors. The tone wheels are mounted on the backs of the hubs, and are essentially rings with a bunch of teeth. Check that none of the teeth are damaged or broken. There's also a transducer mounted facing the ring with an electrical wire coming off of it. I don't know how you'd check that, but you could at least make sure it was mounted right and clean.

Beyond that, all I could think of would be to start swapping components, probably starting with the ABS controller. You might want to take it to a dealer; as I understand it, the Select Monitor (Subaru's proprietary diagnostic tool) can talk to the ABS computer.

[IggDawg]

A friend of mine told me something about if wheels are spinning at different speeds when you're not applying brakes (like doing a lot of sliding around and spinning wheels in the snow without using the brakes) the system can try to disable itself. I dunno how much of that is true. My solenoid goes batty about 5 seconds after I turn on my car, then shuts up after whirring for 5 more seconds or so. I figure it's like a POST or something.

[ciper]

check to make sure the "bumped" wheel is tight on the hub. Mine came loose and rubbed on the sensor on another vehicle causing the ABS to randomly activate.

[vrg3]

That's a good point, ciper.

Check that all the wheels are tight on the hub, and that all six holes (the five for the lug studs and the one for the hub center) fit correctly. If your car ever had loose lug nuts or something, it's actually possible that they could round out some of the lug holes on the wheels enough that the wheel could turn irregularly, upsetting the ABS sensor (and eventually causing lots of other problems).

[HomeSlice]

also try blowing off all the sensors at the wheels. since they are magnetic it attracts alot of metal particles. one may just be fouled up a little.

[LegacyT]

Is the abs spose to turn off and on by itself? When I'm in deep snow, or say doing drifts for awhile, the abs light comes on and the system is deactivated. As soon as I turn the ignition off and on again the light will go out and The abs is reactivated. Is this normal?

Thanks,
Mark

[Legacy777]

You're probably getting moisture in the sensor, and it freaks out and turns the abs off.

When you turn the car off the abs computer comes back on, does a diag. and if everything checks out ok, it starts up as normal.

[ciper]

vrg3: I guess my less than technical term was too vague, did you think I meant the wheel/rim?

I meant make sure that the ring used to sense wheel speed is firmly attached to the hub

[vrg3]

Huh... I don't remember what I thought. I think I understood what you said, and was saying that it was a good point. It also reminded me to suggest checking the rim. I should have delimited those two thoughts better.