ABS diagnosis....where to start.

[Jason89i]

I have had the ABS light go on (ABS is turning off) after getting car up past 30mph. Restarting car resets system. I have also noticed that going at low speed while slightly applying brake causes ABS pump to slightly pump.

No freyed wires, did not notice any debris in abs cog (toothed wheel on hub.) Where should i start?

On a side note.....it happened on my second to last session at the track. Threshold braking on a track is not as easy as on the street. Changes in track surface can really play with car dynamics that ABS can mask.

Cheers,
Jason

[clavinZERO]

how bout a hearty BUMP.

[James Crivellone]

Check the 2 yellow round connectors under the rear seat, they love to come undone once in a blue moon.

Could be a bumb sensor, or faulty ABS Relay

[AdamF 88iS]

Since it happens when you are rolling I would guess that it is a sensor problem. To figure out which sensor it is, you need to disconnect all except for one of the sensors and drive to 30mph. If the light still comes on try leaving a different one plugged in. Which ever sensor is plugged in when the light stops coming on is the one with the problem. Basically the car will think it is still stopped with 3 unplugged + one bad sensor and thus the light will never appear.

[e30evolution]

wont the light come on if any sensors are unplugged?... or do you mean taken away from the tone ring?

[AdamF 88iS]

wont the light come on if any sensors are unplugged?... or do you mean taken away from the tone ring?

Honestly I dont remember. You may even have to unplug the speedo sensor as well. But the basic point of my method will work. It's a little different for all the different models but I'm pretty sure that the computer will read an unplugged sensor as a 0mph signal on E30s.