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Jim Grant's Tech Tips
93 Chevy
Corsica, ABS Problems
Q: The Anti-Lock Brake System on my '93 Chevy Corsica comes on
all the time when stopping. There was a code for the left front speed
sensor and the sensor was replaced. No codes have returned, but The ABS
still comes on prematurely when stopping. I checked all of the sensors
and the AC voltage readings. Some vary at the same speed but the scan
tool reads all sensor speeds the same. Any ideas? .....George
A: I
don't think your problem is with a wheel speed sensor at this point. I
would suggest close inspection of the toner rings. The toner rings look
like a gear and are positioned just under the speed sensors. The toner
rings, in conjunction with the speed sensors, create a signal that informs
the ABS computer of wheel speed. Look for damage, it's likely that one
of the toner rings has a crack, bent or broken gear tooth, is loose or
has debris caught between the teeth. Something as simple as a crack in
the toner ring will cause the ABS system to falsely activate. That type
of problem cannot be seen with a computer scan tool, volt-meter or lab
scope. A human eye is the best inspection tool for this job.
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