ABS light

[Mike Y]

The ABS light in my car (95 Pontiac GP) is on. Most of the time.
Occasionally it will go on and then turn off on a start, but that's
rare.

The auto-store manuals suggest that I can't get at the individual
ABS error codes without an interactive module. I can't just
dump the error codes like I can do with the engine codes.

One individual suggested it was a speed sensor at the wheel
being slightly bent. The previous owner did a brake just himself
just before he sold it to me and replaced the 2 rear rotors and
one caliper. So that's my first point of investigation.

Any tips?

[Mike Walsh]

A bent or otherwise misadjusted speed sensor will not cause a problem until the vehicle is in motion. If the light is always on it could be a shorted or loose connection at a speed sensor. A bad alternator (over voltage) can give a ABS fault.

Post by Mike Y
The ABS light in my car (95 Pontiac GP) is on. Most of the time.
Occasionally it will go on and then turn off on a start, but that's
rare.
The auto-store manuals suggest that I can't get at the individual
ABS error codes without an interactive module. I can't just
dump the error codes like I can do with the engine codes.
One individual suggested it was a speed sensor at the wheel
being slightly bent. The previous owner did a brake just himself
just before he sold it to me and replaced the 2 rear rotors and
one caliper. So that's my first point of investigation.
Any tips?

[Mike Y]

It seems to be 'always on' most of the time. However, twice now, I've
I'll turn the key on and the lights all display on the dash, then the brake
light goes out, then the ABS light goes out. Both times that happened
was after I just drove somewhere and I had shut the motor off and then
turned it back on. I'm going to try to see if it behaves that way tonight.
The other key thing is both times it went out was when I did NOT start
the motor, but just turn the key to on and waited a few seconds. In the
morning I'm usually a 'turn and go', with my foot on the brake immediately
to take the car out of park and get out the driveway. I'm going to see if
I can come up with a scenario that lets it NOT fail and then see if there's
anything I can do. Or if I can get the light to go out, then start the car
and move it and see if it goes on. If it's a bent or misaligned sensor, it
should turn the light on when I pull out, right?

Mike

Post by Mike Walsh
A bent or otherwise misadjusted speed sensor will not cause a problem

until the vehicle is in motion. If the light is always on it could be a
shorted or loose connection at a speed sensor. A bad alternator (over
voltage) can give a ABS fault.

Post by Mike Walsh

Post by Mike Y
The ABS light in my car (95 Pontiac GP) is on. Most of the time.
Occasionally it will go on and then turn off on a start, but that's
rare.
The auto-store manuals suggest that I can't get at the individual
ABS error codes without an interactive module. I can't just
dump the error codes like I can do with the engine codes.
One individual suggested it was a speed sensor at the wheel
being slightly bent. The previous owner did a brake just himself
just before he sold it to me and replaced the 2 rear rotors and
one caliper. So that's my first point of investigation.
Any tips?

--
Mike Walsh
West Palm Beach, Florida, U.S.A.

[Mike Walsh]

If the wheel speed sensor is misaligned or otherwise not functioning a fault will appear when the computer determines that the sensor is not producing nearly as many pulses as a functioning sensor. This might not occur as soon as you pull out, but it should occur in less than a mile.

Post by Mike Y
It seems to be 'always on' most of the time. However, twice now, I've
I'll turn the key on and the lights all display on the dash, then the brake
light goes out, then the ABS light goes out. Both times that happened
was after I just drove somewhere and I had shut the motor off and then
turned it back on. I'm going to try to see if it behaves that way tonight.
The other key thing is both times it went out was when I did NOT start
the motor, but just turn the key to on and waited a few seconds. In the
morning I'm usually a 'turn and go', with my foot on the brake immediately
to take the car out of park and get out the driveway. I'm going to see if
I can come up with a scenario that lets it NOT fail and then see if there's
anything I can do. Or if I can get the light to go out, then start the car
and move it and see if it goes on. If it's a bent or misaligned sensor, it
should turn the light on when I pull out, right?
Mike

Post by Mike Walsh
A bent or otherwise misadjusted speed sensor will not cause a problem

until the vehicle is in motion. If the light is always on it could be a
shorted or loose connection at a speed sensor. A bad alternator (over
voltage) can give a ABS fault.

Post by Mike Walsh

Post by Mike Y
The ABS light in my car (95 Pontiac GP) is on. Most of the time.
Occasionally it will go on and then turn off on a start, but that's
rare.
The auto-store manuals suggest that I can't get at the individual
ABS error codes without an interactive module. I can't just
dump the error codes like I can do with the engine codes.
One individual suggested it was a speed sensor at the wheel
being slightly bent. The previous owner did a brake just himself
just before he sold it to me and replaced the 2 rear rotors and
one caliper. So that's my first point of investigation.
Any tips?

--
Mike Walsh
West Palm Beach, Florida, U.S.A.