Recently my ABS light comes on. Everything appears to be working OK. What the most common reason for this?

old and tired wires to and from the wheels sensors

They are NOLA, but wiring can be repaired or volvo sensors can be used.

Just had one of my rears done by Pete (user id: ElGreco) on here

Does it come on right away with engine start, or after a few minutes of driving?

1. Right away: Power issue ( think relay or fuse), shorted or open sensor wheel sensor wire.
2. After driving: Poor signal from sensor(s)

Could be other things as well, but above are a good start.

There isn't much on this car that is old. The front brakes are GTS "BiG Blacks" and everything in the front suspension is new ( 17,000 miles )
Rears look OK however I will dive into it
The light comes on at start up. I'll check the relay

Thanks
Van

Fuse 16 Antilock Braking System

Rats! #16 fuse is OK and there isn't a relay for ABS. Gotta be in the rear.

You also have two relays in the abs hydraulic unit, the silver one is prone to failure. Highly expensive also unless you get with Roger who has an alternative.

I had same problem in my 87. Checked all the things suggested above and ABS still on. Bought a used ABS control module for $50, swapped it in and light off after start up. I have tested it with hard braking and let the ABS light in those circumstances.

Kevin

The light does not go on right away. Once started and warmed up enough to proceed it will come on in about 30 seconds. Is it possible to check the XVII relay before spending a $125?

Car is stationary when the light comes on?

Before going bananas replacing relays, put the car up on a lift or something and check every wheel. Follow the wire from the ABS sensor on the wheel through the several grommets that keep it from hitting the body/axles/cv joints/etc. Those grommets decompose, which allows the wire harness to fall on something, wear through, and cause a ground-out.

It's not that hard to do. I wound up replacing all the grommets, and have not had a brake pad or ABS error since.

Sometimes it will come on before moving, sometimes not

I was just under the car looking for any kind of evidence of rubbing etc. This is only a 17k mile ( 2 year old) car and there isn't much dust or dirt or anything crusty under it.

This is your Porsche 928?

Kevin, this is his fire car that Greg Brown pretty much rebuilt from the ground up.