What would cause my abs brake warning light to come on. It will come on and stay on for quite a while and then go off. Then it will come on again. '92 f-150 extended cab 6 cyl. 4x4 5 speed.

 

Start w/ the easy stuff. Sufficient fluid. Float not sticking, E-brake not hanging up.

 

Actually its my "rear ABS" warning light that comes on and off. Fluids are ok, float not sticking and e-brake is not hanging up.

 

Did you check the copper levels in your brake fluid? Copper is your brake systems arch nemesis. It wreaks havoc on sensors, calipers, wheel cylinders and master cylinders. Brake strips at the auto parts store are cheap, dip it and read it. You may just need to flush your brake fluid.

 

Any problems with your speedometer?

 

No, it is working fine. I was told there is a sensor on the rear diff. that goes bad. Is that true?

 

I have never heard of the copper problem. Where does it come from?

 

Others have reported wires breaking where it connects to the rear axle sensor. If that looks good remove sensor and check for foreign matter on the pick up.

 

It could be that sensor but if the speedometer is working then I doubt it. You can still check the wires to the sensor though. It may have separate feeds for the speedo and ABS. I don't remember how to check the ABS codes.

 

i've had the same issue. Other than replacing the Dif sensor I haven't seen anything else on these forums...It's a mystery.