I have a 1999 F150 that is my baby. She has almost a quarter million miles and the only thing replaced so far is alternator, brake pads, tires, and battery. It has RWABS only, 4.2l 5-speed standard.
Problem: About two weeks ago, I took her to discount tire for a new set of rubbers and those rocket scientists left my parking brake engaged when they drove from the front of the store into their garage. About two miles after I left, my ABS light came on. Auto zone said they could not retrieve diagnostic codes, and my CLYMER manual said something about orange wire and black wire to ground to make abs light flash and manually retrieve codes. I have no idea where these wires are. I have also read several threads and most people end up just cleaning or replacing speed sensor, I cannot find this bugger either. So, I am asking someone if they know where these wires are(supposed to be a connector) and where the rear speed sensor is, as I can just try cleaning it or replacing it. Except for changing tires, I am the only one who has ever worked on this truck, and I intend to keep it that way, so it will keep running as good as it does. I have learned in the past that if you want someone to be careful when they work on your vehicle, well that just isn't possible, you have to do it yourself. Can someone who knows more than me please educate me?

 

On top of the rear differential but closer to where the drive shaft pinion seal is.

 

The wires to trigger the self-test are behind the passenger kick panel.

Pull the rear diff sensor and check it for resistance. A good one will show around 1000-1500 ohms. When they fail, they usually open-circuit.

Seve

 

When they open circuit do they not read any ohms at all?

 

An open circuit reads infinite resistance.

A short circuit reads zero ohms.

 

I pulled the abs sensor and it was covered with a pasty-grey/metallic goop. I cleaned it and connected it to my meter. Does it depend on the axle to complete a ground? The reason I ask is that I got zero ohms.

Does that mean that there is a short circuit in the sensor itself? Could the gunk on the outside of the sensor short circiuted the sensor?

 

The sensor is magnetic, so the gray goo was metal shavings from the gears. As long as there were no chunks big enough to stick in your fingers, it's normal. No, that can't short the sensor.

But a big gouge in the sensor would indicate something broke loose inside & got chewed up, and I've seen THAT short the sensor.

If yours looks smooth (the part that goes into the diff) and doesn't have any blisters, it probably just failed due to age. Get a new one - they're fairly cheap.

 

How does one retrieve the diagnostic codes for the ABS light?

 

just run into any autozone or major parts store, and they will pull the codes for free

 

pazzo
Depends on the year. Put your truck's specs into your profile so they show in the gray bar.

 

Zero chance on that happening. You can't pull ABS codes with a sub-$200 scanner.

Steve