Last night my rear ABS light came on after driving for a bit. When I started the truck this morning, it was off, but came on soon after. As far as I can tell the brakes aren't doing anything out of the ordinary, so I can't figure out why it's on, any ideas? It's a 92 F150.

 

Most likely the speed sensor on top of the rear axle, but without pulling codes this is just a SWAG (scientific wild a** guess) but was a frequent problem on older Fords used by U-Haul when I worked for them.

 

ABS lighting is just something Fords do (in my opinion). All of the ford trucks I've owned have had the ABS light come on at some time or another. Some lit up just once, some for a few days, and some forever. I just learned to ignore it. You can always take the ABS bulb out if the light bothers you. I'm not a big fan of the ABS system anyways. Good luck.

 

The ABS light is supposed to come on for 1-2 seconds when you start the truck to show you that the bulb is working. Then it goes off for a couple seconds and only comes on again if the ABS module detects a problem with the ABS system. It's telling you that something is wrong, and the ABS system is not working. You won't be able to tell the difference until you get in a situation where you are braking hard enough to lock up the rear wheels; e.g., slick streets and a panic stop.

My advice: pull the codes and fix the problem. ABS works. Rear ABS is important on a truck, which is so light in the rear end when not loaded.

To pull the codes, locate the connector beneath your glove box that has a black/orange stripe wire going in one side and a red wire going in the other side. Turn the key to the "on" position (without the engine running), disconnect the two sides of the connector, and ground the black/orange stripe side of the connector for 1-2 seconds. The ABS light will begin flashing out the code corresponding to the ABS problem. It will pause and repeat the code. Count the flashes a few times to make sure you have the count correct. The number of flashes correpsonds to the code of the problem the ABS module has detected.

You can find a troubleshooting procedure (the same as the AllData one) on Autozone's site if you click through the links for the "Repair Data" they provide free on their site.

There was an error in the procedure listed for my truck ('94) for pinpoint test number 7, though, so I can't guarantee there won't be other errors in there for your truck. The factory service manual is the way to go if you have access to one. If you don't post your error code on here and someone will probably help you out with the procedure.

Good luck with it.

 

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