Hello gentlemen, (and im sure there are a few ladies out there too). I just recently bought a 1997 F-150 Ext. cab 4x4 w/ the 4.6 w/ 184k on it. I bought it with an ABS light on, Im pretty versed in ABS issues from working on land rovers and volvo's but I have not worked on to many ford ABS systems, and I do not have the tool to read the codes. How do you all recommend I go about diagnosing the issue. Please let me know what your all's thoughts are, I appreciate it. Thanks.

 

Getting codes first will save you a lot of time. But you can test each wheel speed sensor manually by jacking the truck and watching sensor voltage (this is a low AC voltage). It should increase with more wheel speed. For the rear you'll need to support the truck and run engine while in D to turn wheels.
This can be kinda dangerous (driveshaft spinning while you're under it), so be careful.
Also, a wheel speed sensor will usually not turn the light on unless the vehicle is being driven. If you start the engine and let it idle in park, and the light comes on without moving it, your problem is likely not a wheel speed sensor. If this is the case-you'll need to scan. Also check the ABS fuse in the underhood fuse/relay panel.

 

So i started working on the truck and i replaced the rear sensor, (just becasue it was real cheap), that did not fix the issue. the abs light comes on before the truck moves. I just started looking at fuses and such and all are good, but I cant seem to find where the abs relay is. plus i looked and the owners manual said there should be a rear abs diode, and for some reason there is not one, nor wires for one. So if someone knows where I could find a wiring diagram thatd help alot. Also, do all these trucks need a diode? and where does the wiring for it go?

 

Did you drive the truck after replacing the VSS? Just put a new VSS in an F350 and it took a few miles to register and shut the light off...

 

I just drove about 30 miles and no go. any other ideas, id rather not go get the code read. I have to replace some lights in the instrument cluster anyway and so i might just pull the abs bulb out behind.

 

I take it you also inspected the wires up front? A scarred wire jacket or broken wire can cause an issue...

 

I did, I unplugged the wires to the module and cleaned the contacts and replaced them. Id really like for the abs to work on this truck but im not looking forward to get the codes read once for 80 bucks.

 

The VSS and the rear sensor are not the same thing. The VSS is on the transmission. The rear ABS sensor is on the diff. Either one can cause an ABS light to come on but the VSS can also cause a service engine soon light to come on. If your light comes on without moving the truck, I'd start by looking at something other than a speed sensor.

 

Most all parts stores list the rear ABS sensor as "vehicle speed sensor" and the vehicle speed sensor listed as "Transmission speed sensor", I have learned to label parts to what the parts stores list them as to avoid confusion...

 

I have the same problem but I have a B1206 code showing. Any takers?