I have a 95 that has rear only ABS. First noted a problem about a week ago. The ABS and brake light came on. I pulled the rear speed sensor, put it on a multimeter and it checked out OK. The speedometer and cruise work fine. Lights reset after the truck is killed but will light again after 10-15 minutes. When they are off, the truck seems to be engaging the anti-lock mechanism at all stops whether harsh or not. You can feel the system dumping pressure. Once the lights come on the brakes work fine because, I suppose, the ABS system is bypassed. I replaced the speed sensor since I've heard of intermittent problems. No change. Wires look fine. Has anyone else experienced this?

 

The most common problems are the wiring from the rear sensor up to the RWAL controller.
Step 1: There is a short harness that goes from the sensor over to the frame rail. Unplug it at both ends. Use an ohmmeter and make sure there is absolutely no continuity between the two wires (twisted pair) in this harness. If there is, it must be replaced. If not, clean and dry these connectors and put them all together. Move on two step 2.

Step 2: Unplug the sensor and measure its resistance- usually 1600-1800 ohms. Plug it back in. Unplug the RWAL controller, I think on a 95 it's behind the dash to the right of the driver's knee bolster. Find the two wires that lead to the sensor- (sorry I don't have the pinout here) Measure the resistance between the two, it should be the same as sensor resistance measured earlier, within a couple ohms. If not, search out your wiring problem, with extra attention to 2 connectors under the left front fender, behind the wheel.

These are the most common problems. I have also seen one with a couple teeth chewed off the tone wheel in the differential.
Hope this helps.

 

You know,we may be jumping the gun here. There is a wire you can ground to get the abs light to flash diagnostic codes. Your problem sounds like a sensor issue but we should make sure. I can't remember where under the dash the wire is but I think you could find it on a search here.

 

Tourquefan

I have followed step one and two you outlined and everything checks out good. I have a Haynes manual that calls for a 16 port data link under the dash but I can find no such animal (to flash codes). My truck is a 95 and what I have our 2 links a 4 and a 7 wire I believe. Anyone retrieved the ABS codes on a 95??

 

see my reply in the other section where you posted on this.........