I had an ABS fault last Dec threw a bunch of codes I ended pretty much changing everything. Once I started getting into it that far it just made sense. Rock Auto sells the sensors they aren't exactly easy to change depending on the amount of corrosion on your front end.
I used a cheap OBD 1 reader it was 30 bucks at Canadian Tire but it works.
Here is some info I found when looking around
http://www.motor.com/article.asp?article_ID=45
As for testing the WSS you need to have access to a DVOM Here is the procedure
Trying to repair the sensor harness will most likely result in faulty signals. The resistance specification for each WSS is 1000 to 3000 ohms, which can be measured at the ECU connector.
For a more dynamic test, you can use a DVOM set to the AC scale. Just connect the meter at the sensor connector and rotate the wheel by hand. The output should exceed 400mV AC.
Read the article and have some questions.
I have never been able to solve my intermittent ABS Light, which is nearly always on. After the initial test cycle when I fire up the engine, the ABS light is always off. It usually comes on after rolling a short distance. Sometimes, it doesn't come on and the whole system works.
My brake pedal is spongy. I've always assumed that's just the way these trucks are. However, my son's '94 has a relatively hard brake pedal. So I read this article with great interest.
What's a DVOM?
What's the Brake Pressure Modulator?
>>> The Electronic Control Unit (ECU) of the 4WAL system is attached directly to the business part of the system-the Brake Pressure Modulator Valve (BPMV).
Service
Bleeding the BPMV is rather complex on the Kelsey-Hayes 4WAL system. A pressure or vacuum bleeder is preferred over using the brake pedal for this procedure. If the pedal must be used, consider removing the master cylinder to clean the reservoir, then bench bleed it to flush out any debris. If a new master cylinder is being installed, be sure to bleed it before installation. When vacuum or pedal bleeding, don't let the master cylinder reservoir run dry! Once air is bled from the master cylinder, the BPMV can be bled as follows:
1. Open the internal bleed screws a quarter- to a half-turn. These are the cap screws on either side of the BPMV.
2. Attach special tools (Kent-Moore No. J39177) to hold open the high-pressure accumulator bleed valves.
3. Open the two bleeder screws at the BPMV and bleed the unit.
4. Bleed the wheels in the following order: right rear, left rear, right front, left front.
5. Retighten the internal bleed screws and remove the tools from the high-pressure accumulators.
6. Firmly depress the brake pedal and perform three to six functional tests using either a scan tool or the jumper method described earlier. This forces remaining air from the BPMV into the lines running to the wheels.
7. Finally, bleed all four wheels again in the following order: right rear, left rear, right front, left front, to remove any air that was expelled from the BPMV. Note: This procedure should be necessary only if the BPMV is being replaced. During routine service, the system can be bled normally at the wheels.
If the BPMV is replaced and the procedure just described is not followed, air may be trapped in the hydraulic circuits that are normally not exposed to the regular braking system. Only after an ABS stop will this air be introduced. That means it may be days or even weeks after the fix that the customer returns with a spongy brake pedal complaint, not to mention one unhappy disposition. Now that's a sobering thought, isn't it?
Could the BPMV be the reason for my spongy brake pedal and ABS light coming on?
