Background:
The abs inop has been illuminated on my car for over a year. Occasionally it would go away; however, when it went away the brake light would come on and stay on. Then, eventually the abs inop light would come back on and the brake light would go off.

The car is in my sig with the three channel abs.

Had my abs module scanned by a shop a few weeks ago and they came up with the following codes:

DTC 11 ABS Warning lamp circuit malfunction
DTC 24 Right rear wheel speed=0
DTC 32 LF Wheel Speed CKT open/short to grd/batt
DTC 36 Low system voltage
DTC 87 Red brake warning lamp circuit open

I have ordered the hub assembly for the LF sensor the the sensor that goes on top of the differential as well. The shop concluded I also need a new proportioning valve and a new(working) ABS module.

Can anyone confirm or dismiss their conclusion based on the listed DTC's?

Thanks,

Nick

 

I've seen guys have similar issues and DTC codes with electrical system problems. Check all your chasis grounds and clean them and also check your battery and Alternator output as this was the most common problem.

Also, check your third brake light as it can cause the DTC 87 you are seeing when it's burned out or the socket has some corrosion.

 

Thanks for the good info.

 

Does anyone have experience replacing the EBCM and proportioning valve themselves? If so, would you care to share your experience and whether it was worth doing it yourself?

Thanks,

Nick

 

All the codes seem to point to "external" components - wheel sensors, dash light, system voltage. I don't see a code that indicates a problem with the ABS motor module.

The open in the "BRAKE" lamp system could be wiring, or it could be the pressure switch on the side of the ABS module. But that is replaceable.

 

I replaced the two sensors located at the front left and rear differential. The car now only displays the brake light constantly. If I recall correctly Injuneer, you posted this indicates a pressure differential between front and rear of the system? Which connector is the pressure switch?

Nick

 

On the ABS motor unit, on the side facing the engine, there is a block where the two lines from the brake master cylinder connect on top of the block. The pressure switch on mounted on the top of the block, between the two lines.

 

Thanks for providing the location.

I found something else that's interesting.

The dash brake light is on and the spoiler brake light bulbs illuminate correctly and the switch for the hand brake is clean.

It snowed here some this week so I thought it would be a good opportunity to do some brake testing at low speeds. The front wheels will lock up but the rears will not. Image: Man driving car slamming on brakes while holding head out the window. Although, I can lock the rears up with the hand brake. Does this indicate a bad master cylinder?

Also, where can a pressure switch be found for purchase and what is the approximate price for one?