My ABS and Parking brake light are still on. Previous owner said that the a wheel cylinder failed and the pedal went to the floor, and the light has been on ever since since.

My trouble code flashes 7 times (8 times if you include the long flash at the end).

I can find no fuse that is blown.

I have replaced the ABS sensor in the differential.

I have reset/unplugged the BCM many times.

Master cyl leaks from the top cover gasket sometimes. How full is it supposed to be?

I was thinking about bleeding the brakes again.

Any Ideas for me to try?

 

APD, if your truck is like mine, you will find a wiring harness under the dash on the driver’s side. If memory serves me right, it has two wires connected to it. This is connected to the rear axle speed sensor, and is used at the factory for installation and setup. I think it might be a good way to see if the rear axle sensor is working. If you want, I could try taking some voltage readings off of it while driving at specified speeds, to give you some reference voltages. Let me know.

Also, what code would low vacuum give? Are you sure the vacuum switch is OK?

 

As I recall you are supposed to count the long flash -- I thought the trouble codes were listed in the tech faq's, but I can't find them

 

Long flash is not counted. It's there to signal the following flashes are the trouble code. I posted all the codes I had for the 91.5 already.

Isn't there a bleed screw right on the RWAL deal on the frame rail back by the axle?
Maybe give that a try too.


Den

 

APD, I took some readings. I'm not sure what we're supposed to be looking for here, or if an oscilloscope is needed, but this is a start. These voltages were taken from the two pin connector under the dash located immediately next to the hood release.

Key off = 0.0 VDC
Key on = 0.2
15 mph = 0.5
25 mph = 0.6
50 mph = 0.75
75 mph = 0.75

Also, the voltage would increase to 1.0 VDC when slowing down while traveling at highway speeds.

 

From '91 FSM:

FAULT CODE IDENTIFICATION

“The initial flash will be a long flash followed by a number of short flashes. The long flash indicates the beginning of the fault number sequence and the short flashes are a continuation of that sequence. You must count the long flash along with the short flashes for an accurate fault code count. ”

Chrysler even wrote it in bold.