Thanks for the input guys.
Don, I don’t believe it is warped front rotors—I have had those before and replaced them last year. This is definitely pedal pulsations along with a low tone electronic clicking (for lack of a better audible description). I don’t think special tools are required. The module has a few plastic clips on it—easy to remove. I just have to be careful not to touch the terminals or let brake fluid get on them. If the
DRAC is bad, I would have to look for that—somewhere in the dash near the glove box I think. VSS seems easy to replace. Combination valve should be easy to if I had to replace it---just would have to ensure everything is bled correctly.
I yanked the wire from the combination valve and the same idiot light blinks---5 short, one long blink (6).
If something was amiss in the rear shoes, I guess it could confuse the sensors/readings going into the DRAC—but, since the cruise control and torque converter lockup feature work fine, I am shying away from speed sensors. I’m going to remove the rear wheels and drums just to inspect them—ensure the adjustment is fine and bigger shoe towards front. I believe there is only one speed sensor—I think the ’91 GM vehicles used the Kelsey-Hayes RWAL system. That sensor would be in the transmission with the ring in the tailshaft.
Kelsey-Hayes RWAL….
I wish this thing didn’t have RWAL---this is aggravating. I don’t have a code reader—perhaps that will be in the near future. In the meantime, I think I will replace the ABS control module.
Vile, i see what you mean about jumping codes...
"ABS Fault Code Access
On GM vehicles, fault codes can be retrieved manually (flash codes) by jumping terminals "A" and "H" (or grounding terminal "H") on the diagnostic connector, or you can use a scan tool such as a Tech 1 or Tech 2. On Ford and Dodge trucks, fault codes can be accessed manually by grounding the diagnostic pigtail connector on the ABS control module.
The flash code sequence for Ford, GM, Dodge and import trucks with the Kelsey-Hayes rear-wheel ABS system are the same, but the flash codes are slightly different. If you're reading flash codes, start counting from the first long flash. Then add the short flashes that follow. The total of the long flash plus any short flashes that follow equals the number of the code.
Because the system can only do one code at a time, the first code must be read out, diagnosed and repaired before the system can generate any additional codes.
Beginning in August 1990, a software change was made in the ABS controller on all General Motors RWAL equipped vehicles. The change transforms codes 6, 9 and 10 into "soft" (non-latching) codes that only illuminate the warming light as long as the fault is present. If the fault is intermittent and no longer exists, the light will go out with the next ignition cycle. The conditions under which the codes are set remains the same, as do the basic diagnostic procedures.
A scan tool must be used on the newer GM applications to read any soft (non-latching) codes that might be present because grounding the "H" terminal on the ALDL connector erases soft codes.
RWAL Fault codes
Codes for Dodge RWAL, Ford RABS and GM RWAL applications are similar but have a few differences:
1. Should not occur (replace the controller if it does)
2. Open isolation valve circuit or defective ABS module
3. Open dump valve circuit or defective ABS module
4. Grounded or closed RABS or RWAL valve switch
5. Excessive actuations of dump valve during ABS braking
6. Erratic speed sensor signal
7. Shorted isolation valve or defective ABS module
8. Shorter dump valve or defective ABS module
9. High resistance or open speed sensor circuit (resistance should be 1000 to 2500 ohms)
10. Low speed sensor resistance (Dodge & Ford only)
11. Open speed sensor circuit (GM only)
12. Stop lamp switch circuit (Dodge & Ford)
13. ABS module speed processor (Dodge & Ford only)
14. ABS module program (Dodge & Ford only)
15. ABS module RAM memory failure (Dodge & Ford)
To manually clear a stored fault code on GM and some Dodge trucks with RWAL, remove the ABS fuse or disconnect the battery for 5 seconds. Ford RABS codes will automatically clear when the ignition is turned to the off position"
I never tried this before, we'll see....