1993 ABS Codes - No Faults Then Suddenly Many Codes

[Tshark299]

Never had a fault with the ABS in 22 years. ABS functioned properly last time it was driven; parked it for 3 days, now the ABS light remains lit after turning the key to ON with multiple fault codes. I did some searching but most threads on ABS issues seem to end inconclusively so figured maybe I'd try again here.

1st time I pulled the codes I got (in this order):
17 - Reference Voltage
11 - ECU Failure
31 - Front Left Sensor Electrical Failure
67 - Pump Motor

2nd time:
17
11
32 - Front Right Sensor Electrical Failure
67

3rd time all the same except back to 31, then 4th through like 8th time all the same except back to 32.

I then disconnect both front sensors and get BOTH 31 and 32 (in addition to the others), which makes sense.

I clean up the connectors, reconnect both, but still get both 31 and 32 in addition to the others, which doesn't make as much sense.

Tried disconnecting, cleaning, and reconnecting the module connector but no change. Still now getting 17, 11, 31, 32, and 67.

So, does it seem like my module has in fact suddenly gone bad? It seems strange to me that there are so many faults when the system was fully working the last time it was driven, but I have very little experience with how these things go bad. Are there any other tests I can perform, besides swapping out the control module? Thanks for any help.

 

[Maniak]

I'm no ABS expert (I turned off the ABS on our '92 many years ago) but I don't like seeing the code 11.

All the rest of the codes I could see happening if you had some chewed wires. That is something I run across occasionally out this way.. Damn packrats...

I would check the under hood harness, specifically the section heading to the ABS controller. If you are lucky you'll find it was rubbing on something or something ate through it.

~Mark

 

[Tshark299]

I'm no ABS expert (I turned off the ABS on our '92 many years ago) but I don't like seeing the code 11.

All the rest of the codes I could see happening if you had some chewed wires. That is something I run across occasionally out this way.. Damn packrats...

I would check the under hood harness, specifically the section heading to the ABS controller. If you are lucky you'll find it was rubbing on something or something ate through it.

~Mark

I didn't see any wires that looked compromised when I was last poking around there, but it was getting late so I will take a closer look with better light when I get a chance. I'm pretty sure everything is intact though.

Between the multitude of codes so suddenly and the inconsistency that I'm getting some of them, my logic (limited as it is in this area) is leaning toward the control module going bad. Assuming the wiring looks good, I think I might spend the few extra bucks and order a module from the local parts store to swap in, so that if it doesn't solve the problem I can easily return it.

 

[Tshark299]

I took a closer look around the sensors and the control module and didn't see any suspect wiring.

I picked up a reman'd module from the the parts store. I still get a lot codes but now half of them are different. I lost 17 and 31, but gained 41, 42, and 55:

11 - ECU Failure
32 - Front Right Sensor Electrical Failure
41 - Front Left Sensor Mismatched Output
42 - Front Right Sensor Mismatched Output
55 - Front Left Sensor Output Dropout
67 - Pump Motor

The new module says it was tested good when it left the factory, supposedly, yet I still get the ECU Failure code. If I plug in the old module again I get all its original codes still, and yet the new one repeatedly gives these new codes. I also read that these new codes (41, 42, 55) are only supposed to be thrown when it runs additional checks after reaching certain speeds, yet I'm getting them immediately after turning the key to ON.

Another potentially bad module, right out of the box? Does anyone have a source for troubleshooting procedures related to these codes, so I can more definitively identify the module itself as the problem? Any other ideas would be appreciated as well.