Per my last post, while replacing the leaf spring bushings and messing with the rear end, as I was jacking up the axle the jack rolled down my driveway causing the axle to drop down to the ground. I'm assuming that this somehow damaged the RWAL sensor and/or wiring that leads to it since when I got everything bolted up and took it for a drive my ABS and parking brake lights illuminated once I got up to speed. I also noticed that my brake lights were constantly illuminated even with the keys out of the ignition.

I did some digging on some older posts on here and have done the following diagnostics and replaced the following parts:

1. Ensured brake fluid was topped off and there wasn't a leak in the master cylinder
   1. Master cylinder was replaced and the entire system bled ~1 month ago
2. Checked and verified that all associated fuses weren't blown
3. Replaced RWAL sensor
4. Inspected the wiring and loom leading to the RWAL sensor
   1. The loom was cracked and damaged (I imagine from age and when the axle dropped off the jack) but the wires were undamaged
5. Verified that the positive (white and violet) and negative (red and violet) wires did not have a short to ground
   1. Confirmed this at both the ABS module under the hood and at the RWAL sensor
   2. To my knowledge this sensor actually generates a small current and thus won't have any voltage supplied to it, which was verified with the key in the ignition set to accessory.
6. My speedometer functions as it should.

The above issues are all still present so I'm not sure if there's a section in the service manual that I missed or couldn't find regarding diagnostics for this issue but I can't seem to figure out what's going on. My only current idea is that when the axle dropped it stretched out the wires leading to the RWAL sensor internally, just enough to sever the connection but not enough to completely rip the insulation. Any ideas?

 

I believe it is supposed to get a five volt feed from the PCM.....

With the brake lights staying on though, I would more suspect a bad brake switch. That'll turn the lights on too.

 

I agree, the brake lights staying on is weird -- almost feels like two separate problems.

I might chase that down first, although it's odd it started after the axle/jack incident

 

Also I feel your pain, I recently had a leaf pack fall off a rear axle and sever a rear WSS harness. Fortunately I put it back together with heat shrink butt connectors and it worked perfectly

 

So if I didn't get any voltage reading from the connector at the sensor when the keys were in the ignition and set to accessory then I might have an issue with the wiring? I confirmed it isn't shorting to ground so perhaps it's damaged somewhere?

Also the brake switch is the sensor under the dashboard by the brake pedal correct?

 

I don't know if its actually powered in accessory mode.... Should see voltage with ignition on though. (run position.)

 

After inspecting the brake light sensor I saw the the plastic rod on the sensor was cracked and didn't really move with the brake pedal anymore; replaced it and now I have no issue with the brake lights.

The ABS light has also mysteriously disappeared; I cleaned the electrical connections again and took readings at both the RWAL sensor and the ABS module connector with the keys in and on run/accessory:
4.84V (positive) 0 V (negative) at RWAL sensor (not sure why I'm now getting a signal here when I didn't several days ago, unless a wire is loose somewhere?)
Wire #1 @ ABS module 0V (one of the RWAL senor wires)
Wire #2 @ ABS module 10.25V
Wire #3 @ ABS module 2.5V
Wire #4 @ ABS module 12.33V
Wire #5 @ ABS module 0V
Wire #6 @ ABS module 0V
Wire #7 @ ABS module 12.35V
Wire #8 @ ABS module 0V (one of the RWAL senor wires)
Wire #9 @ ABS module 12.25V
Wire #10 @ ABS module 2.5V
Wire #12 @ ABS module 5.12V
Wire #13 @ ABS module 0V
Wire #14 @ ABS module 12.35V

HeyYou was indeed correct, the RWAL sensor does indeed receive a 5V signal, but according to the manual that signal is on wires #1 and #8 of the ABS harness so I'm a tad confused as to how everything is magically working now when the wires that are supposedly supplying the sensor with power didn't have power themselves. The corresponding connections on the ABS module itself also did not have power. In any event I'm just happy everything is now suddenly working. Thanks all for the assistance!