My speedo is driving me crazy. It will lie flat at zero, then jump sporadically, primarily when I hit a bump. Then sometimes, I can hit a pothole just right and it will work for a few miles, then go dead again. My ABS light comes on, and sometimes after a while the red brake light. I have tried cleaning the connectors, and even soldered the joint behind the drivers tire solid. I removed the working speed sensor from my downed 2001 and installed it, and even cleaned the ground strap leading to the pcm frame. It is making me backfire and stall at stop lights. I have a manual, so I only have the one sensor. Any thoughts?

 

Check speed sensor on transmission. May be loose or wire damaged. Also check RAWL sensor on diff.

 

Does the manual trans have an output speed sensor?

 

I believe so. There was another thread posted this evening about that. Mine is auto, so I have no first hand knowledge....That poster was looking for neutral safety swith I believe.

 

No, absolutely no sensor on the tranny. The only thing with a wire is the backup switch. The RWAL sensor is also the Vehicle Speed Sensor on a manual.

 

seroiusly, please chime in. If I don't fix this quickly, I will buy a kumquat and beat the mess out of my truck... My muffler can't take many more backfires and my exhaust manifolds are leaking now

 

I think you have two different problems....

Check the connector at the sensor, make sure it is clean and tight. If a known good sensor STILL doesn't wanna work right, check the connectors at the PCM, they like to corrode up some too....

Once that is dealt with, see if you still have the backfiring problem.

 

Okay, I'm at a loss. I reviewed the PDF on the 2001 Tech manual, and it appears that the ABS module drives the RWAL sensor, converts that to a signal, and relays that to the ECM. I unplugged the harness from the ABS module, and the sensor read 1.9 ohms. Good, right? Then I checked the wire feeding the ECM. It is good all the way to the PCM. Then I pulled the ABS module from my downed truck (working) and installed it. Still no good. Any thoughts?

 

2 or 4 wheel abs?

 

2 wheel, just rear wheel ABS