P0500 Check engine light with occasional ABS

[NPdarkside21]

I have a '99 3.0V6 FlexFuel and my check engine light is on for a P0500 code. I have replaced the VSS on the differential but the code still remains. The truck has been sitting but there's no evidence of rodents or damage to the main harness. I am trying to trace the wiring to find the issue but I cannot see anything obvious. Are there any key places, wires, pigtails, or harness points to check?

 

[rusty ol ranger]

Check the harness for breaks/corrosion.

But i do know on the fullsize trucks the tone ring (what the VSS reads from inside the rear end) can wear out and screw with stuff

 

[NPdarkside21]

I traced the red/pink and black/green from the VSS all the way to the PCM and found no issues. I used a voltmeter to check for continuity throughout it all and there were no issues. I'm wondering if it is my PCM. I mean I'm hoping it's not. The only thing I did to it before even touching any of this was change the fuel pump. It was throwing a code for a fuel level sensor only (pending and stored). I'm running out of ideas at this point.

 

[snoranger]

The most common issue we had on the older 3 channel systems (most of our fleet is newer true 4 wheel systems) was with the rear wheel speed sensor plug. Since down time is more costly than parts to us, we’d replace both the pigtail and the sensor.

 

[NPdarkside21]

could a failing abs module cause this? This truck only has 2 wheel ABS and tracing the wires led me to a connector that stays unplugged and capped at all times with the same corresponding colored wires to the differential mounted speed sensor. I changed the differential fluid not too long ago and after looking at the ABS/wheel speed tone ring there were no irregularities like metal shaving in the teeth or teeth missing.

 

[Burnsy]

Maybe splice in a new pigtail or check it with a device.....make sure pigtail is on correctly, they're a little funky with the design and how it goes together....the sleave of either the pigtail or the sensor, can't recall exactly, has to slide under a little lip to go on snug.....if it doesn't slide under the lip it won't go on all the way....thats probably not your issue but double check.......on my 01 3.0 theres also a trans sensor that goes on top of the tranny near the rear of it...it is the same exact shape as the rear axle sensor but a tad smaller if I remember correctly...takes a star shaped socket to take off the one bolt holding it on....using a small handheld mirror can help you find and work on it....not sure it has any bearing on your problem....im not a great mechanic ive just kept my trucks running by having some knowledge and help from others etc