Engine/Transmission (1998.5 - 2002) Speedometer jumping and ABS/Brake light on

[JFulford]

My buddy has a 99 LB single cab 4wd, rearwheel ABS.

We just swapped the clutch and had the NV4500 rebuilt. Installation went well and we got it all back together without a problem.

After 2 days, the ABS/brake light came on and stayed while driving, and the speedometer is jumping around above 40mph.

The rear sensor was replace a few years ago for another speedometer issue(jumping around Below 40mph). We just replaced the sensor and it made no difference.

The truck has 270K on it.

Any suggestions?

Thanks,

jeff

 

[Joe Mc]

My gut was telling me the sensor in the rear, but that was just replaced w/no change . . . Maybe check the wiring to and from the sensor, something got disturbed during the recent work?

 

[JFulford]

Speedo jump

Yeah, that's what we thought too. I'm having my friend check the wiring and will post more when I hear from him.

jeff

 

[JFulford]

Speedometer jumping

My friend reported that the ABS/Brake light stayed off 1/2 way to work this morning until he hit a pothole, then they popped back on. The speedometer worked his entire drive, which is about a 70 mile oneway trip.



So it looks like it is a connection issue. Does anyone know if there are any more connection points between the rear sensor and the computer up front?

Thanks

jeff

 

[SSolderitch]

if you meter the connector at the abs that will prove out all rear wiring. There is also a cc buss wire that goes accross to the pcm. When I had my abs & brake light come on - every other day - after driving 10 miles, changed the sensor, only to find a bad Master cylinder. To check unplug portportion valve switch wire. If the Light stays off, then a bad MC.

 

[JFulford]

Well, it turned out that is was a bad connection/broken wire. Here's a link to the pictures:
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Thanks for the help on this.
jeff