E4od code 29

[Themudgician]

Hi im getting a intermittent code 29 with harsh shifts. Some days its fine other days i cant make it out of my driveway without slamming in gear. My speedometer always seems to be working fine and is always steady. I pulled the psom module out and couldnt see any burnt parts. Anybody have any ideas or maybe wiring diagrams. Truck is a 1994 idit. Thanks for any help.

 

[gandalf]

My code list shows that code 29 is "insufficient VSS input". On my '92 CCLB the VSS is located on the rear differential, front side, upper portion. I'd check that first, maybe even replace it.

 

[Themudgician]

Just letting everyone know i figured out what was causing the code 29 ( loss of vss signal to pcm ) it was the psom module on back of the speedometer. I got a replacement speedometer at junk yard and she shifts like brand new again.

 

[gandalf]

That's good. Thanks for letting us know of the successful fix.