I bought a 1997 chevrolet 2500 4 wheel drive that now will not shift out of 1st gear no check engine lite fluid looks and smells ok truck only has 80,000 miles 4l80e tranny any ideas would be welcome Terry

 

Does the speedometer work okay?

Allan

 

works part time

 

Okay,<O</O
<O</O

The common denominator here is the VSS at the transfer case. 4X4 models use the output shaft speed of the transfer case, not the transmission output shaft sensor.
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That's sure where I'd start.<O</O
<O</O

Allan<O</O

 

I just drove the truck and when the speedo and tach quit the trans will shift. When the speedo starts to work the trans down shifts and will not upshift. Is that weird? Help

 

Has it ever shifted okay since you've owned it?

Sounds like someone swapped in a 4L80 in place of a 4L60 and didn't change the wiring.

Allan

 

I found that the voltage on the trans fuse would drop from 12v to 3v when the truck was running. After checking and by passing the original wiring the truck would shift and the tach and speedo would all work. Found the ignition switch bad. thanks for the help and suggestions. Terry