my transmission

[matthew1962]

I have a 1994 chevy 1500 Silverado 4x4 stepside with the 6.5 turbo diesel ! I love it I have 300,000 and going strong but once in a while while going down the road at higher rpms the automatic transmission POPS OUT OF GEAR LIKE A MANUAL TRANSMISSION WOULD ! IF I STOP THE TRUCK SHUT IT OFF AND START IT BACK UP IT WILL RUN FINE ! WHATS THE PROBLEM ? AND WHAT TRANSMISSION IS IN THIS TRUCK ? CAN ANYONE HELP ME ?

[phantom309]

The transmission in your truck should be a 4l80e.

So to be clear on this,.

You say higher rpms,. just how high?

So you are cruising at say 60?mph, the transmission will suddenly free wheel like it is in neutral,.The rpms rev higher,.you lift your foot of the fuel pedal,. the engine returns to idle?,..You will roll to a stop,. and moving the shifter from park to 1st gear and back again will have no effect,.?? not even reverse?

Then you shut it off, start it back up,. and the trans works again,.?

OR,.is the converter unlocking and the rpms are climbing slightly,. and so you stop,. restart and all is ok,.

I need to know specifically,. because i,ve never heard of a 4l80e losing all gears,. to be reset by ignition on off,..

and yes we love to give free advice and help folks here,..

[matthew1962]

that's right between 60 and 70 0n freeway OR UNDER STRESS LIKE PULLING A BOAT IT WILL FREE WHEEL ! LIKE A MANUAL TRANNY POPPING OUT OF GEAR ! THE ONLY REMEDY IS TO SHUT IT OFF AND RESTART IT ! HAVE TO COME TO COMPLETE STOP ! PUT IT IN PSRK SHUT IT OFF THEN RESTART IT !

[Dvldog8793]

Howdy
Are you throwing any codes?
It also sounds like it might be a throttle pedal issue, but that is a triple redundancy system and will normally throw a code. BUT....I have had one go out with no code and when it failed the truck acted similar to what you describe. This would not normally be load specific.
The trans in your truck should be a fly-by-wire and the is a large connector on it that could have some corrosion/connection issues.
I think if it was a major component slippage you should get a code and limp mode and it would have failed completely by now.

[phantom309]

that's right between 60 and 70 0n freeway OR UNDER STRESS LIKE PULLING A BOAT IT WILL FREE WHEEL ! LIKE A MANUAL TRANNY POPPING OUT OF GEAR ! THE ONLY REMEDY IS TO SHUT IT OFF AND RESTART IT ! HAVE TO COME TO COMPLETE STOP ! PUT IT IN PSRK SHUT IT OFF THEN RESTART IT !

Interesting,. i have no idea,. because a 4l80e will default to 2nd gear if it see;s no ecm input,..

I think you need to look at the problem a little closer and report back,.. with the caps turned off.

[matthew1962]

thank you

[matthew1962]

well maybe a quencadence but I changed the pdm because I felt it was time and I druve 100 miles on interstate going well over 70 didn't pop out oh gesar once ! hows that grab ya ?

[phantom309]

well maybe a quencadence but I changed the pdm because I felt it was time and I druve 100 miles on interstate going well over 70 didn't pop out oh gesar once ! hows that grab ya ?

you're a hero,.