1997 Tahoe 4wd model

[skivvywaver48]

I have a Tahoe which I keep for a backup vehicle and went out the other day to drive it. Got on the highway and right off the bat, I noticed the speedometer registered 0. Then the transmission wouldn't shift from 1 to 2, etc.. drove it for a few miles and it didn't clear up so I headed back to the house. Had a friend come over today with his scanner (pro model scanner) and the only code that showed up was nothing associated with the tranny or drive train. Don't remember the code and it was erased. Both of us think it may be associated with the TCM but I wanted to post up this thread to see if anyone else has had this issue and if so, what fixed it. Any help will be greatly appreciated as I don't want to sink a lot of money into the suv but would love to keep it in case my truck craps out. So guys, what say you?

Mike from NorthCacklacky

 

[Fless]

@NickTransmissions or anyone else, any comments or questions to try to pin this down?

 

[NickTransmissions]

I have a Tahoe which I keep for a backup vehicle and went out the other day to drive it. Got on the highway and right off the bat, I noticed the speedometer registered 0. Then the transmission wouldn't shift from 1 to 2, etc.. drove it for a few miles and it didn't clear up so I headed back to the house. Had a friend come over today with his scanner (pro model scanner) and the only code that showed up was nothing associated with the tranny or drive train. Don't remember the code and it was erased. Both of us think it may be associated with the TCM but I wanted to post up this thread to see if anyone else has had this issue and if so, what fixed it. Any help will be greatly appreciated as I don't want to sink a lot of money into the suv but would love to keep it in case my truck craps out. So guys, what say you?

Mike from NorthCacklacky

No upshift from first is usually caused by an interruption of the voltage signal from the vehicle speed sensor (yours is in the transfer case) and the pcm.

First ensure it's plugged in. If it is, check the wires for damage/shorts. If the wire is fine, go to the junkard and find another OEM VSS from a 96-97 truck or suv that is intact/undamaged and swap it to see if anything changes.

 

[Eman85]

Big clue is the speedo not working. Pro scan tool should have the ability to read vehicle speed while driving. Did the friend drive the vehicle and monitor vehicle speed on the scan tool? If it didn't show any speed I would look at the Vehicle speed sensor. Take quick look and unplug the wires, common to see the sensor leak fluid into the connector. Pro scan tool should have been able to energize shift solenoids to test them.