trans question- started acting up

[jasonroman]

so this morning i am going to work. start truck. notice abs light on. i did see this on yesterday when i started the truck. after 1-2 minutes. the light went off. so i thought nothing of it.

this morning, start truck see light. head off to work. same- light went off a few minutes into drive. but something seemed weird. almost felt like the trans was not shifting as normal.
i stop and started several times- looking to feel trans shifting, but didn't seem to be acting correctly.

leaving work.

start truck- see abs light. pull out of my spot and usually from where i park to the stop sign, i can alway feel truck shift. no shift.

i make a right onto the main road- screaming- as if to be stuck in first -
couple hundred feet. i notice everything on dash- GOES DEAD- rpm- speed- every needle dropped to 0

then seemed to correct itself and from there to the house. truck seemed to shift fine.

i believe yesterday on the drive to work. i did notice the same dash play- momentarily, everything goes to 0
and then truck is fine????


any ideas?? and if i am posting in the wrong place. please let me know and i will move.

truck is a 97 tahoe- 4 door- 4x4- 96k

[AussieinNC]

Originally Posted by jasonroman

so this morning i am going to work. start truck. notice abs light on. i did see this on yesterday when i started the truck. after 1-2 minutes. the light went off. so i thought nothing of it.

this morning, start truck see light. head off to work. same- light went off a few minutes into drive. but something seemed weird. almost felt like the trans was not shifting as normal.
i stop and started several times- looking to feel trans shifting, but didn't seem to be acting correctly.

leaving work.

start truck- see abs light. pull out of my spot and usually from where i park to the stop sign, i can alway feel truck shift. no shift.

i make a right onto the main road- screaming- as if to be stuck in first -
couple hundred feet. i notice everything on dash- GOES DEAD- rpm- speed- every needle dropped to 0

then seemed to correct itself and from there to the house. truck seemed to shift fine.

i believe yesterday on the drive to work. i did notice the same dash play- momentarily, everything goes to 0
and then truck is fine????


any ideas?? and if i am posting in the wrong place. please let me know and i will move.

truck is a 97 tahoe- 4 door- 4x4- 96k

Your in the right place...

Sounds like a ground wire issue...

Under the drivers door on the chassis near the cab support you will find 2 ground cable connectors...remove them and clean both the connector and the chassis itself....get them shiny and new like then reassemble....

Then check all the other ground wires you can find,,,,especially the engine to chassis and chassis to cab wires...

Then check the trans shift computer connections...its usually right next to the ECM and is approx 4" x 5"...

Let us know how you go

[Captainfab]

On the '96+ OBD II the trans is controlled by the PCM (Powertrain Control Module), a single unit.

[AussieinNC]

Originally Posted by Captainfab

On the '96+ OBD II the trans is controlled by the PCM (Powertrain Control Module), a single unit.

Good catch Captain...I didnt realize OP had listed vehicle as a 97...grounds still matter whatever year it is...

[jasonroman]

Originally Posted by AussieinNC

Your in the right place...

Sounds like a ground wire issue...

Under the drivers door on the chassis near the cab support you will find 2 ground cable connectors...remove them and clean both the connector and the chassis itself....get them shiny and new like then reassemble....

Then check all the other ground wires you can find,,,,especially the engine to chassis and chassis to cab wires...

Then check the trans shift computer connections...its usually right next to the ECM and is approx 4" x 5"...

Let us know how you go

thanks for reply.
looked under truck on driver side. did not see what you are talking about.
nor do i know where all the grounds to look for are.
or where the ECM is.

not a mechanic. just a guy spending the money i had to spare on a bathroom remodel- NOW HAVING TRANS ISSUES.


watched it again yesterday- not all gauges- just the tach and speedo go dead. left in the morning and seemed to not shift out of first. until gauges go dead. and i pedal it. not sure if it then takes 2nd or what but make it to work driving 40-50 mph and the truck revving around 3k.

left work. did small circle in parking lot. watched gauge die - pulled out and drove home as if nothing ever happened.....

reached home- had to run and get cash - went from stuck in first- to NOTHING- where i give gas and all that happens is engine revving- then eventually brake light goes off after gauges die and truck runs ok again???

at a loss.

[burnin oil]

Had a grand am with a similar issue. You would be driving and all of a sudden the gauges would go dead, then all the dash lights came on and the needles would peg. Car would run great for awhile afterwards. It was the ignition switch.

[Bigdav160]

The trans won't shift without a VSS signal. You need to check the trouble codes

[AussieinNC]

Intermittent electrical issues can be difficult to track down...

Start by checking each and every plug under the hood is fully attached....

Check the Ign switch wiring at bottom of column for a loose plug

There seems to be a common issue, that being power loss to the truck...then almost immediate return...sounds just like a loose plug somewhere in the system...

Check the plugs on the ECM...a square metal box under the hood with two or more thick wire looms..these sometimes get corrosion under the plugs due to condensation...

You can google the ground locations on your truck....