96 tahoe transmission issues

[reverend jim]

My money is on the ignition switch and here's why.

If I jimmy the switch around and get the gear indicator light to come on full-strength the thing runs like a top. But try to start/run it when the indicator is weak or gone and the thing will either slam gears or just go into 2nd gear "safe mode" right off the bat. Sometimes if the switch is in the first position for long enough the light will slowly flicker to life, and if you drive it for a little while and stop, it does not want to come to life again for quite a while.
It is back in the shop as of tonight and should have a new switch and, hopefully, be up and running by Thursday night.

Thanks for the thoughts!

[j cAT]

[quote=reverend jim]My money is on the ignition switch and here's why.

how many miles on this vehicle ? most likely the pigtail that shorted out at transmission damaged ignition switch contacts .

[MT-2500]

Reverend jim
Ign switch is a good thing to check and also wiring and also wiring as J Cat metioned.
There should be a gear selector switch on the side of transmission.
Check it and the wiring to it.

Also some 96 transmissions had a computer wiring/ground problem.
On some they came out with a wiring harness kit to correct the problem there. I can not find the info on it but.
For more details on it go to the link I posted in the PM I sent.
Good luck MT

[reverend jim]

OK!.... here's the last post (hopefully), it's a Big-Un' !

The problem was directly AND indirectly attached to the ignition switch...not the tumblers (or "key switch") but the electric switch at the base of the steering column. Apparently there is a GM TSB which discusses this which was eventually found by my diligent tranny guy after hours of beating his head against the Tahoe. I will post the TSB # when I get it.

Basically, the '96 was the object of a change in the ignition switch system which replaced the two-piece setup of a switch and a relay to a one-piece unit which encompases both. Apparently, up to this point, the answer was to replace one or the other but it was discovered that just replacing the switch and not the relay, or vice-versa, would burn out the older of the units in just a few months... so GM replaced it with a one-piece unit and put out this TSB to inform everyone, that cared to search for hours and hours to find it, that this was the fix.

The best part is that this repair had already been done at some point in the Tahoe's life (by who-knows what mechanic) but VERY poorly. Additionally, the truck was also equipped (presumably by the same person judging by the electrical terminations and zip-ties) with one of those used-car-lot key-card locks under the dash.

Apparently, the shoddy work and addition of this key card had slowly-but-surely shorted out and severely heated up the main harness plug on the steering column and made it so brittle that, upon removal for inspection, it crumbled like an old cookie...

...still with me?...

...SO... a trip to the salvage (junk) yard produced a nice clean harness plug. The key-card setup was removed and any and all extra wiring and crimp connectors were deleted. And, finally, a new GM switch-relay combo was installed. All this was done with nice solder joints, clean looms, and care not to be a bull-in-a-china-shop.

The grand result is that I now have 600 miles on the Tahoe with absolutely no problems. It has been on long day trips, stop and go stuff, fun in the snow, and all without a hiccup.

So thanks to all of you who threw possibilities at this quandry. All of them were helpful in one way or another. And thanks, especially, to Spath Transmission in Chico, CA who was instrumental in me NOT pushing the Tahoe off lookout point.

This info would probably be helpful here as an Ignition System post also, but I'm not sure of the best way to do so. Thanks - Jim

[alexmac]

i've replaced many ignition switches for this problem. the switch isn't putting enough voltage to ignition 2(white wire at switch usually), can also be
checked by putting test light on trans fuse at ipc& turing on ignition any
commanding transmission solenoids with scan tool. also a remote start can cause trans to default with it isn't powering this circuit.

[MT-2500]

Reverend jim
You are welcome And
Thanks for posting back how it went and letting us know how it went.
Glad all is well and you have got it fixed.
MT

[Jeremy-WI]

Originally Posted by alexmac

i've replaced many ignition switches for this problem. the switch isn't putting enough voltage to ignition 2(white wire at switch usually), can also be
checked by putting test light on trans fuse at ipc& turing on ignition any
commanding transmission solenoids with scan tool. also a remote start can cause trans to default with it isn't powering this circuit.

On the 96 the switch messes up the trans fuse circuit, remote starters that are improperly installed can bring the same problem.

That tranny guy sure did some homework, the last I knew that TSB was for 97 and newer pickups.