Hey guys I would really use some help here. I have a 02 WS6 Trans Am with the 4l60e in it. This car will not shift into 3rd gear. When it goes to shift into 3rd gear the engine just revs up like its in neutral. I've had the trans rebuilt and tested on on the bench at the Chevy dealer, and the trans itself works. I'm trying to figure out where to go next. I have a Diablo tuner for the car and am trying to work with them to help me figure out if it's the tune that is messed up. Are there any wiring issue I could look at between the pcm and the trans that yall know of? I'm just trying to get the vird back on the road and drive it.
Background on the car: I bought this car from a guy who was trying to set it up drag race. He a put a small high stall torque converter in it and did nothing to help the trans stay cool. So he smoked the trans. Was also told that he had the car tuned on a chassis dyno woth that high stall torque converter in it. And I guess whatever shop he had it done at used the Diablo tuner with their dyno.
Any ideas or advice would be greatly appreciated.

 

-Original Power-Train?
-Transmission stock with aftermarket Torque-Converter?
-Fluid level?
-Fluid condition?
-Line-Pressure readings?
-Diagnostic Trouble Codes?
-Data-Stream conditions during abnormal operation?
-Line-Pressure during abnormal operation?

Can a Tune cause issues... sure.
Can a PCM cause issues... sure.
Can wiring cause issues... sure.
Does your vehicle have some kind of common flaw with the wiring between the PCM and Transmission...
But took nearly 20-Years to manifest...
No. But thanks, I had a good laugh.

 

vorteciroc has some good suggestions.

Did you put a gauge on it and see what it does when the trans shifts into 3rd?
How did the chevy dealer test the trans 'on the bench'? How do you know that it works? Do they have a transmission dyno they tested it on?
I do not know anything about tunes so can't help you there.

 

The tranny itself can't be in 'neutral' when U shift it in D no matter what tune soft do U use or electrical problems U have cause its hyd. operations tranny.
Better to claim warranty repair from rebuilder

 

A common story on here: a guy gets his 4L60e rebuilt by a local shop. 3rd gear won't engage.

The problem is often related to the 3/4 clutch pack and it fries itself.

Maybe this isn't your situation but it certainly happens frequently enough to almost be a cliche'.

 

Thank ya'll so much for all the suggestions so far I am working on checking them all off my list. Tonight I read out the wire harness from the trans to the PCM. I have one wire that is reading open. It is the Low Reference for the 5.7L engine, circuit # 407. Would that cause it not to shift into 3rd?

 

In GM/ Delphi 12v/ 5v/ 3.3v Monitoring or Control Circuits (OBD2/ GM Class 2 Data. NOT GM High Speed - Low Speed LAN/ CAN BUS)...
The "Low Reference" side of the Circuit behaves as the Negative portion of the Circuit.

So yes, an "Open" Low Reference Circuit can result in a given Component being inoperable...
The question is: "Which Component has an Open connection to the Low Reference Circuit?"

In regard to the 4L60E Transmission Family...
The two Shift-Solenoids are basic 12v On/ Off Electrical-Solenoids.
They receive 12v+ from the Ignition-Switch...
and are controlled (On/ Off) by the PCM/ TCM via an internal 12v-.

In this situation, the negative portion of the Shift-Solenoid Circuit is considered to be a Negative-Bias Control-Circuit...
and not a Low Reference Circuit.

What "P" DTCs are current and/ or history for the Transmission?
You are going to try and eliminate any correlation between the Transmission Circuits and the Open Low Reference Circuit that was found.