AT doesn't shift correctly from computer
 

2002 ls6, 1999 Camero 4l60e

If I use the shifter and drop it in low, it starts fine...but when in d the tranny starts like it is in 2nd.

I thought it might be the tcc release....but this is set up correctly on the brake pedal.

I'm going to check each wire from round tranny plug to computer for high resistance. Any other thoughts?

To me it seems like computer isn't shifting it correctly.

additional information....

so when i drop the shift lever into low or 2---it doesnt shift at all, telling me its in 2nd gear.

When I count upshifts it seams like it is staying in 3rd gear.

So no 1st, no 4th= bad shift solenoid right??? Well I pulled the pan and check the resistance of the solenoids....both are exactly 22 ohms...perfect.


So if its not the solenoids, then what should I check?

Sunday, under the car covered in AT fluid bump.....any ideas?

Starts like it's in second or third? If it's third you don't have power to the transmission. The shift solenoids on a 4L60E default to third with no power with the selector in "D." You also won't get torque converter lockup or any shifting action.

Can you command the shifts electronically using something like HP Tuners? If you can, you are getting power but there may be an issue with the transmission communicating to the PCM in time for the internal checks to complete. I've actually seen this be a power issue too.

I pulled the pan to check power and shift solenoids.

The inside of the transmission and pan look like they are brand new....well, they are...I had it rebuilt in April....60 miles since then on them. No crud, no shavings, smelled good.

Since I had bought them anyway, I replaced the A and B solenoids. The old ones measured 22ohms on the bench...but what the heck.

No change at all. Road tested and I am only running in 2nd and 3rd. When I manually shift into 1st, I am really in 2nd. When I put it in "D"I do not switch from 3rd into 4th.

While under there I checked the power into and out of the solenoids. I was getting a strong 12 volts. So I am getting power to at least that part of the Tranny.

any other ideas or things to check? I do not have HP tuners. I do have a program that hooks into the OBD2. But I cant change, only look.

Is this a new swap or was this working fine and now has a problem? Sounds like limp mode to me.

I thought limp home was only 3rd gear.

But this was never working fine. I had to pull my transmission for a failed torque converter and while the trans was out I had it rebuilt with a shift kit. It had a new internal harness and a new solenoids, and new just about everything.


One thing that was recomended was to change out the neutral safety switch on the side of the trans, near the cable. Would this cause it?

so someone should have told me....there are no neutral switches on my setup. My Neutral Safety Switch is up by the shifter. thats where it is on a c4. However, mine has beeen programmed out of the ECM. My Safety Switch is not attached to anything except the lights anymore.

so, back to step 1....

1. no first or fourth using either the manual shifter or the computer in "D".
2. solenoids are ok.
3. Transmission has power to pink wire (12 volts)....should be on only with ignition, but for some reason it is on all the time.
4. VSS is giving correct speed output to computer and to dashboard.
5. rpm seems correct.
6. computer cannot see what gear it is in....when I look at the reader I have, it shows no gear whatsoever...instead of showing 1,2,3,4 R etc.
7. I have taken every single wire on transmission and checked resistance and continuity back to computer. All showed continuity and resistance less than 1 ohm.

what do I check now?

I had a weird issue a while back that sounds similar to this. I eventually found that the transmission fuse in my underhood box was bad (although it looked completely fine). If you're getting power to the trans this is unlikely the case, however, replace the fuse anyway and see what happens.

...also, my E40 controlled LS2 has an additional TCM that works with the ECM. Not sure if your setup has a separate controller that it needs to function properly....but if you need one and don't have it....that would probably cause the transmission to function in the way you are describing. Unsure, but just a thought.

No TCM in this model. The ECM controls the transmission.

Please take a meter and check the ohms between pins 6 and 14 on your OBDII plug. Still sounds like a communication problem to me. This will confirm or disprove that.

You don't need to do this. This only applies to vehicles running a high speed GM lan communication setup. Since the PCM controls your trans, this won't help you.
Who made your harness and why does the trans always have power to the pink wire? That is a good place to start.