Hi all,

Looks like the tranny is on it'* last leg. While in OD, I can sometimes feel it quickly downshift, return,downshift, return, downshift, return and resume.

Put some Lucas trans fix and it feels like it "fixed" the problem.

So it looks like I need a new transmission.

I want to pick up a transmission core, rebuild it, and swap to minimize down time. I understand that the 4t60e has a few variants. How do I find out what I have and which one I need?

Thanks

You may not have a bad trans. The torque converter on these transmissions is controlled by the PCM. If something is wrong with the engine ie, long over due tune up, a bad TPS sensor or a very cold transmission and the PCM will unlock the torque converter. Either to prevent damage, or to help warm up the transmission. So we could start with simple diagnostics to maybe find out why its doing that.

Your right, there are a few variants of the 4T60-E trans. Only difference'* are really, is with the final drive ratio. Try to find one close to your year and model and you should be fine. Only way to identify the trans is by a metal tag on the trans. Only thing you really have to compare is what'* in this picture.

thanks Mike,

Of course diagnosing a cheaper easier problem is my preference.

Where do you want to begin?

I will tell you that downshift, return,downshift, return, downshift, return happens very fast (almost like someone kicked the car), and usually on a uphill. It started at low RPM around 50-55mph but progressed to happen from 60-65mph


I also noticed that the wiring connectors are different on the 4t60e

Correct me if I'm wrong, but looking at the diagram, it looks like if A has power on the connector, it'* a newer transmission.

Can anybody confirm?