Mark Russell

I put an LS1/4L60e from a 2000 Camaro into my 77 C3. Engine is running nice and isnt throwint any codes. But, I have not been able to get the transmission to shift past 1st. I have Park, Reverse, N, D (But only 1st). I have limp mode if i pull the plug. Even manual shifting will not change anything. I have been looking thru threads for months now. I checked the selonoids for clicking, they responded. I have power to the transmission harness.

Checked the VSS, puts out volts when I turn the wheels, TPS is brand new and has 5V. I have not used a transmission scanner yet.

Either my harness is not doing the job or i think it could be caused by faulty grounds thru the PCM. My pressure is also high at about 210psi in park. Doesn't change as I increase RPM. Since most of the electronics in the tranny rely on a ground, it would make sense it is not grounding well enough. I can figure out how to ground it any better. I have seperate grounds running to the engine block. The block is grounded with a thick strap to the frame.

Has anyone had an issue with a bad ground really affecting shift performance?

Also, I made my own stand alone harness from the original. I thought I could save $700, but I just ordered the P/N 60508 Painless Harness.

If the harness does not change anything, I will have to bring the car to a transmission shop.

mrvedit

Its great that you have already checked a lot of things, especially removing the trans connector (plug) and line pressure.
So far, I think you just have a major electrical/harness problem. Since you have 1st gear, reverse and 3rd gear (via limp mode) the trans is likely mechanically sound.
Stuck is 1st gear could be a wiring harness pin mixup.
Also, 210psi in Park is very high, indicating that the circuit to the PCS (also called EPS) is disconnected, which then maxes the pressure. Also likely a wiring harness pin mixup.

Mark Russell

I have checked the harness numerous times and fep inner the whole thing and started over fresh. I'll check pins again while I wait for my $700 painless harness. Do you think it could be bad grounds? Most I the 4L60e relies on grounding out for pressure contr and sell nous activation I believe. My painless harness instructions mentions a lot about faulty grounds affecting the transmission.

Also, my transmission guy (very old school) thinks it's because I grounded out my NSS and the computer doesn't know what gear I'm in. I thought the NSS is just a safety switch and the pressure manifold in the trans tells the computer what gear it is in. His old school approach makes me hesitant to bring him the car. I might
Need a new transmission guy.

I'm also wIting for my cousin who has a transmission scanner to come over and see what the transmission thinks it's doing but idk when that will be.

mrvedit

Mark, you are correct about the pressure manifold switch; the NSS (Neutral Safety Switch) only affects starting the engine. Why not just run a #10 thick wire from the trans to the engine to ensure the trans is well grounded.

Mark Russell

Where do I runn the ground from on the transmission? I heard the older 4l60e could be externally grounded

mrvedit

You might find this wiring diagram useful:
http://www.msgpio.com/manuals/mshift/wiring.html

Note that it appears the pressure switch uses the case as ground. Thinking about that, it does sound like you might have a grounding problem.
Just run the ground wire to any bolt on the trans case.

Forrest Finley

I'm new to the LS forum and would love some help so I can finally drive my car after 3 years.
I have the same exact problem that you have described with with you car. Did you ever find out what it was? Was it the ground wire? I have tested every wire in my harness 3 or 4 times and I'm hunting for the right answer. I have replaced the pressure sensor plate inside the tranny, tested the the tranny harness, good, solenoid, fuses all good, any real help would be awesome.

mrvedit

Forrest: Welcome to ls1tech!

Now that you have made your first post, why not start your own thread and describe exactly what symptoms you have. Your symptoms might be a little different and that the make a huge difference in the diagnosis.

Forrest Finley

Thank you: my symptoms are as follows. I had the two pink wires swapped that go into the 4l60e tranny plug. Wire E and wire N were swapped (they are both pink, my bad)and the 10 amp fuse would blow figured that out and replaced the tranny pressure plate sensor pack. Now I have reverse and 1st. I would red line the engine no shift. Once on the gas it pulls really good but once I let off and get back on it it feels like it is slipping. Removed the fuse and it does go into limp mode P/R/N/3. I purchased the tranny out of a 1999 camaro with 98k miles, fluid was clean, no smell. Please any help would be awesome.

Forrest Finley

I know this is why there are forums, to help others with the trials and tribulations that others have gone though. I called a friend and he suggested that I hook up a scanner that has a live data feed. All were good except the VSS =0 speed. There was a bent terminal on the inside of the plug. How this happened I have no idea. Straightened out the male terminal on the plug and low and behold the $ 400 4l60e works like a champ.
I would like to say thanks to everyone for all of there information that I have read over the last 3 Years.

bbond105

Sorry I wasn’t able to post sooner, but glad you were able to figure it out.