4L60E Trans only shifts 2 and 3
 

I put this power train in my 68 c10 from a 99 camaro. Everything is working great except the auto shifting. The power train was not taken apart except to change the trans fluid and filter. It only runs in R, 2nd and 3rd. What could be the problem?

Re: 4L60E Trans only shifts 2 and 3
 

It's in limp mode, many things can cause this. A lot of times in a swap its because the transmission doesn't have power, have you checked that? Have you scanned for any codes?

Re: 4L60E Trans only shifts 2 and 3
 

Let us know the following:

What engine?
What computer?
What engine / trans was in the truck before the swap?
What electrical harness did you use?
How many direct grounds are in place between the trans and the chassis and
engine and chassis?

The info you provide will then guide us down the diagnosis / repair process for you...

:chevy::chevy::chevy:

Re: 4L60E Trans only shifts 2 and 3
 

I am having the computer person check next week. When I installed the engine and trans I tried to ground all things.

This is out of a 1999 camero 4L60E 5.7 engine. I kept all the wiring and computer. Moved the computer to under the dash. This was a basic truck with no options but in original condition. I added PS, PB, AC, Instruments, Springs, Radio, Moved gas tank Sway Bars etc.

Before the change it was a 6 cyl. with 3 speed

Re: 4L60E Trans only shifts 2 and 3
 

I am having this same issue with my swap. My combo is a 5.3 4l60 from an 03 Silverado, harness and computer are from the same truck. I attached a screen shot of the codes I have.
It was all working fine then as I was driving I heard the rpms go up and it quit shifting. Fluid was 2 qts low but I have no visible leaks. I checked power at the trans and I'm only getting 10.6v. I've been told by multiple people to check the trans fuse. I don't believe I have one??
I'm in the process of tracing the pink power wire from the the trans all the way back.

Re: 4L60E Trans only shifts 2 and 3
 

I hate just throwing parts at problem but maybe just a bad VSS sensor? I had brand new 4L60E rebuilt from a local I trust and he installed a brand VSS during the rebuild process and it was bad out of the box. But in different new one and the trans worked normally.

Re: 4L60E Trans only shifts 2 and 3
 

Thats an awful lot of codes for something like one sensor to have gone bad all of a sudden. Being this is a swap, I am still leaning toward a wiring issue. Did you check for power at the big round plug on the transmission?

Re: 4L60E Trans only shifts 2 and 3
 

not sure just a question. did you connect the tcc wire from your ecm to the brake pedal to power .

Re: 4L60E Trans only shifts 2 and 3
 

I have 10.6v at the pink wire on the big round trans plug. That is what I am currently tracing back to see where my voltage drop is coming from. I do not have the tcc wire hooked up, I was told that is optional. To clarify, the tcc gets power from the brake switch? Or it goes to the brake switch and to a power source? I'm at the end of my rope on this. Ready to pull it all out and put my 350 back in. I appreciate the information.

Re: 4L60E Trans only shifts 2 and 3
 

Just in case you weren't aware, there are 2 pink wires in the trans connector, pins "E" and "N". "E" is the 12v ignition power and "N" if from the transmission fluid pressure switch and runs back to one of the PCM connectors. Be sure you're checking pin "E".

Re: 4L60E Trans only shifts 2 and 3
 

I believe I have the right pin. I checked both. One was showing less than 1 volt the other I had 10.6. I assumed the one with the higher voltage was the correct wire. I'll have to double check I'm following the pin E wire. Thanks

Re: 4L60E Trans only shifts 2 and 3
 

I started tracing the wrong wire. Pin E is the wire I had less than a volt on. So that's a problem...

Re: 4L60E Trans only shifts 2 and 3
 

That’s probably a good thing, because it’s easier to troubleshoot. No voltage on pin E will cause a bunch of trans codes. You just need to get fused ignition power there and it should be a lot better.

Re: 4L60E Trans only shifts 2 and 3
 

This maybe a stupid question but how do I do that? And is the 10.6v on pin N ok?

Re: 4L60E Trans only shifts 2 and 3
 

Your harness should have a fuse just for the transmission (it would have originally went to the fuse block in the truck that the harness came in). But, if you don't, then you'll have to trace the wire from pin E to determine where it's going now.


Pin N is an output from the transmission fluid pressure switch and would just be grounded when active. 10.6 V sounds reasonable to see since the PCM most likely has a pull up resistor to force the signal high when the switch inside the trans isn't closed. While I can't 100% confirm it's OK, I wouldn't worry about it at this point. The missing power on pin E would cause all the trans codes that you're getting.

Re: 4L60E Trans only shifts 2 and 3
 

the tcc wire gets power from the brake switch. The brake switch is a special two terminal switch. Four single wires. The first two are for brake lights so you have constant power to the brake switch so when you apply the brakes the power goes to the brake lights, Tcc wire are on the top of the switch. It works just the opposite. Power is suplied all the time from a constant power source to the tcc wire. When you apply the brakes it disconnects the power to the trans convertor.

Re: 4L60E Trans only shifts 2 and 3
 

[quote=dayj1;8813771]Your harness should have a fuse just for the transmission (it would have originally went to the fuse block in the truck that the harness came in). But, if you don't, then you'll have to trace the wire from pin E to determine where it's going now.

I don't have a trans fuse now. So I'll have to keep tracing, but I'm assuming it goes to the pcm? My fuse block has a bunch of pink wires on one side which I assume are the injectors and one pink wire going to the ignition relay.




I will get that wire hooked up along with tracing this pink wire out and trying to figure out how to put a fuse in. Thanks for the help guys.

Re: 4L60E Trans only shifts 2 and 3
 

You may not have a dedicated trans fuse, its probably tied into another circuit since a lot of stand alone harnesses consolidate wires to make the fuse box smaller. It wont go to the PCM, it is likely one of those pink wires in your fuse block. If you have a meter you can do a continuity test between the trans plug and the fuses at the fuse block to figure out which wire it is. If it was shifting before then that means it definitely was hooked up before, and something has happened. Have you checked all the fuses in the fuse box to make sure they are all good?

Re: 4L60E Trans only shifts 2 and 3
 

Yes all my fuses are good

Re: 4L60E Trans only shifts 2 and 3
 

If you have 10v on the power wire for the trans then that should be enough since it will go up when the wngine is running. Is this an original harness or aftermarket?

Re: 4L60E Trans only shifts 2 and 3
 

It is original. That depends on which pin is the right pin. On pin E I have less than a volt. Pin N I have 10.6 v. Dayj is saying pin E is the correct pin, in which case there's less than a volt there. Should I try to check it with the engine running and see how many volts are there?

Re: 4L60E Trans only shifts 2 and 3
 

Yes, pin E should have 12v with the key on. You did have the key on, right? Who modded the harness? Have you done a continuity test between the pin E on the trans plug and the fuses in the fuse box?

Re: 4L60E Trans only shifts 2 and 3
 

Ok key on pin E has less than a volt. I haven't had time to work on it but I'm off for 2 weeks starting Monday so I hope to make some headway on it. I had my harness done i think back in 2016 by a guy named Kenny cash, I'm pretty sure was his name. He came highly recommended on the 67-72 truck Facebook page.

Re: 4L60E Trans only shifts 2 and 3
 

I did the continuity test on pin E. It goes to the sensors fuse on the engine fuse block(10A)

Re: 4L60E Trans only shifts 2 and 3
 

OK, so now we're getting somewhere. Do you have 12v on both sides of that fuse? I would think you wouldn't since you did a continuity test on the wire. If you do have power there, then you almost have to have a break in that wire somewhere between the fuse and the trans plug. It's possible that by moving the wires around to test them, it's making contact again however. Have you tried to drive it again? If the short is intermittent, then your best bet is going to be to replace the wire from the fuse to the trans plug since finding the short in the harness with it in the truck will be pretty difficult.