Trans wiring help... Experts/Techs nneded...

[_Syclone_]

I have transplanted a LQ4 6.0 liter out of a 2000 GMC 2500 4x4 into my 1991 GMC Syclone. I have the original wiring harness and computer hooked up. I am using HP Tuners for tuning also. The Engine is hooked up to my 1995-1996 built 4L80E trans. I am not using the original 4L80E trans the engine came with in this build. I do not have it. Anyway, I thought I had everything hooke dup correct but the trans is in 2nd gear and will not shift while driving. I guess it is in default mode. I have checked all the wiring from the main connector and the two little ones at the trans and they are all fine. I am missing something little I am sure but can not figure it out. I see in the pin out that there are like 4 other wires at the ECM that are not being used. Labeled like PRND A Input, PRND P Input, TCC Brake switch, PRND B Input. Anyway, I was thinking the 2000 truck it came out of must have another sensor elsewhere I do not have or something like that.

Any ideas?

It will go right into Reverse and drive without a problem. Just will not change gears while driving, stays in 2nd.

Thanks
Will

[RedHeartbeat]

I always have to ask this question... are you sure the tune you have is for an 80e transmission? A 60e tune will not work. If the the harness is a 60e harness, yes it will hook up but the wiring is wrong. Do you have two speedometer type hookups connected on the transmission?

[98 4X4 burban]

I have transplanted a LQ4 6.0 liter out of a 2000 GMC 2500 4x4 into my 1991 GMC Syclone. I have the original wiring harness and computer hooked up. I am using HP Tuners for tuning also. The Engine is hooked up to my 1995-1996 built 4L80E trans. I am not using the original 4L80E trans the engine came with in this build. I do not have it. Anyway, I thought I had everything hooke dup correct but the trans is in 2nd gear and will not shift while driving. I guess it is in default mode. I have checked all the wiring from the main connector and the two little ones at the trans and they are all fine. I am missing something little I am sure but can not figure it out. I see in the pin out that there are like 4 other wires at the ECM that are not being used. Labeled like PRND A Input, PRND P Input, TCC Brake switch, PRND B Input. Anyway, I was thinking the 2000 truck it came out of must have another sensor elsewhere I do not have or something like that.

Any ideas?

It will go right into Reverse and drive without a problem. Just will not change gears while driving, stays in 2nd.

Thanks
Will

do you still have the original wiring harness for the engine and tranny thet came in your truck?
if so you will need to compare the plugs for the tranny. i was having a simular problem.

i had 13 wires in my factory tranny plug and only had 12 in the plug in the harness i used for my swap. i had to re pin thre tranny plug using my old harness as a guide. the colors are the same just make the new look like the old and it should work.