View Full Version : 4L80E harness with 4L60E trans?


flynbrian48
03-30-2010, 08:58 AM
My swap is an '01 6.0 from a 2500 HD 4x4, with a 4l60E from an '05 van, into a '48 Diamond T pickup. I'm using the donor truck harness as a stand alone, with help from this board, the LT1swap site, and a buddy here who provided the GM factory schematics (I actually have TOO much information!). I have the ECM from the donor truck, and most of the harness.

What I don't have is info about the pin out for the trans plug. I have searched here and found pin outs and the pins to swap for the 4L60 to 4L80, but I'm going the other way. The trans plug physically plugs into the trans, but I know the 4L60 uses one speed sensor, and there is a white wire in it's pin connector the 4l80 does not use (according to the 4l60 to 4l80 swap pin connector I printed). I want to have the wiring completed before the engine/trans are installed, as it's much easier to access everything while the engine/trans are on the shop floor than in the truck.

I know it sound simple, but I want to make sure I have this figured out properly. Any help?

Brian

slow67
03-30-2010, 10:24 AM
My swap is an '01 6.0 from a 2500 HD 4x4, with a 4l60E from an '05 van, into a '48 Diamond T pickup. I'm using the donor truck harness as a stand alone, with help from this board, the LT1swap site, and a buddy here who provided the GM factory schematics (I actually have TOO much information!). I have the ECM from the donor truck, and most of the harness.

What I don't have is info about the pin out for the trans plug. I have searched here and found pin outs and the pins to swap for the 4L60 to 4L80, but I'm going the other way. The trans plug physically plugs into the trans, but I know the 4L60 uses one speed sensor, and there is a white wire in it's pin connector the 4l80 does not use (according to the 4l60 to 4l80 swap pin connector I printed). I want to have the wiring completed before the engine/trans are installed, as it's much easier to access everything while the engine/trans are on the shop floor than in the truck.

I know it sound simple, but I want to make sure I have this figured out properly. Any help?

Brian

Yes you can. You might be able to use the wires/pins from the ISS to add the additional wires back into the main trans connector (since the 60E doesn't use an ISS).

flynbrian48
03-30-2010, 10:38 AM
I guess I'm sure I can, but my question is, "how?". There's a white wire, which my 4L80 plug/harness does NOT have, in the "S" position in a 4L60 plug, which goes where? To what pin in the ECM does this go, and can I simply add it? Or is there a wire in the 4L80 plug I simply need to move, as in going from 4L60 to 4L80, which a brown wire I understand gets swapped into the position the missing white wire goes, that I can switch?

Brian

slow67
03-30-2010, 11:15 AM
I guess I'm sure I can, but my question is, "how?". There's a white wire, which my 4L80 plug/harness does NOT have, in the "S" position in a 4L60 plug, which goes where? To what pin in the ECM does this go, and can I simply add it? Or is there a wire in the 4L80 plug I simply need to move, as in going from 4L60 to 4L80, which a brown wire I understand gets swapped into the position the missing white wire goes, that I can switch?

Brian

On the trans harness: Move pin "S" to "U"

Add wires: Pin C1 (blue connector) 78 to Pin "S" on trans connector.
Pin C2 (red connector) 42 to pin "T" on trans connector.

You will need to have the PCM reprogrammed for 4L80.

flynbrian48
03-30-2010, 12:35 PM
You mean have the PCM reprogrammed for 4L60, since it's orginally programmed to operate the 4wd 4L80? I'm not meaning to sound dense, but I'm going FROM a 4L80 to a 4L60. ( I have the pin out to go from 4l60 to 4l80, which is not what I'm doing ) The VSS connecter, I'm assuming it was the rear one, in the harness (4l80) plugs into the 4L60 VSS sensor at the tailshaft, leaving the forward one unconnected?

slow67
03-30-2010, 01:41 PM
You mean have the PCM reprogrammed for 4L60, since it's orginally programmed to operate the 4wd 4L80? I'm not meaning to sound dense, but I'm going FROM a 4L80 to a 4L60. ( I have the pin out to go from 4l60 to 4l80, which is not what I'm doing ) The VSS connecter, I'm assuming it was the rear one, in the harness (4l80) plugs into the 4L60 VSS sensor at the tailshaft, leaving the forward one unconnected?

Yes, you have to get the PCM reprogrammed to a 60E from an 80E and vice-versa. Whoever re-programs it also needs to know if it will be 2wd or 4wd with the 60E.

The pinouts above I gave are correct when going to a 60E from an 80E (if I said otherwise, that was a typo).

Pins C2 (red) 20 and 21 are for the Speedo (VSS). The wires in 22 and 23 are for the 80E ISS. You might be able to re-use these, and use those wires for the 2 wires you need to add above (I am unsure if the pins are the same between the ISS and trans connectors).

flynbrian48
03-30-2010, 04:04 PM
Thanks, that helps! Good idea using the no longer needed ISS leads repositioned for the 4L60 "missing" wires...

Brian

slow67
03-30-2010, 07:21 PM
Thanks, that helps! Good idea using the no longer needed ISS leads repositioned for the 4L60 "missing" wires...

Brian

Yeah I know the pins in the PCM will (obviously) work, but I don't know for sure if they work in the trans connector. If not, you can buy the pins individually (less than $1 a piece).

Agent_Orange_Shuvel
08-21-2012, 11:11 AM
On the trans harness: Move pin "S" to "U"

Add wires: Pin C1 (blue connector) 78 to Pin "S" on trans connector.
Pin C2 (red connector) 42 to pin "T" on trans connector.

You will need to have the PCM reprogrammed for 4L80.

Not trying to revive a dead thread but figured I would make a correction for anyone referencing this thread as I did.

Pin S on the trans connector goes to C1(blue connector) Pin 79 not 78 as stated above.