OK,I have a 2000 GMC 2500 4x4 LQ4 6.0l pullout I have swapped into my truck. I already had a mid 90's built 4l80e trans. The 6.0l pullout had a 4l80e trans in it also. I went through the harness and weeded out TONS. including the fuse box. I have labeled everything and have a couple questions on a couple plugs/sensors.

I have a 95 or so 4L80E trans I am using. It has 3 plugs that plug into it. The big round one which I have on the harness, and 2 other plugs. The tiss and toss plugs. On the harness I have (which is out of a 2000 GMC 2500 4x4 w/4l80e trans) I have two twisted pair of wires that go down to the trans area, a twisted Lt GRN/BLK and PPL/WHT pair that the pin out says is VSS and a twisted RED/BLK and DK BLU/WHT pair that the pin out says is also VSS but for the 6.0L only. So my question is do I need to use either of these with the 4L80E trans I have in the TISS or TOSS ?

The other question is about the Serial Data wires. I will be tuning with HP Tuners and it uses the serial port to access the computer. My truck has an ALDL plug that I an sure I will not be using. The two wires for the serial data access to the computer are DK GRN and YELLOW. Which is which? I will stop by and pick up a serial port out of a 2000 GMC truck in the next couple days and hopefully when I clip the wires behind it the DK GRN and Yellow wires will be the same so I know where they go on my harness. Just seeing if anyone has gone through this and already knows.

Thanks a ton.
Will

 

What year is your truck? you only use one of the two vss sensors on the side of the trans when installed in a 4x4. the other (output vss) is in the transfercase.

 

I have a 1991 GMC Syclone. The engine, computer, and harness are from a 2000 GMC 2500 4x4 that was used with a 4L80E also. My trans (4l80e) has three plugs on the side. The big round plug with several wires in it, and two small two wire plugs front and rear of the round plug. I was told it was the Trans Input Speed Sensor and the Trans Output Speed Sensor (TISS and TOSS) My trans looks just like the one below except 4x4 tail. Just wondering about the two sensors for the input and output speed on my trans.

 

They are in the same location.

 

OK, What I am saying is the 6.0l harness has the round plug (I know where it goes )and two other double wire plugs. purple/green pair and a red/yellow pair. I need to know where they go? do they plug into the two plugs on the side of my 4l80e? if so which one where? Sorry for all the questions on this, I have been working on this truck all winter and am finally down to about 2-3 electrical plugs before I get to start it up and start tuning

Thanks
Will