Help needed for wiring harness on LS3 swap

[Trevor @ Tx Speed]

The GMPP harness and ECM aren't junk by any means, but the harness will require quite a bit of work to make it look good. GM builds the harness with a LOT of extra length on all of the sensors, so you'll spend days trimming it to look right. Both PSI and Speartech could set you up if you want to go with a custom harness. A custom harness would be something to consider if you're looking to run an electronically-controlled automatic trans. The GMPP kit isn't setup to control a transmission, so you'd have to buy an expensive stand-alone controller for it. That's where a custom harness and ECM can save you some money.

Trevor
Texas Speed & Performance

[Vega$69]

Originally Posted by Trevor @ Tx Speed

The GMPP harness and ECM aren't junk by any means, but the harness will require quite a bit of work to make it look good. GM builds the harness with a LOT of extra length on all of the sensors, so you'll spend days trimming it to look right. Both PSI and Speartech could set you up if you want to go with a custom harness. A custom harness would be something to consider if you're looking to run an electronically-controlled automatic trans. The GMPP kit isn't setup to control a transmission, so you'd have to buy an expensive stand-alone controller for it. That's where a custom harness and ECM can save you some money.

Trevor
Texas Speed & Performance

The OP has a 5 speed Tremec. No reason to spend a dime on a custom harness.

The long GMPP sensor wires can easily be shortened by pulling of the split wrap folding the wires to desired length and wrapping with nylon braid. You can do them all in an hour most.

Then it's just a matter of strategically placing the ECM and fuse box and tucking the excess cable into the pass side inner fender.

Can all be done in a day including beer breaks.

[Vince@Meanstreets]

BTW, where is the OP? wondering what direction he went.

[Ron in SoCal]

I have a brand new PSI LS3 / T56 magnum harness on the shelf if you need it.

[Vince@Meanstreets]

Originally Posted by Ron in SoCal

I have a brand new PSI LS3 / T56 magnum harness on the shelf if you need it.

I didn't see that on your web site Ron?

Whats my dealer price?

[Trevor @ Tx Speed]

I agree that it will work. But, the number one complaint we get from customers with the GMPP harness is the extra length that requires trimming to make it look good. Most of our customers don't want to trim their new harness and/or don't trust themselves to do it. We had a customer order a custom harness last week that returned his GMPP harness. To each his own.

Originally Posted by Vega$69

The OP has a 5 speed Tremec. No reason to spend a dime on a custom harness.

The long GMPP sensor wires can easily be shortened by pulling of the split wrap folding the wires to desired length and wrapping with nylon braid. You can do them all in an hour most.

Then it's just a matter of strategically placing the ECM and fuse box and tucking the excess cable into the pass side inner fender.

Can all be done in a day including beer breaks.

[Vega$69]

You don't need to shorten, cut or re pin to do the job.

This is my new build in progress. The fuse box is mounted behind the pass headlight and all wire bundles are securely tucked in the inner fender along with the AC and heater hoses.

The sensor wires will be folded into power braid to the proper length

[droptop 63]

Originally Posted by Vega$69

You don't need to shorten, cut or re pin to do the job.

This is my new build in progress. The fuse box is mounted behind the pass headlight and all wire bundles are securely tucked in the inner fender along with the AC and heater hoses.

The sensor wires will be folded into power braid to the proper length

Beautiful detail. My problem is space under the dash on a 63 nova once you try to make the Vintage Air box fit in the same space on the firewall. Any suggestions??

[randy]

Originally Posted by Vega$69

You don't need to shorten, cut or re pin to do the job.

This is my new build in progress. The fuse box is mounted behind the pass headlight and all wire bundles are securely tucked in the inner fender along with the AC and heater hoses.

The sensor wires will be folded into power braid to the proper length

my harness is complete and i second this. Hardest part is finding room to mount the fuse box and ecm

[Revved]

Getting ready to start my first LS376/4L65E / Detroit Speed Swap into an 80 Trans am... I've got the whole GMPP Package and I'm looking at those miles of wires and getting my solder and shrink wrap ready!!