standalone harness length question

[NC_John]

I decided I am going with a Speartech standalone harness for my swap. I think I am going to mount the pcm in the cab, either under or behind the seat. How much extra length should I have added to my harness to get it there? I'm not sure where the "standard" length is set up to reach.

Thanks!

[68c10airstream]

6 years ago i installed a painless stand alone harness and paid $50.00 extra for 5 extra feet. My gm pcm sits behind the bench seat. I drilled a 1" hole on the passenger side of the firewall to hump area for the harness and ran it under the carpet and worked very well. The fuse /relay box is behind the seat also!

[mongocanfly]

I would definitely go with it mounted under or behind the seat..I used psi harness on my last swap and they have a standard 4.5ft from the passenger side head..I was told they do custom lengths but when I talked to them the other day they informed me all they do is a standard length..but did say they are coming out with a builder series harness that you build yourself..if painless does custom length i will go with them as well on my 53 ls3 build but ill run it over the top of the trans and come up under the seat..

[NC_John]

So it looks like an extra five feet will get it where it needs to be. Thank you gentlemen.

[Hart_Rod]

Originally Posted by NC_John

So it looks like an extra five feet will get it where it needs to be. Thank you gentlemen.

If you call John at Speartech, He will tell you where to measure from inorder to get the computer where you want it.

[NC_John]

Originally Posted by Hart_Rod

If you call John at Speartech, He will tell you where to measure from inorder to get the computer where you want it.

OK Rob. Thanks. I'll give John a call when I'm ready. Still waiting to finalize what connectors I need for my fuel injectors, TB, etc...

[racecougar]

Originally Posted by Hart_Rod

If you call John at Speartech, He will tell you where to measure from inorder to get the computer where you want it.

Bingo. The person putting the harness together needs to know where you're wanting to place the PCM. It isn't as simple as adding 5' to the PCM bundle. Some wires are lengthened, some are shortened, and nearly all are re-routed when redirecting the main bundle to the cab rather than the driverside inner fender. For example, when building my harness, I placed my PCM connectors 16" straight back from the top driverside bolt of the 4L60E extension housing in order to provide enough length to land the PCM under the center seat in the cab.