ECM and TCM ideas for mounting, in cab or under hood

[flipper58]

I am at the stage of running and mounting my wiring for the ECM and the TCM for the LS3/4L60E connect and cruise. I am leaning toward mounting everything inside the cab, even with the Vintage Air unit taking up precious under dash space. I've searched and found some threads on this, but there never seems to be enough info. I would really appreciate some pics and ideas on routing the wiring and mounting.
Thanks,
Phil

[68c10airstream]

My painless harness with an extra 5 feet of cord put the pcm behind the drivers seat. Cut the required 1" hole forward of my low floor hump, on the passenger corner up the firewall a bit. Brought the round harness inside cab and immediately laid it flat on top of a roofing product called ice and water guard, Sticky side down, laid wires on top of it, and put one more layer of ice and water guard on top, sticky side down. I did this on the side of the low hump so i didn't have carpet that looked like an anaconda was resting underneath it. Some have commented concerns about wires getting damaged, but the wires are in the middle of a sticky sandwich. Wires don't move, laid low, and protected.

[mongocanfly]

68c10....how do you like the painless harness? any issues with it?

[darrellyates]

I put mine in the cab, on the firewall. I would say plenty of space, but not really. Everything fits, including vintage air. I do have to section and shorten the ash tray, as it hits the connectors on top of the ECM. Other than that, and having very little room for the various hoses for the heat and a/c, everything fits. Will try to post a couple of pix of the mounts and set up. Sometimes my pix files are large and don't load.

[flipper58]

Originally Posted by 68c10airstream

My painless harness with an extra 5 feet of cord put the pcm behind the drivers seat. Cut the required 1" hole forward of my low floor hump, on the passenger corner up the firewall a bit. Brought the round harness inside cab and immediately laid it flat on top of a roofing product called ice and water guard, Sticky side down, laid wires on top of it, and put one more layer of ice and water guard on top, sticky side down. I did this on the side of the low hump so i didn't have carpet that looked like an anaconda was resting underneath it. Some have commented concerns about wires getting damaged, but the wires are in the middle of a sticky sandwich. Wires don't move, laid low, and protected.

Thanks much. I have American Autowire kit so I think I have some flexibility to do something like that.

[flipper58]

Originally Posted by darrellyates

I put mine in the cab, on the firewall. I would say plenty of space, but not really. Everything fits, including vintage air. I do have to section and shorten the ash tray, as it hits the connectors on top of the ECM. Other than that, and having very little room for the various hoses for the heat and a/c, everything fits. Will try to post a couple of pix of the mounts and set up. Sometimes my pix files are large and don't load.

Thanks. Very helpful.
Phil

[68c10airstream]

My painless wire harness has been perfect. Easy hook up with 2 ground eyelets, 1 12+ hook up constant, 1 12+ hot with key on/start. Came with a very good quality fuse panel populated with relays and fuses as needed. All plugins were tag flagged with id, and have a clear flexible covering over the flag. No circuits left out.

[mongocanfly]

thanks 68..did yours come with wire loom ?..I noticed their pic doesn't show it and they sell a loom kit seperate....but its pricey..I used psi on my last swap...very good quality but they don't offer a extended harness..

[darrellyates]

Originally Posted by mongocanfly

thanks 68..did yours come with wire loom ?..I noticed their pic doesn't show it and they sell a loom kit seperate....but its pricey..I used psi on my last swap...very good quality but they don't offer a extended harness..

I don't know where you are in Alabama.... However, I used American Autowire for the body harness. Interior, underhood, lights, everything. I got the engine harness from RCI just outside of Huntsville. Ricky is super sharp on everything LS. Got the computers from him as well as engine and trans. Truly plug and play, and several thousand less than GM's set up. LS3, 4L60E, everything. If you're close enough, give him a call. His harness comes completely in wire loom, and had easy to follow instructions. Even I could install it. That's the fuse block for the LS harness you see in the glovebox door.

Thanks!

[mongocanfly]

thanks Darrell. .yeah I'm only about 20 miles from him....and I've talked to him before...he advertises on craigslist alot....
I've got 2 LS swaps coming up..my last one I used the psi harness and its great....but I was limited on where I could put the ecm...basically underhood or behind dash...I opted for behind dash...big mistake...with the factory ac and heat box there's just no room...I managed to get it behind the glovebox but it wasn't purty...I said never again...from now on I want them under or behind the seat...but the psi isn't long enough to reach...I've got a buddy using aaw on a station wagon he's building...looks like quality stuff...

[Steve Cole]

Try BP-Automotive.com

His harnesses are 5 feet long from the back of the intake. He will also make custom length harnesses as well.

[scoot_mcgrute]

I mounted my computer down by the radiator on my 66 using an S10 computer mount bracket. I used a stock truck harness and had my buddy re-route it to fit the car intake better and the ecu wanted to live where it ended up. Haven't had any problems at all with it down there and what I like most about it is your eyes aren't drawn to it when you pop the hood, I didn't want it sitting on the inner fender like it does on the Silverados and running it inside the cab seemed like a lot of unnecessary work for the direction I went.