iansane

iTrader: (1)

So I made a boo boo. I have the wiring harness spliced together, loomed and ran through the factory location down through the fender and into the passanger side foot well to mount the ecm in the stock location. I'm finishing up the fuse block over above the heater box and realize the truck harness I used isn't set up for electric fans. I have the block already wired for the 3 relay setup used in cars and have my stock duals fans wired up but no ecm control for it... What have you truck harness guys done for fan wiring? The ecm is a blue/red that I've wired mostly like an '03. Any help would be appreciated.

I seached for fan wiring, truck fan, lm7 lq4 lq9 fan wiring and got nothing...

screeminchicken

iTrader: (2)

I am no expert but if your PCM does not have provisions for tripping the fan relay.....I would think u could use a temp sensor to trip the relay just like in late third gens.

If u have dual fans and want the 2nd to come on with the ac, I am not sure, but somehow use the A/C line preasure switch or A/C req signal wire to trip relays for the 2nd fan.

Again , I have never done it, others may chime in

Good luck

iansane

iTrader: (1)

I'd be surprised if the pcm is incapable of triping the relay sets for the fans. If I went with a temp sensor, I'd either (a) need to find one in the funky 12x1.5 (?) pattern that is the LS1 cylinder head or drill out the head for a standard one for a small block. However, than would only switch one fan. And I have no A/C. It's a vert, I just put the top down.

Appreaciate the suggestions.

Pocket

iTrader: (24)

Fan relays are super simple

Im not sure if you're using stock relays or truck stuff
Heres how i use 3rd gen fan relays with the newer PCM
I used two off of JY V6 cars, most of the wiring lengths are correct for mounting near the booster and retaining PCM operation



I later dropped these and went with a Cadillac fuseblock as it had two mini relays and 12 mini fuses. Enough to run my single fan, fuel pump and fuse all of my engine electronics

iansane

iTrader: (1)

They relays aren't the issue I was having. Like I said, I have the fuseblock wired up and ready for signal input, just needed to know from where the pcm activated it. Figured it out, BTW. Talked to my tuner who activated fan control in the pcm and it comes from the same pins as an fbody.

Pocket

iTrader: (24)

The pins were listed above on the diagram