71 Camaro ls3 swap wiring questions

[Kmart78]

I just got a GM connect and cruise ls376/480 crate engine with the GMPP computer/harness for my 71 Camaro project and have a couple questions. I'm new to this so excuse my questions if they are stupid but the GM install instructions leave a little to be desired. I'm trying to figure out the fuel pump wiring and need some help. My Aeromotive gas tank came with a relay and wiring harness yet the GM instructions say that the fuel pump lead needs to be connected to the fuel pump positive and that its fused/relayed and controlled by the computer. So, do I JUST connect the GM fuel pump wire to the positive on the pump and not use the relay and wiring that came with my gas tank? Also, same question for the cooling fans. I'm running a Dewitt's radiator with two electric fans. According to the GM instructions, I can just connect their fan control wire directly to the fan since its fused/relayed but since I have two fans, can I just connect their wire to BOTH fans? Will this cause any issues? BTW, I am not running air conditioning. Any help would be greatly appreciated and if anyone has any additional hints or advice for wiring this up I would welcome that as well!

[badazz81z28]

I have the same harness. The ECM controls the relay that opens and closes the power to the fuel pump. You want the ECM to control this function. However I’m using a PWM, so the power that’s supposed to run the pump now runs my switch power for the PWM and the pump wiring is connected to the PWM. Since the wire gauge off the GMPP is not sufficient imho, I would suggest you do what I did and use that wire to control your relay. Essentially the computer will control the relay that will power your external fuel pump relay. As for the fans, both trigger wires are in parallel. I added another relay in the gmpp fuse box for fan #2. You don’t want both fans on the same circuit as they pull too many amps and it will surely pop the CB.

[icemanrd19]

This will helpmyou a lot. I already asked on the stupid questions back in the day. Now to me it’s very simple.

https://www.pro-touring.com/threads/117816-gpmm-ls3-controller-help

[Kmart78]

This will helpmyou a lot. I already asked on the stupid questions back in the day. Now to me it’s very simple.

https://www.pro-touring.com/threads/117816-gpmm-ls3-controller-help

Thank you, a lot of helpful information in your thread!

[badazz81z28]

For SA, for the TACH you don't need to add a resister. There is another pin-out on the ECM that you can splice into the Tach wire and it will allow a autometer to function correctly. As for the OP, I used a direct wire from the autometer sender to the gauge (no ECM). I added a new relay for the Fan in the GMPP. I'm kind of shocked how much re-wiring I had to do the fuse box...Funny how GM wired both fan signals *2 pin-outs into the one and set up the fuse box to operate one fan despite it being capable of being wired for 2. As a back-up using a sensor in the radiator.

[DT69Cam]

The Grey wire from the fuse box (GMPP) is your fuel pump wire. Wire it back to your pump. For the fans, I went with the Entropy LSX fan controller. Super easy to connect and it works GREAT!! I just capped the Blue fan wire (GMPP) and didn't use it. Also check out Team Camaro. Its a great forum and has an LS swap section. Many guys over there done this swap with helpful wiring info etc. Here is my thread over there: https://www.camaros.net/forums/241-lsx-swap/436362-ls3-build-finally-moving-along.html

[badazz81z28]

Try www.nastyz28.com too.

Is there any difference running off temps on the radiator versus the head? One of the reasons I would rather have the ECM controls the fans.

[Kmart78]

The Grey wire from the fuse box (GMPP) is your fuel pump wire. Wire it back to your pump. For the fans, I went with the Entropy LSX fan controller. Super easy to connect and it works GREAT!! I just capped the Blue fan wire (GMPP) and didn't use it. Also check out Team Camaro. Its a great forum and has an LS swap section. Many guys over there done this swap with helpful wiring info etc. Here is my thread over there: https://www.camaros.net/forums/241-lsx-swap/436362-ls3-build-finally-moving-along.html

Thank you, I've been looking into the Entropy controller. I haven't been to team Camaro but I will go browse there as well!

[badazz81z28]

Thank you, I've been looking into the Entropy controller. I haven't been to team Camaro but I will go browse there as well!



Look into Dewitt too, much better radiator imho, American made too,

[Kmart78]

I've got a Dewitt's radiator!

[badazz81z28]

I've got a Dewitt's radiator!

Shouldn't need any special kits then. There is a temp activator for fans already in the radiator? All you need is a relay and power.

[dhutton]

Shouldn't need any special kits then. There is a temp activator for fans already in the radiator? All you need is a relay and power.

Fans will only have one speed, max, and it will be noisy. Entropy controller gives two speeds by connecting the fans in series or parallel and helps keep the noise down. Better yet a PWM controller will minimize noise.

Don

[badazz81z28]

My Dewitt has a slow speed and high speed fan. The fans themselves, it was pretty surprising when I got them. It’s a dual spal set-up.