Wiring harness - Painless, R***gade, or self done?

I purchased an 02 LS1 out of a WS6 car with full harness. I was wondering what people have done for wiring - Painless universal kit or the other guys $800 modded Ls1 harness or just spliced the factory Ls1 harness.

Thanks

2009 LS3 here. Did it myself. If you can read a schematic, know whats not needed (A/C etc), and dont mind the challenge, youll be fine.

All those guys do is tear out wires that arent going to be used, add in a fuse block and relays, and tape it back up. Whats left is a stand alone harness. It took me about 2-3 hours to trace my way through it all which for those guys at $100-125 per shop hrs is about $375 and then they add in coverings like convoluted tubing and such at ~$50-75 for the good stuff and then ~$100 for fuse block/relays and such....you can see why they charge that much.

I ordered:

2 x relay socket PN# SRLY-2 from [You must be registered and logged in to see this link.]
2 x relays PN# RLY-351 from [You must be registered and logged in to see this link.]
8 x female connectors PN# 571-42238-2 from [You must be registered and logged in to see this link.]
4 x connector locks PN# 829-12160437 from [You must be registered and logged in to see this link.]
6 x female connectors for ALDL PN# 829-12129373 from [You must be registered and logged in to see this link.]
1 x ALDL connector PN# 829-12110250 from [You must be registered and logged in to see this link.]
2 x fuse blocks PN# DOR 85668 from [You must be registered and logged in to see this link.]

The above parts total $28.75 (I ordered extra female connectors here and there in case I lost or brake one). The above is all the the parts necessary to convert a factory harness to standalone which consists of the ALDL connector that goes under the dash, fuse blocks and relay center to power the computer and harness as well as the fuel pump. Whats NOT on the list is harness coverings....I'll leave that up to you. But Painless makes a wonderful weave wrap thats mighty pretty. The neat thing about the dorman fuse blocks and relay sockets is that they are modular or they simply "stack" or snap into each other to make a one piece unit. You can buy three or four of the fuse blocks and they all snap into each other to make one and then you can also snap in the relay socket above the fuse blocks.... like this....
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Tuning the computer for standalone i.e. delte rear O2's, delete emissions, delete AC, etc is another story. I havent gotten to that just yet.

Seriously, add all those parts in a package, and I bet you could sell it for $100. I know I would pay someone to shop for me for $75 for all that little crap. I live in Canada, where shipping takes such a bite out of anything that is affordable.

wow great info. I might be inspired enough to do it myself. 944-LT1 have you considered doing the harness mods for others for cash?

Absolutley not! Seeing what others go through is enough to keep me a far distance from such ventures, for sure.

Im not an expert nor do I have the credentials to do something like that. If Im in a position to either pay to have something done or do it myself, I will 99% of the time do it myself; for the challenge and pride of knowing that I did something others charge big money to do. But after that, doing it for others/strangers...the fun is simply replaced with fear and liability.

If you decide to do it yourself, you should always know that this entire board is here to crutch you through it. But you never know...you may find that it is easier than you thought!

I also found a source for custom LS1 harnesses here:

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By all means do it yourself. It is quite simple once you have all the correct information.
Please refer to the images posted in my personal gallery (bridar). Don't be scared by the complexity of my descriptions, as I tried to incorporate as much original equipment and options from the Porsche. e.g..cooling fans, fuel tank venting, guages, AC, etc.

Great work. I have been reading your posts on wiring the A/C on the old board.

how does the fuel pump get worked into this? Is the stock 944 unit used for the LS1?

the harness I purchased had the relay and a fuse for the fuel pump from the ecu to the stock 944 pump it self. You just have to hook into the original power wire with mine. Your setup should be similar

You can use the original Porsche fuel pump, fuel pump relay, and wiring if you so desire. For Instruction on doing it this way refer to my photos in the gallery. Mine work just fine in this manner and still uses the LS1 PCM to control the pump. I did have my original pump go out on me, though it was not related to the modifications. I replaced it with a Walboro.

What about the fan relays?

I know some have it setup for the fans to plug into the ecu. Mine I have setup on its own relay. The renegade kit keeps the fan in a standalone setup.

The fans intial current at start-up is extreme, but only for a split second. I used to use a standard 40A automotive relay but had to replace it on what seemed like a yearly basis. So, I now use a 70A tyco relay.
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They cost about 18-20 bucks but are much stronger than the 40A relays. Havent had to replace one yet. I only use one speed of the two speed lincoln MK VIII fan so if you want two speeds, you need two relays. The fans can be conrolled by the computer or a temp sensor in the radiator. My radiator has a sensor in the drivers side tank so thats what I use.......

Mine I have setup on its own relay. The renegade kit keeps the fan in a standalone setup.

......Exactly.

Ok, so I can just have the fans either off or on full bore. If that is the case then I need to provide the relay above with a ground and +12v from the battery as well as a signal from pin 42 on C1 of the blue ECU plug (circuit 335), right? That way I won't have two speeds and only need to worry about wiring in one relay. Will this work or will the fans shut off when I get to the really high temperatures because the ECU will trip the output for the high speed fans and kill the signal for the low speed fan control?

Ok, so I can just have the fans either off or on full bore.

No, you dont have to do it like that. Depends if your fan has two speeds or not.

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If that is the case then I need to provide the relay above with a ground and +12v from the battery as well as a signal from pin 42 on C1 of the blue ECU plug (circuit 335), right?

Im not sure but the pin out I see for a 2004 GTO is: C2 pin 33 "High Speed Cooling Fan Relay Control" BLU/WHT.
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That way I won't have two speeds and only need to worry about wiring in one relay. Will this work or will the fans shut off when I get to the really high temperatures because the ECU will trip the output for the high speed fans and kill the signal for the low speed fan control?

Im not sure what you mean. If youre at high temps, the ECU will only provide signal for high speed fan. When the computer calls for low speed fan, nothing will happen, the engine will get hotter and then call for high speed fan. When you have your computer flashed, you want them to lower the fan contol setting so that your one fan speed covers the entire temp range of the original two speed fan of a GTO.

yeah, that's the same pin as I see for the high speed relay. I just emailed Brendan from LT1swap to see how he set up the cooling fan outputs. The turbo's did have twin speed fans, I think there are three wires in the plug (not sure I'll have to check next weekend). Ground, +v for low speed, +v for high speed. If the high speed fan isn't set low enough I'll just have to wire in two relays instead of one.

Is the temperature sensor the ECU references already in the engine somewhere? Or is the sensor listed in the conversion manual necessary for this function (I think its sole purpose is an aftermarket temperature gauge though).

If you are planning on A/C and want the two fan setup, do yourself a favor and get a Camaro/Firebird ECM. That's what I did, the A/C select and low spped fan are in the body control module of the GTO. It's not worth the effort, unless you don't want A/C or low speed fan then you are good to go.

I want neither, so great! Good to know though

Can't you just get the GTO ECM reflashed to turn on a pin for the fan control and the A/C input?

That's what Brendan did, I now have a high and low fan setting.

I f I remember correctly, the GTO ECU was missing those pins, but I'd have to dig it out and check. If they are there, then I have a viable spare ECU.

I posted before I saw your reply, so I guess I have a spare, but I didn't have a Camaro tune to program to it, now I do.