SCOTTYSALESMAN

I am about ready to pull the trigger on a complete changeover LQ4 from an 02 Silverado. Everything, harness, MAF, computer etc. My questions are; I see a lot of articles on 4 wire hookup made out of the old harness. Is the 4 wire deal for both carb and EFI? What do I do with the huge fuse box? Is that discarded with the 4 wire conversion? Also, the change over I am looking at has an engine mounted fan not electric. How can I convert the harness for an electric fan?
Thanks in advance for any help.

deuce4935

iTrader: (2)

The 4 wire hookup is for efi engines. You can keep the "huge" fuse box or find a smaller one and wire it into the harness, but you will need a fuse block for efi setup. Are you planning on doing your own harness or sending it out to be modified? Iirc, the pcm will need to be reprogrammed with a F-body tune in order for the pcm to control the electric fan, or you could go with a radiator thermostat type setup that uses a relay and sends the signal to the fans to turn on at a set temperature.

SCOTTYSALESMAN

thanks , trying to modify harness myself. truck pcm cant be flashed for electric fan? If I convert to carb, do I use any part of the original harness or just use the msd box? Do you have to use any part of the computer for carb or is it eliminated all togetherr. Thanks again!

deuce4935

iTrader: (2)

If you're going carb, the harness and pcm is eliminated, the Msd box will need to be connected to the necessary sensors and coils. And the truck pcm will need to be reflashed with a f-body car tune in order for the pcm to control the electric fan. Check out www.lt1swap.com for instructions on how to modify your harness, the site has tons of good info and pics.

SCOTTYSALESMAN

thanks!

psiconversion

iTrader: (5)

Truck PCM can be retuned for electric fan control. It just needs to be 'activated' in the tune and the harness needs to include the trigger wires. You may want to consider a new harness as opposed to a rework.

71ANTICARB

iTrader: (23)

Of course you would. I redid my harness in about 8 hrs of actually working on including doing the research.

Theses helped alot:
https://ls1tech.com/forums/conversio...chematics.html

http://chevythunder.com/19992002_ls1...nk%20Connector

71ANTICARB

iTrader: (23)

https://ls1tech.com/forums/conversio...-diagrams.html

This one too.

deuce4935

iTrader: (2)

Should modding the factory harness become too overwhelming, consider contacting
wait4meperfromance.com, they have the best prices, the work is top quality and the price includes pcm programming.

SCOTTYSALESMAN

yeah, $750+ for a harness seems really expensive!

deuce4935

iTrader: (2)

Tell me about it. Its good if you can do it yourself, but if you have to shell out the money and you have a stock harness onhand, then wait4meperformance cant be beat, price, quality, and customer service is A+.

psiconversion

iTrader: (5)

$499 plus free shipping from PSI.

00Wildcat

jimsperformance he does a lot of 4x4 swap harnesses around $500 for rework and flash. there are relays and other small misc parts required + the cheapest reflash I've seen is $100+shipping so that puts the actual labor in the area of $250-300ish that's a good deal in my eyes.

deuce4935

iTrader: (2)

$320.00 @ wait4meperformance.com, includes harness mods, relays, pcm programming and shipping.

TomM

iTrader: (57)

You can do the harness yourself and save a ton. There is enough info on this site, and knowledge base to walk you through it. Click my sig link for some insight....

T,

Tamatt27

iTrader: (4)

I don't want to hijack the thread but is it possible to rework a Gen III harness to work on a Gen IV engine and PCM?

psiconversion

iTrader: (5)

Kind of a loaded question... anything is possible.

Other than wire routing, various connector locations and connectors are different. If you are going to rework your own harness you are probably better off starting with a Gen IV harness. Or you could buy new.