So I need some assistance getting the wiring sorted out for my '99 ls1 swap into a 91 firebird.

I'm using the stock 3rd gen compressor and fan relays. LS fans and radiator.

Got it running, but am receiving a Fan circuit code for both fans from the PCM.

If I unplug one of the relays, the codes go away.

The PCM does not turn on the fans at any point, and I've had it up to 242*. The fans settings were lowered to 210ish IIRC.

If I turn the ac on, both fans come on. So I have them working persay, but I still want the PCM and the ac to control them.

My system is still charged with the original R12 and is blowing ice cold. I have no desire to open the system just to add the ls1 variable pressure sensor to it.

My searchs on here and ls1tech haven't turned up too much.

thanks

-jason

 

LS1 PCM's employ a low speed and a high speed fan circuit. In order to not trip codes you have to find the diagram in the swap sticky over in the hybrids section on how to wire duals fans to avoid codes. Do you have the PCM controlling the A/C or do you still use the factory third gen wiring? You definitely want to control the A/C with the LS1 PCM so it can work the fans properly ( which you know you can tune to work however you wish ) Also I would lower the fan temp to 10 degrees above thermostat or even 5 degrees above thermostat temps.

 

well maybe thats what I'm missing. I've been searching for ac wiring info, rather than fan wiring info

odd note, if I take the pin out of the PCM and ground it, both fans turn on.

Good point on programming the ac portion of the PCM. I guess you could set it to whatever you wanted to basically bypass that sensor. Shame I don't have the software to make that happen... could be a reason to try it though

-jason

 

Yeah the software is a VERY handy tool to have indeed. I dont have it yet either but I will be getting it the next time I do mods. I was very fortunate though that my tuner was cool and kept tweaking my PCM when I threw codes. I was throwing codes for about the first 2-3 months after my swap for various things but the cooling fans were the most trouble some. I only run one fan ( stock in my car ) so I at first wired up the high speed only circuit to feed it but I found out that the high speed ***** off when the low speed is called for so they didnt work. The fox was to wire both the low and high speed to the same cooling relay in my case.

In your case I think you'll find your answers right here

http://www.ls1tech.com/forums/conver...gram-here.html


If you dont find the right answers there check in the LSX swap FAQ and hall and hall of fame sticky in the conversions and hybrids section.

 

Ahhhhhh, I see the trees in the forest now

I only have it setup to run the fans at high speed. Now it makes sense.....

I'll just add the 3rd relay for the low speed and see what happens

thanks

-jason

 

FWIW I have both high and low speed running to the same relay spliced together. i figured seeing as it ***** one circuit down when the other fires up it would work okay and it does so you can avoid adding a third relay if you want. I dont think it would hurt to add it mind you but it might be faster to not bother.

 

Good tip, I might give that a try later on

right now, the car is going for exhaust work. Then I'll worry about the fans

thanks

-jason

 

Looks like you found your answer dude! COngrats!!

 

We shall see when I get the car back

/me crosses fingers

thanks

-jason

 

Theres tons of guys on here who will help with whatever they can so long as it looks like the OP has at least taken the time to isolate his/her problem and put their own effort in before asking for assistance. Theres nothing more annoying than having some pecker wood ask a question thats been asked a million times or looks as if they clearly havent even read the stickies and then gets snarky at anyone who doesn't give them the kind of response they think they are "owed" so I have pretty much taken the policy now that i will only post in things that either interest me or in threads that have solid questions ( not previously covered )

I like to help and give back to the boards hence my writing of the sticky but some of the attitudes of the new fish... geez...

Anyways rant over good luck with the fans post up if you have any more trouble.