Hello,

Well for some reason my LS1 PCM is not putting out anything for the fan relay, so the fans wouldnt not turn on at all. Ive directly wired up a fan switch temporarily so I can at least drive the thing...I was wondering if there is some after market fan switch where I can just feed a temp. wire to it and it turns on the fans with its own relay? How would this work? http://static.summitracing.com/globa...ss_install.pdf

Could I simply splice off my current temp wire or would I have to find a place to tap into the water jackets (which I am avoiding like the plague)?

Any info is appreciated. Thanks

Chris

 

If I read correctly, you are looking for voltage at the PCM fan relay pins?

I believe the PCM grounds those pins, not applies 12V, when the fan is requested.

 

Well whichever the PCM does, its not doing it. I wired the PCM output to the stock relay and it wouldnt turn on the fans. Unless I didnt let the motor warm up enough, but it went past 220* and no action from the fans.

**So you are saying that I should see 12v out of the PCM for the fan relay? Ill have to check that.

 

No, I was trying to say the opposite. The PCM switches the GRound side, not the 12V side of the circuit.

Take the dark green/wht wire coming from the fan relay and ground it while the ignition is on. The fan should run.

If the fan doesn't run, unplug the relay (key on), test for 12V on both the brown and the red wire. IF thats ok, jumper the red and blk/red wires. The fan should run.

If it does run, the PCM is not grounding that wire like its supposed to. Either you've got the wrong pin on the PCM for fan control, the fan control circuit in the PCM is fried, the coolant temp sensor is faulty, or some other condition is preventing the PCM from calling for the fan.

 

Oh ok I see what your saying. I was just a little confused. The only problem now is im not sure if I cut the wires going to the fan from the relay in order to get the switch working...I hope not. Ill see what I can do with it. However I think it might be something with the PCM, because I am also not getting a tach output signal. Everybody is saying its a grounding problem, but I dont know where to start with that, I have all the grounds attached.

The worst part is were doing electricity and magnatism in physics so I dont want to see another circut diagram ever again...haha.

Thanks for the help,
Chris