Has any one done this dual fan swap and used the pcm output to the relay for both cooling fan relays. Is it setting a code? On my 3.4 swap I tried to run both relays from one signal out of the pcm and it saw that the relay signals were out of range. whether it was because the one was unhooked or the other was doubled up I dont know. It appears that the pcm monitors the relay resistance to tell if the relay is shorted and sends a mil request if anything is wrong.
Im not saying that your definetly going to run into a mil light but it may be a possability.
01 cav w/01 3400 gam gt 4t45e
I know this thread is ancient, and bumping a 6 year old thread probably isn't a great choice for a first post. But.....Looking at an 01 tune with HPTuners. I see that there are settings for 2 fans or 2 fan speeds. On v6/v8 PCMs I've seen, this means there are two pins for electric fans. I'm wondering if it's the same with the 3dr gen Cavy PCMs.
I'm going to try and find a PCM pin out because I wouldn't mind having a better fan (which is controlled by the PCM) on the 01 4dr Cavalier i just bought.
While there are two settings in HPTuners for two fans...changing the second fan setting does nothing at all. There may have been thought of the PCM controlling another fan, but I bet they were lazy and just left the programming in. Now if there is an unused pin coming from the PCM...now that could be interesting.
If I get time maybe I'll look up the pin outs from the PCM.
- fans.gif (13k)
The above is the same layout as the v6 pcms in hptuners. I'm running the grand am gt dual fans but on the grand am pcm, with the correct wiring to the two relays. But all the diagrams I have seen of the jbody's there is no pin for it. Though if the pcm was shared with another gm car that had duals, the pin may possibly be the same. As for wiring them up the grand am setup for the dual stages. Is it supply's 6volts for low and 12volts for high, something like that any way. You may get away with hooking the other fan into the same jbody relay or look at the relay stock for the trigger wire from the pcm. Then wire up a different relay for the 2nd fan ran of the stock relay trigger wire.