Is the relay at least getting power? It might be some bad switch (eletronic transistor) that trips the relay also in the PCM. Just a thought.

 

Power flow is from the PCM to connector C107 to the relay You should have power at pin 85 with the a/c on. Pin 86 should not have any power at all. It looks like it goes to ignition from there. That is the control side.

The power side has a fuse in the PDC and you should get power to pin 30 and 87 with the a/c on. From there it goes to the motor.

 

Yup green nailed it. Also if your relay isn't getting power, check the constant (or key on power) for the relay and see if you get the 12v required there.

 

I'm not sure why, but the fan/relay is now working properly. May have been some light corrosion on the relay pins resulting in a poor connection, and simply re-seating the relay (multiple times) in its socket solved the problem (for now, at least). If it starts acting up again, I'll replace the relay.

Thanks for the help, everybody!

 

If the relay pins have corrosion just take some sandpaper and shine them up a bit. The contacts in your PDC box probably have a little corrosion on them too, for that I'd just get a small knife in there and scrape it off.

 

I have this same problem, unfortunately it wasn't solved by using Deoxit on the relay terminals (thanks anyway Dale, it was worth a shot, literally).

Previously I'd swapped the relay, tested the fuse and replaced the fan unit (did that yesterday). When none those worked I started searching, found this thread. Post #12 was particularly useful (thanks Mr. Green). I have no power on pin 87 with the A/C on. Can anyone tell me what this most likely means?

Thanks,
Scott.

 

Alright here's the deal. The relay is groundside switched and the fan is power side switched. There's also two fuses to check. One is in the junction block fuse 10 which is 10amps, this gives power to the relay. The other is in the PDC fuse 15 which is 50 amps, this gives power to the fan.

With the key on you should have power at pin 86 of the relay, if not check the 10 amp fuse. You should always have power at pin 30 of the relay, if not check the 50 amp fuse. With the A/C on you should have ground at pin 85 of the relay, this is the signal to turn the relay on and off. To check for ground just move your voltmeter lead from the ground ost of the battery to the positive post and stick your other lead on pin 85 of the relay. You should also be able to feel/hear the relay click on and of by cycling the A/C on and off. Pin 87 of the relay goes to the positive side of the fan to give it power to run which is the green wire on the fan.


Your problem should be somewhere in there, if the relay is clicking on and off then your fan may be toast assuming you get 12v on the green wire and a good ground on the black wire at the fan. Good luck.

 

Hey Evon, thanks for getting back.

I didn't really understand #12, mostly because I didn't really know if 87 meant 87 or 87a, either way I wasn't seeing voltage on it. Like I said, I just replaced the fan yesterday and it still isn't working, but I may have a DOA fan. Any way you know of to jumper it at the relay block in the PDC to turn it on without opening the whole thing up again? I know I did it once before but it was two years ago and I can't remember what I did. I think there's a way to stick a jumper wire into the right slots in the relay receptacle to turn the thing on. Clues welcome.

What I have now is the following. With Key On Engine Off, A/C set to "Max":

Relay Pin Circuit Voltage
---------- -------- ---------

1 85 12
2 86 5.6
3 30 12
4 87a 0
5 87 0

Sorry if the columns don't work right, I tried. They get screwed up when I save/post the message, don't know why.

Any thoughts on what might be wrong with these numbers? My fan fuse is 30 amps instead of 50 but I've never changed it and it tests good. So does #9.

 

You won't see any voltage at pin 87 with the relay unplugged because the power flows from pin 30 through the relay and out of pin 87 when the relay is installed and switched on. Yes you can jump the relay to see if the fan is good, jump pins 30 and 87 with the relay unplugged. Pin 87a is not used on this circuit. Careful though, the fan draws a ton of power so use some thick wire and just jump it only for a second to see if the blades spin, any longer and you could melt the wire right to the relay connectors in the PDC.

 

Thanks Evon. After some research (and a fair amount of head scratching) I remembered I could jump 30 to 87 and start the fan. The bad news is it started right up, I was sort of hoping it might be a bad fan.

Where I am now is trying to figure out why I get 5.6V on 86 with the koeo and A/C set to "Max A/C". My understanding is pin 86 should be tied to ground by the ECU/PCU (depending on your nationality) when the A/C is on, thereby closing the circuit and engaging the fan? Instead I see 0V with the key off, 5.6V with it on. The A/C position doesn't effect this.

Am I looking at the right pin? I've tried two different ECUs from different vendors, both exhibit the same behavior. As an aside, I cleaned the connectors at the ECU and PDC with deoxit along the way. Didn't help.