So...if you guys have been following my other thread, I couldn't get my damn car to turn off for a while. There was a short in my fan relay wires that was causing this. I got new plugs and everything and now the car acts normal...except the Fans don't come on anymore at the temp specified in the PFC. In fact i'm not sure if they ever come on.

Here's what i know:
-Fans come on when I turn on A/C
-Fans come on when I short the TFA pin in the diagnostics box. (I believe this controls relay 2 and 4). Those are the only ones that click on when I short TFA.
-Relays are good I think. I have tested the coil side for continuity and NO COM side for no continuity. When I hit the relay with battery voltage over coil side, it clicks open and i get continuity on the NO and COM side.

I'm not sure what else i can test. I have the fan recall box and the patch harness. I've tested the fans without the patch harness and still nothing. Where do I go from here? I'm really not sure what else I can do.

Any help would be greatly appreciated. I have a track day coming up so I really need to solve this. Thanks in advance!!

 

Verify that pin 3D is +12V before the fan trigger temp, and then switches a ground once the trigger temp is reached.

 

Which Pin is 3D. Is it the same as Pin U on connector 1 of this diagram: http://www.innovatemotorsports.com/r...20-%201995.pdf

 

Okay I found 3D and checked it's 12V. It's always at 12V though. I then shorted the wire and the fans came on, so that means my wiring is still good (phew). But this does mean that my PFC is not sending ground when it should be. Is there any point in resetting the box and reloading the settings onto it? I'd rather not if I don't have to since i don't really wanna mess with idle learning again.

If it's not a software issue does it mean my pfc box is fried...

 

How hot are you letting it get? What temp is it set to? Post a screenshot of your fan settings in the Datalogit software.

 

Its gotten up to 93 or 94 and i have them set to 87

 

settings look fine. Here's something to check. Turn off ALL accessories. Warm the engine up. When you hit 87C, check that the ELD switch is on. This will show up in the monitor window of the software (make sure you have sensors selected when logging) or in the sensor/sw screen of the PFC.

The ELD indicator will only come on for two reasons: input from the Electrical Load Detection computer (headlights etc), or the fan trigger output.

 

ahh that makes sense. Btw what's the lowest temp that the PFC respects?

 

You can set it to any value.So if your ambient temperature is say 20C,then set the value to below ambient,say18C, and your fan will(should) run.This is the easy way to test functionality.

 

Okay that means there's no need for me to warm up the car? I can just do it while it's cold right?

 

yes you don't have to warm it up actually

 

I'll try it as soon as i get home. That will make testing MUCH faster.

 

You do not need to start the motor--just switch the ignition on.

 

Okay I just set it to below the ambient temp, and ELD came on, but no fans. I guess the pfc is pwned?

 

Okay I think I traced it down to the BJT transistor array in the PFC. The chip is NEC UPA1478H. Anyone have a clue where I can find one?

 

As a reference for other people looking for impossible to find chips, I found a site that actually carries it an doesn't have a $400 minimum order:
http://www.bdent.com/UPA1478H-p/upa1478h.htm

 

Just an update for you guys. I desoldered the chip that I thought was bad and soldered a new one in. And now it works!!! So yea apparently I did fry just this one chip. Hope this helps someone in the future.