Croyston

I have a 1993 FD (MT) that is basically stock (GReddy downpipe, boost gauge, turbo timer). When I got the car it had some serious electrical issues and most of that system has since been rebuilt as has the engine. The car car currently runs normally except for one thing:
The problem I am having now is that the radiator cooling fans are running all of the time. From the moment I turn the car on (they do not run when the ignition is in the 'on' position but kick in as soon as the engine is turned over). i know that normally they are supposed to kick in once the car has reached a certain temperature and certain factors like the A/C being turned on can also activate them or change the run speed.
At this point, I have verified that fan relays #2 and #4 are definitely operating when they shouldn't be but the operation of the relays themselves is normal (as in they are not sticking). I cannot say for sure but my A/C switch appears to be operating normally (most of the system is currently not installed) and my best theory at this point is that there is something wrong with my electrical load unit that is causing the ECU to believe that one of the fan operating conditionals is being met.

Any advice or suggestions on components that could be causing this issue or ways I could test the functionality of the E/L unit would be appreciated.

Here's a quick list of electrical components I have already changed out:
-water thermoswitch
-water thermosensor
-water level sensor
-water pump
-fuel thermosensor
-wiring to the CAS (the sensors themselves are fine)
-Oil pressure sender
-ECU
-Air temperature sensor (not replaced, but verified operating normally)

Sgtblue

iTrader: (16)

I stink at electrical issues, but if you changed those switches and sensors, could you have inadvertently grounded something in the process?

Croyston

It's a possibility I suppose, but I would expect if I had accidentally grounded one of the related sensors wouldn't I be pulling a code?

Sgtblue

iTrader: (16)

As I said, I stink at electrical issues, but I don't think so. Not for the thermoswitch.

Johnny Kommavongsa

iTrader: (13)

make sure u have a good connection on ur thermoswitch a loose connection will make them stay on.

also what happens when u disconnect the relays?

Croyston

Problem Solved:

As it turns out, I had two different versions of the service manual. In one version, there was a connection made through terminal O of the electrical load unit that connected it to thew fan circuit and terminal 3B of the ECU. This connection was not present in the other version of the manual that I have. As I mentioned in the original post, I have changed out the ECU for a factory rebuilt one because my original ECU was dead. Apparently, even though my wiring harness corresponds to the wiring diagrams where that connection is made at terminal O, my current ECU was not programmed for that connection to be there. As soon as I removed that connection (clipped the wire just before the load unit), the fans operated normally. Thanks to everyone who gave suggestions.

borisf

Would it be possible for your to take a quick picture of that of the corresponding wire that you clipped?

The previous owner of my FD wired the fans to work as soon as the key is in Accessory... which is great for cooling, but taxing on initial start up.

Thanks for your help.

Croyston

Yeah sure thing, I'll take one this weekend when I work on it.