Most of you may remember me from my fuel pump problem earlier last year, well, the car has been running great since it's been fixed and all is well........except for the radiator fan. The thing is, I don't drive very far when I drive the car (only about 18 miles back and forth from school 2 times a week), and the car never gets hot (about mid-range 220-ish), though if I get daring and get stuck in traffic, the temp shoots up to 260 and I have to stop, or else the worst will happen. Now I have seen a couple threads that might help, but I'm not sure if its the same problem. You see, the fan doesn't work, yes. HOWEVER, if while the car is on AUX (before start), and I put a test light into this highlighed slot


DSC_0116 by ANGELSFAN14, on Flickr

The fan will turn on, though, if I have the car started, the fan won't turn on, and if I leave the test light in the slot when I start the car, it gets mad at me and acts funny, lol, so I won't do that again. So yeah, is it just the relay switch, or something more.....complicated (and please don't show me a wiring diagram, they make my head hurt )

 

I'm actually about to install a new relay, and after looking at a bunch of wiring diagrams/scenarios and what not over the past month it sounds like the power (+12v) for your fans (or whatever is turning them on) is connected to a auxillary wire of some kind.

Are the fans stock? Aftermarket? How are they wired up? I'm assuming stock since you're sticking a test light there. It sounds like you're completing the circuit when you use your test light, and otherwise it's grounding out. Could be a number of things.

I'm having a number of issues myself, so don't feel too bad!

 

Everything is stock, only one fan, and the wiring should be how it is in the manual. 3.1 v6 by the way.

 

No answers? Or is it painfully obvious? Could it be the thermostat thats not working right? Or rather, is the thermostat for the radiator fan the same as the one for the dial in the car? Because, as far as I know, the one in the car has a correct readout (because I can se a little steam coming out if its near the 260 mark ). If no one really knows, can someone direct me to a thread or something that discusses how to wire the fan to be on all the time? Would be much appreciated

 

The fan is supposed to come on when you ground the diagnostic terminal, do it the right way and don't randomly plug test lights into your OBD plug like that or you might ruin the ECM.

If it comes on with key on in diagnostic mode, that means your fans have power, and the relay is probably working fine because the car can turn them on at will.

The coolant sensor that tells them to turn on about 215-220 or so however, is not telling your ECM to turn your fan on.

Do a little research, because your car has two I believe, one in the intake, one in the rear of the head somewhere (not sure on this, look it up). One talks to the ECM, one talks to the gauge. Sounds like the temperature sending unit for your gauge is working, but the CTS for your ECM is not.

 

Also, they are a cheap part and easily replaced. Although they can be a pain in the you-know-what to reach sometimes

 

I'm having the same problem myself. The fan switch is located on the passenger side head between #1 and #3 cylinder. Be ready to pour coolant everywhere if you don't drain it first. I've replaced that switch, along with the coolant temperature sensor, and still haven't solved my problem. Frustrating as all get out. Good luck friend, and keep us posted.

 

The CTS lets the ECM know how hot the engine is, the ECM turns the fan on (relay, but, w/e).
The sending unit for the gauge is not a sensor.

I'll agree though, there is the possibility of the CTS giving a false (low) reading to the ECM, causing the ECM to not switch the fan on at 220°F.

If the CTS failed, completely, the car would not run well (if) at all and the check engine light would be on.

3.1 v6 did not have a fan switch. The 2.8 did.

 

I stand overly corrected

Yes. They call it a temperature sending unit when it controls the gauge.

Either way, the CTS is probably your problem. They tend to start reading low due to higher resistance with age, leading to your fans not turning on.

 

I noticed an empty green connector by the blower motor near the firewall. Is that where I can connect a dwell meter?