Fan Not Working - Can I hardwire it?

[DeepPower]

Fan on my '89 SHO isn't working and car overheats when sitting at idle too long - it spits out coolant from the overflow. Ran the codes and it said my coolant temperature sensor was bad. Replaced the sensor, but fan still isn't working and car overheats at idle so it's probably the fan control module.

I ordered a new Four Seasons 37510 Cooling Fan Control Module which I should receive Thursday, but in the meantime I'm turning the engine off at stoplights and, just to be safe, I'd like to hardwire a switch to turn the fan on. Even when I install the new module, in the Texas July/August heat it might be a nice thing to have. Has anyone done this before? Is it as easy as I think it should be?

Thanks!

 

[sperold]

The module will probably save you in the long run, but you need something now.

I ran the fan directly with no problems with a toggle switch.
First, figure out if the fan still works by unplugging the connector and running a wire from the battery to the fan and then from the fan back to the battery. If the fan comes on, then you have a working fan. Tie the original connector up out of the way so it doesn't get wound up in the fan.
I looked at the original connector and took note of the wire size and got a similar wire in a roll (25 feet of 12 gauge I think). I got two eyelet ends that had a hole large enough to go over the bolt in the battery terminal and crimped them to the wires. Put an inline fuse (30 amp) on the positive terminal. Run the wires into the cab any way you can (even if it is exposed from the back of the hood to inside the front door post). If you don't want to buy a toggle switch, use a household light switch but wrap it in electrical tape as all the screws are exposed. Put that near your console to make life a little easier. Make sure that the fan is turning in the correct direction to draw air into the engine compartment.
The fan connector is just two individual push-on type connectors, so you can switch the individual wire connectors to reverse the fan direction.

 

[pjtoledo]

Fan on my '89 SHO isn't working and car overheats when sitting at idle too long - it spits out coolant from the overflow. Ran the codes and it said my coolant temperature sensor was bad. Replaced the sensor, but fan still isn't working and car overheats at idle so it's probably the fan control module.

I ordered a new Four Seasons 37510 Cooling Fan Control Module which I should receive Thursday, but in the meantime I'm turning the engine off at stoplights and, just to be safe, I'd like to hardwire a switch to turn the fan on. Even when I install the new module, in the Texas July/August heat it might be a nice thing to have. Has anyone done this before? Is it as easy as I think it should be?

Thanks!

which temp sensor did you replace?

the single pole sensor goes to the temp gauge only, the double pole sensor is what the PCM uses to control the fan.

fried connectors at the fan are common

the engine fan is supposed to turn on if AC is selected.
it should also turn on if the cabin fan is turned all the way up, in ETAC equipped cars. Not sure about manual AC cars.

an auxiliary switch (with fuse) should work, I would wire it is so that the switch will only send power the the fan, not back-feed the normal fan circuit. there may be a defect in the circuit that is better off without power.

since your SHO spend time up in the great salt belt, corroded wires and connectors are a definite possibility. On several occasions I've found green gunk where copper wires used to be.

Perry

 

[DeepPower]

Thanks, @sperold. I could have eventually figured it out myself but time is important here and I needed shortcut instructions.

@pjtoledo, I replaced both sensors, the gauge temperature sensor and the coolant temperature sensor. They are near each other so why not replace them in pairs. I also replaced the thermostat with a new Failsafe thermostat because, again, I'm already there. In the morning I'll try turning on the AC and also turning on the cabin fan and see if the engine fan turns on, thanks for the info on that.

 

[rubydist]

ccrm is suspect from the symptoms you describe.

 

[dinglefro]

You can either run a toggle switch or just run a relay and jump it off a fuse that is powered when the ignition cylinder is in the on position.

 

[DeepPower]

Update: I got the CCRM module yesterday (FAST!) so I installed. Fan still does not work. As the temp gauge was all over the place the day before I also burped a lot of air out of the cooling system using the engine off, squeezing the upper radiator hose method and added a bottle of Water Wetter.

However, I remembered that about a month ago I got home, pulled the SHO into the garage, turned the car off and the fan refused to turn off, symptom of a bad Constant Control Relay Module (CCRM). After ten minutes I had went and pulled the fan connector to turn the fan off. The next morning I had connected the fan connector and the fan was not running. Probably that is when the fan stopped working for good and I just didn't notice in the unusually cold Texas winter.

After yesterday I tested the fan at its female socket and saw resistance so the fan is probably good, but it took awhile to get the paperclips I plugged into the female to make contact. The contacts on the male connector are green and slimy and I did my best to clean them.

At this point with the bad CCRM replaced the connector is suspect. I would have done more but it was getting dark, my sinuses were in red alert mode from my first spring hayfever in Texas, and the prehistoric Texas flying insects refused to leave me and my trouble light alone. I think one of the larger ones tried to carry my SHO away to it's lair... Anyway, I'm going to run the KOEO diagnostics and see if there is voltage at the male fan connector so I know if it is supplying voltage to the fan. If so, I'll cut out the connector and hard wire until I can replace the connector. If the fan still doesn't work then, I'll install the switch.

Also, after yesterday I would like to introduce Bill's Law of Trouble lights, which states:
No matter how carefully you hang your trouble light, it will always shine away from your working area and directly into your eyes.

 

[dinglefro]

You don't have to cut the connector. Just plug some small male spade connectors into it. Then use some electrical tape to hold them in and covered. That way when you do figure out what's wrong you won't have to anything but disconnect the wires you ran

 

[DeepPower]

You don't have to cut the connector. Just plug some small male spade connectors into it. Then use some electrical tape to hold them in and covered. That way when you do figure out what's wrong you won't have to anything but disconnect the wires you ran

Actually, it's the female connector (on the fan side) that still has the mold in it. And because it's female I can't "see" inside to determine how clean it is so I can never trust it. So I'm going to cut that female connector and for the time being get some small spade female connectors for the fan side to connect to the male. At some point I'll replace the entire connector assembly with heavy duty automotive connectors.

I know there's a dirty joke here somewhere...

 

[sperold]

If you get the correct size male barrel or spade connector, it will work even though the fan side is green. The one I did was green also. Do the direct connect with 2 wires to the battery to see if the fan runs. If it does, you are in good shape.
Since this might be more than a few days, you might want to look for a way to run the wires into the cab in a little nicer fashion than the exposed way.
I ran mine into the door and mounted the switch on the door panel, but somewhere on the console is fine too. Just look for a place that making a hole is not an eyesore later on when you solve the issue.
I never did solve mine after I tried a lot of parts to no avail.
The system worked good for me for as long as I needed it.