Hey guys, I’ve lurked here for a long time and have found alot of useful information. However, I’ve came across a problem I can’t quite figure out on my own and can’t find specific info to my problem searching.
Here Goes:
I have a 1990 GS, with a half size pwr radiator (stock type wiring setup), and my radiator fan doesn’t seem to be kicking on when it should, or at all, for that matter. From my searching, I’ve found some troubleshooting tips, and so far i’ve:
Jumped the green/yellow and black wires at the ECTS, fan came on.
The fan also comes on when I supply a ground to the blue wire’s terminal on the relay.
No matter if the key is off or on, the only continuity (ground) I recieve from any of the terminals on the relay is from the black line’s terminal. I DO get 12v power on the blue line’s terminal.
Also, I found this odd: When i test the plug on the passenger side for the fan, I receive 12v power. However, when I test the driver’s side plug, I recieve no power, but have a ground…is this normal?
Does any one have an idea of what my problem may be? I really appreciate any help, I’ve worked on this thing all day and have read non stop, and can’t seem to come to a conclusion. Thanks!
If jumping the terminal on the ECTS plug turns on the rad fan then the problem is the ECTS.
Because the fan comes on when you jump it tells you everything after the ECTS is good, [wiring, relay, grounds and powers].
Rad fan will come on even if ign. is off because power to rad is 12V+ constant, rad fan relay supplies the ground, ECTS supplies the rad fan relay coil with a ground, radiator fan control module supplies the rad fan relay coil with 12V+, all the above must be good if jumping the ECTS plug terminals turns on the rad fan, leaving only the ECTS as the problem. 94
Just the guy i was looking for. Thanks alot man, I read through alot of your posts on the subject and you are always very helpful. I guess I’ll replace the ects then!
While we’re somewhat on the subject, do you have an opinion on properly wiring the fan to the switch, or even to kick on when the ignition is on for that matter…? I’ll be boosted here soon and would like to have a little more control over the fan in the summer months. Thanks alot!
Easy, leave everything as it is and use a switch to supply a ground to the rad fan relay just like the ECTS does, [parallel with the yellow/green lead to the rad fan relay].
You do know it makes no diff. when you boost, ECTS will still turn rad fan on when engine coolant reaches about 194 degrees F.94
So I just installed my new ects, and no change. Fan still won’t engage. My temperature needle sits at a little less than half way at all times after warm. I don’t think it’s accurate though, as I’ve left it sit for quite awhile and it never gets warmer than that, even on 60f+ days, and the motor gets that “hot smell”. Are there other diagnostics I could run? Is it possible I need a new thermostat?
Weird thing is, I bought the car wrecked, needed new core support. When I first got it (before repairs) and driving off the trailer, the fan ran, albeit at an odd time (when outside temp was in the single digits). It even would stay running after the car was off. Could this be a clue? Could it in fact be the thermo?
Should also add that both the upper and lower radiator hoses are pressurized and warm when the car is running.
Wait… are we confusing “Engine Coolant Temperature Sending Unit” [ECTSU] that is connected to the “Engine Coolant Temperature Gauge” with the "Engine Coolant Temperature Switch, [ECTS] that is connected to the rad fan relay???
One has nothing to do with the other, other then monitoring engine coolant.
If both upper and lower rad hoses get hot it is an indication of a thermostat that is opening, or stuck open, but a new thermostat can’t hurt in a car as old as a G2.
Because the rad fan came on when you jumped the two leads in the plug to the ECTS the circuit has to be good, all the ECTS does is “jump” those two leads when coolant temp gets hot enough, [about 194 degrees F] if a new ECTS is not turning rad fan on then engine coolant is not getting hot enough, which would mean a thermostat that is stuck open.94
The fan is now coming on…I probably jumped the gun a bit in saying that it wasn’t remedied when replacing the ECTS, it just takes awhile to get warm. Probably couldn’t hurt to change the thermostat. Thanks again, you were alot of help.