Engine coolant fan wont cycle

xeroinfinity you there? My 1993 2.3 GA. wont turn on radiator fan, even @ around 260F. Fan runs if i start engine & disconnect ECT sensor plug. Fan runs if i jumper adl @ a&b with paper clip, and koeo. Fan runs when i select a/c swith on. Fan runs if i unplug it and jumper 12v. to it. I admitt defeat, what am i missing? i installed new thermostat, and coolant sensor. Please help as i cannot drive this car overheating like this, with no fan, im afraid ill ruin it. Thanks to all.

I forgott to add, There are no codes present, only the "12" code. i can disconnect the throttle pos. sw. and a code will be set and, i can retrieve it from ecm. i dont think ecm, is bad, as it is communicating. But i could be wrong. will a bad ecm fan driver circuit work in diagnostic mode, but not in "regular" controll og fan, at operating temp? Any, help or ideas what to check/do greatly accepted. Anybody?

My quick guess on your problem, kind of sounds like the ECT Sensor is bad. If the fan runs without it connected and the fan obviously works, I would take a good guess and say that would be the culprit. I doubt the ECM would have anything to do with it... cause this is the only problem you are having... more things would be going wrong if that was the case.

Will the ect sensor still work to ground, if the threads are coated with pipe sealer "dope"? i have heard this would interfere with a proper ground, true, or false? i installed a new ects sensor, and fan still dont operate. what to do next? Thank everyone here, very, very much.

Sounds like you need to check out the wiring for the ETC to and from their root connections.
Dope sealer will impead electrical properties,
I'd clean that off and use teflon tape :thumbsup:

Also double check the fan relays and thier connections/circuits.

Hope that helps!

Thanks grfnkl, and xeroinfinity. Then based on the info above posts, do you think my ecm computer seems ok? And would i remove the plastic spiral wire covering all the way from the ects sensor, back to the ecm? looking for damage to yellow or black wires? i have 5 volts koeo, engine cold, at ects yellow sensor wire, so this would leave the black sensor ground wire, as possible trouble maker? what a pita to get at those wire harnesses! Thanks men.

have you checked fuse/relays under hood(engine compartment)??

inafogg, thanks. ill check them in the A.M. Where would the underhood fuse box be located? I know inside the car, but not underhood.

Thanks grfnkl, and xeroinfinity. Then based on the info above posts, do you think my ecm computer seems ok? And would i remove the plastic spiral wire covering all the way from the ects sensor, back to the ecm? looking for damage to yellow or black wires? i have 5 volts koeo, engine cold, at ects yellow sensor wire, so this would leave the black sensor ground wire, as possible trouble maker? what a pita to get at those wire harnesses! Thanks men.

Have you tested for power at the fan harness ?
Does the fan work with the AC on ??


Also your car should not be overheating just because the fans are not working.
If its getting that hot then you have other issues causing it to over heat.
These are made to run at operating temp without a fan, but I understand if the fans not working then thiers a problem and a reason.

The relays are along the firewall I believe.
Not sure which one(s) exactly because they get moved around....

take a look you will see them/fuse box probolly near the battery.it will have a cover on it & is marked.it maybe something else like they have stated but atleast check the obvious first Good Luck

inafogg, & xeroinfinity. This car 1993 grand am 2.3L does not seem to have any fuse box under the hood. Has one on side of dash, inside of car. The relay and its circuit for the coolant fan, and ecm fan driver, is good as it turns on the fan when adl jumped, @ a&b terms, and key on. Likewise, when i diconnect connector to ects, engine running, fan will run. so fan wire harness must be getting power. When i plug the ects back in, engine on, fan stops. I have 5volts at the ects sensor on the yellow wire comming from the ecm. i changed the ects, and thermostat, no help. do you think i have an open black sensor wire ground, or dirty connection? Or does this point to a bad ecm ? Seems the ecm either is not gettng any temperature reading from sensor, or is confused about any temp data it may be getting. Should i open a new thread, as im getting this one pretty long. Im only thinking of the other people needing help too. Deep thanks.

I never said thier was a fusebox under the hood.
The relays are under the hood on the firewall, thats what I said.

Like I said previously, make sure the etc sensor is grounded. If you can jump it and it runs then thiers a problem in the cicuit(s).

Then you'll probly need to inspect the wires going to the ecu as they sometimes break or become corroded.
If that all checks out then I would think about having the ecu tested at the stealership or replace it.