Drewdude

Hi guys, My radiator fan runs all the time (when key is turned, when motor cold, etc.). My fluid temp sensor (in passenger side rear half of block) only has one wire going to it. I unplug it and same happens, even if I ground the wire.
Any ideas? Sorry if this is really obvious...I'm new and looking for tips. Thanks!

aklim

First idea is fill up the profile so we know where you are, what car you are working on (in this case, specified).

Before we go there, what does the ECM think the temperature is? Assuming you have got the right wire. They might have one for the gauge and one for the ECM. IDK about 89 but in my 91, there is one for the gauge which is absolutely meaningless to the ECM. If the ECM thinks it is hot, it will activate the fans. Is the AC off also?

vader86

Fan runs anytime ignition is set to Run?

Someone has wired it to a 12V switched source, probably from the fan relay to something like the wiper motor.

Drewdude

Thanks, I filled the profile out just now (yes, newbie, sorry)...
I've got the Haynes manual now (FSM is in the mail..), and it is the only sensor I find. The digital gauges inside ramp up normally...when cold, it shows low, then starts eventually showing a temp and then counts up to 220 or so when 'hot'. Fan runs all the time. AC is off. If there is another for ECM that runs, might explain..just have to find if so. I also wonder if PO has hardwired it somehow even though I do find the fan relay that appears to be normal..

Drewdude

Yes, anytime. I've followed the wires and seems 'stock', but will look again. Thanks.

WVZR-1

Do you have a 'CEL' (Check Engine Light) or 'SES' (Service Engine Soon)? In the DIC with the key turned to ON but NOT RUNNING what is lit in the DIC?

If there's nearly any ECM fault the cooling fans default to on.

The rear right single wire isn't related, that's the temp gauge sender.

KEY ON > NOT RUNNING for an early car I'd think you would have SES but it would go out at CRANK and RUN. For sure RUN unless you have a ECM fault.

Drewdude

The lights come on for key on as expected, but it goes out after a few seconds, same after starting. No CEL activity past that.

aklim

In my year, it is right under the throttle body in the intake manifold.

Hard to say without tracing the wires. Right now, without the FSM to guide you, I'd say that unless you open up the wire looms and see obvious signs of hacking, it is going to be difficult.

Sleazy Rider

just a stretch here but...we used to disconnect the connector in one of the a/c lines to turn on the fans all the time. outside temps here in texas really do get high and the additional airflow through the radiator did help.