Fan works KOEO, but doesn't cycle on the road

Pablo94SC

Registered User
Anyone ever experience this? This is the second time it's done this to me and when I see the temp gauge spike I freak out. Car is tuned to kick to turn the fans on at 18x*, so I'm at a loss. I'm sorely tempted to get a couple of external relays, tap into the factory wiring and bypass the IRCM completely.
 
Idle. The fan is working again, but last night it decided it didn't want to kick on in the drive-thru at Wendy's. Temp shot up to above M and the A/C was off. Popped the hood and the fan(s) wasn't on. Did a quick KOEO test and the fans cycled. Started the car back up and the fan kicked on immediately and brought the temps back down to N. Been working all day as well. It's an intermittent problem that's happened twice that I know of. :confused:
 
i think the fans still use a relay with just a signal from the pc. in such case like all of the rest of the relays on these cars you could have a sticky relay.
 
i think the fans still use a relay with just a signal from the pc. in such case like all of the rest of the relays on these cars you could have a sticky relay.

It is a relay but it's a relay in an integrated relay module that is embedded in epoxy and is non-replaceable.

Could be a ground issue, or a bad relay.
 
fan

Sir, I also had the same problem. My mechanic did not just throw parts at it, instead he did some resistance testing-which I don't understand-but he diagnosed air in the cooling system which accumulated under the temp sensing module. If you look closely this module is higher than the bleed tube, thus he bled and bled to purge the air and now I am running normally with both low speed and high speed fans working. It worked for me and hope it works for you
John
 
It is a relay but it's a relay in an integrated relay module that is embedded in epoxy and is non-replaceable.

Could be a ground issue, or a bad relay.

So the late IRCMs are potted? The early ones are repairable.

Of course, you would want to get a voltmeter on the wires coming OUT of the IRCM before you cracked it open ...
 
I'm thinking either sticking relay in the IRCM or something is up with the ECT. I don't think it's an air-in-the-system issue since the first time it happened was before I did all of the work on the cooling system. I'm going to burp it one more time and check the voltage at the ECT against the thermostat opening to see if they corespond. If they do, good deal. If not, I'll replace the ECT and the gauge temp sensor and call it a day.

It is a Ford afterall and as we all know (or should), Ford's are notorious for having sensors go "bad" within the acceptable range. :p :rolleyes:

grumblefrickinTPSgrumble
 
I you should be able to test the status of the IRCM by tapping into the #14 and #17 wire. When starting the low speed winding, the EEC-IV will pull the #14 wire to ground. That'll trip the relay in the IRCM to run the fan. You could monitor if #14 is common to ground when the engine is running at a temp where you expect the fan to be on but it isn't. That'll tell you if the EEC-IV said to run or not.
 
I could do that Mike, but the problem is when it craps out it's a pretty quick climb in temps and the last thing I want to do is fish for the voltometer and #14. Usually after I shut it off I run a quick KOEO, the fan cycles normally, and everything goes back to normal. It's really strange.

My best bet would be run some external relays I have and see if it happens again. If it does, then it's the ECT. If not, then it's the IRCM. Either way, it's a pain in the butt. LOL
 
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