IRCM fan controller

Hasher76

Registered User
I have been doing a lot of searching and reading on the IRCM because I was having an issue where the cooling fan would not turn on, even when the temp went a little past the "M" on the gauge. I tested the fan and both speeds are working correctly. I measured the ECT and its reading correct, when I unplugged this the fans did nothing. I tested the wiring from the IRCM to the fan and the wiring is intact and grounded. I cut #14 and the low speed turns on (I have this wired to a switch). If I let the low fan run all the time, the temps would never get above the line next to the blue cold side, so the switch lets me keep it a bit warmer. Question is, is the IRCM bad or should I check something else.

BTW I do not have an EEC IV scanner yet, I am looking on ebay to get one so I can't do KOEO tests yet.
 
So when you pull the ECT sensor the fan doesn't come on? Huh, I wonder if that's because your IRCM has gone bad. Your fan should come on when you pull that connector. I wonder if anyone can explain why that wouldn't come on when the connector is pulled.

Maybe you can find a used one on here for your car?

I just chased a cooling issue in an 89 I'm working on. The system wasn't holding pressure (bad crimp on hose). Once I fixed that I allowed it to get to normal temp and verified the fan came on. I was relieved when I heard it spin up.
 
i figure the relays are working and getting power due to cutting #14 and getting low speed fan. Seems like I am missing some input to the IRCM post ECT or its getting an input and not translating that to an output.
I purchased an EEC IV analyzer off ebay so I should be able to do some more testing when I get it.
 
I think you are correct ... at least the low speed relay seems to be working, since you were able to turn on the fan by cutting the wire.

My guess would be that the ECM is not getting any information from the ECT sensor. Maybe a loose connection somewhere?

Have you scanned the codes? I wonder if you might have an "ECT out of range" code. (Of course, you would need to clear any codes caused by unplugging the ECT first. :rolleyes:)
 
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