Sold - IRCM, used, '93

KMT

Registered User
Sold IRCM - used, came off a wreck in 2015, untested, told it fits a ’93 SC. P/N F1SF-12B577-AA ‘L'
 

Attachments

  • IMG_6153.jpg
    IMG_6153.jpg
    47.7 KB · Views: 140
Last edited:
Would this work for any 89-93 SC? I have seen elsewhere that 93/94 is when some sort of change occurred.

What do the differences in part number mean? I have an 89 5-spd. Mine has gone bad and has part number E9SZ 12B577 A. Can I swap in this one?

Are bad units repairable? I'm wondering if after swapping in a replacement I can take my bad unit and eventually get it repaired to have on hand for future need.

Thanks,
MP
 
Thanks for the pointer to info on repair & troubleshooting. I obviously didn't look deep enough through the IRCM related threads I found.

The symptoms are the fan doesn't come on when the car is idling or at low speed. I have not had a warning light come on, but the gauge has been near red at low speed driving. It immediately cooled off when I got up to highway speeds and stayed cool until I hit traffic/stoplights. In hindsight, the first indication was what smelled like burning coolant when I would park the car in the garage, but I never found a leak or noted a high temp.

The shop I took it to tells me the unit tests bad, with the rest of the circuit and fan showing normal. The fan is just a couple years old with about 4k miles. I have already found an IRCM through TBSC Shop so I intend to swap it out. Then I'll see if I can rebuild this one using the info you pointed out for me. I'm not very mechanical, but willing to try when I find good directions.

If yours becomes available I would still be willing to buy it. I read another thread where someone claimed to have several on the shelf for when his inevitably died. It seems like a prudent course of action when feasible. Just wish I could find some shocks to put on the shelf.

Thanks,
MP
 
If you have a code reader, hook it up, key on, engine off, then initiate a self-test. I'd be interested to know if the fan spins up as a result. Go ahead and run at least a full KOEO test to see if any codes come back, posting them here, thanks.

Ken
 
Last edited:
Thanks, especially since I've now learned the SC is an ODB 1 vehicle and I don't have the correct scanner. Of course the port location is not where the one posted picture I found showed it, but I see it back near the passenger side firewall. There are two ports; EEC test & ARC/EVO test. I believe I need the EEC port for this check.

I'll get the correct scanner and get back to you.

MP
 
I see it back near the passenger side firewall. There are two ports; EEC test & ARC/EVO test. I believe I need the EEC port for this check.

That's the one.

And note there are ways to manually test by grounding a couple wires at the IRCM connector, but I've come to rely on a self-test via code reader, instead. I think you'll find an OBD-I reader very handy. I'd be on the lookout for these codes as well as when using the code reader: 83 / 88. Doing both KOEO & KOER would be good, but if the fan doesn't come on w/KOEO, I'd hate to see you risk running the car hot so you can do a proper KOER if the fan isn't working, so be careful.

The checks the shop did may have already answered the question, but doing a self-test can help confirm.

This list of codes calls out those specific to the SC: http://www.njtacc.com/tech/eec_codes.html

About your '89 and which IRCMs fit... I've heard that some early SCs have a road speed cut-out relay right near the two test port connectors you found. There is a circuit that shuts off the fan above 40 mph(?), and on later years, that relay is in the IRCM. If you can dig around in that location and count the relays, I think later have two (ABS related) and if there is a 3rd one in the bunch, it's the A/C cut-out. I've no idea if that means you need a an (early) '89 IRCM, or if they even exist. Do your know the part number on yours?
 
Last edited:
I ran the KOEO test. The fan came on and the codes 21, 24, & 67 came back. I ran it twice and 67 only came back the second time.

I rant the KOER test and code 21 came up. That's "Coolant Temperature Sensor (CTS) out of range". I'm assuming that's a problem with the thermostat.

Now I'm wondering why my shop is telling me it's the IRCM.

Thoughts?

MP
 
21 means ECT (same as CTS) - that's the 'engine coolant temp' sensor that sits on top the engine, front pass. side, behind the A/C compressor. Sits vertical w/the connector facing down onto the sensor.

Was the engine warmed up, say at least 5 minutes, preferably more, when you did that test?

If the ECT failed outright I'd expect other codes and a check engine light.

Try one more test..with the engine running, pull the connector on the ECT sensor and see if the fan runs. It should.

If you have the ability to backprobe and test with a digital volt meter at the ECT sensor's connector, I can explain how to check it live.

Any idea how old the thermostat may be? Warm the engine up and feel the housing to see if you can tell when it opens (pain is 140°, so it should be around that in a few minutes, and then jump as the engine heats up and the stat goes open). An IR temp gun can help check it as well. If it's stuck open, the engine would take it's time warming up properly until it's under load. The fan would eventually work, tho, when conditions were right, if the ECT was good.

Since the KOEO test triggered the fan, that validates the ECU's trigger circuit, the IRCM's relays and it's wiring, and the fan and it's wiring.

I'd want to check the harness/connector at the ECT, and consider replacing it. I'd also want to know more about what's happening with the thermostat. Finally I'd want to be sure there isn't air in the cooling system. An air pocket at the ECT can mess with it's readings.

What kind of action are you seeing on the temp gauge in the dash?
 
When I remove the ECT connector, the fan runs and the check engine light comes on.

The engine was just warmed up about 3-5 minutes before the KOER test. It was just slowly coming up off the 'blue' when I did the test.

Not sure how to test the ECT connector. I put my multi-meter on it and read 4.63V at the connectors.

The gauge seems to stay on the low side of normal when I'm at 40 and above. Driving it home, it climbed slowly to the middle of normal at the stoplight then dropped quickly back down one I got up to speed for a couple of minutes.

The only thing recently that has happened with the cooling system is the bolts on the water pump pulley backed out and I ended up eating the serpentine belt. The shop replace the bolts and the belt, but I don't know if they emptied or refilled the coolant.

While idling, the temp came up to the 'O' on the gauge. I pulled the ECT connector to run the fan and the temp came down to the low side of normal.

MP
 
One more test I think was overlooked, sorry - w/engine running, does the fan run when you turn on the A/C?

Also has the temp ever gone beyond R on the gauge?

When idling and hitting O, does the temp stay there and then fan not run now?

BTW, the 4.x volts across the ECT connector pins is just signal. Just means the ECU feed is ok. If you can't get into the wires to test live when connected, you may need to throw a new ECT in to know for sure.

ECT testing goes like this...

LG/Y is signal out at ECT. This goes to EEC. Backprobe it to check when engine runs and heats up. Ground black lead off meter to complete circuit to test. If meter does not auto range, be sure to use lower scale to read DC 5v and less.

The low speed fan comes on at 0.37v coming out of the ECT, at it's connector. Must be above 50° ambient

• 0.60v = 194°, below N on the gauge, stock thermostat is full open @ 192° ~ 195° depending which is installed. My SC has a 192° stat as of 2.15.19 that went in back in 2017.
• 0.53v = 200°~ 205° and N on the gauge
• 0.46 left side of O, 212~215°
• 0.42 almost straight up O ~ R, 218°?
• 0.37/.39 220°~222° low speed fan turn on, left side of R on gauge
• Fan comes on and drives it back to N +/- depending on load and ambient air temp, etc.

Notes:
  • lo speed on at 222° and above / off at 214°
  • hi speed on at 228° and above / off at 220° …if hi is on, it will drive temp down and shut off at 220°... lo will also still be on, pushing temp down to 214, then fan is all off.
  • A/C on runs lo speed fan, not hi.

At this point,-if- there is a problem, and it's electrical, I'd bet on it being the ECT sensor. and/or harness~connector issues. If it's mechanical, I'd guess air in the system, could be a one time thing, or there could be something going on, such as headgaskets, water pump sucking air/worn out, bad thermostat, dirty radiator, etc. I'm not sure you have an issue just yet, but I'll wait for answers to the 3 questions above.

Ken
 
Last edited:
I appreciate the patient advice.

The fan does come on when I start the AC.

I don't think the temp ever went red, but the day the belt came off I pulled to the side of the road and inspected under the hood without shutting down the engine. I then had to pull another 50 feet off the road and the radiator cap was starting to sputter coolant. I remember the gauge being at the max normal and rising.

When idling, the temp rises until about halfway between "L" and max of the normal range. Then the fan kicks in and drops the temp just below "O" and then shuts off. The engine strained a bit when the fan kicked in but smoothed quickly.

A new aluminum radiator was installed before I bought the car two years ago, so I doubt it's dirty.

I went for a drive mixing some stoplight traffic with mostly country roads and some freeway. The temp seemed to run higher than I remembered for normal driving, but never went past "L" mostly staying at or below "O". It came down to low normal at speeds over 65.

So maybe I don't have a problem and was just surprised at the seemingly 'high normal' temp. But I had been smelling burned coolant when parking the car and had never noticed it get so warm. In the summer I usually run the AC. The "high temp" incident was in Dec.

But I'm getting a 21 code, so something is not right.

Do you think I need to swap out the ECT?

MP
 
I appreciate the patient advice.

Thank the forums for allowing us to troubleshoot via the 'parts for sale' forum ;)

The fan does come on when I start the AC.

That's good news and would, in my opinion, validate everything else electrical outside the ECT & it's connector.

When idling, the temp rises until about halfway between "L" and max of the normal range. Then the fan kicks in and drops the temp just below "O" and then shuts off. The engine strained a bit when the fan kicked in but smoothed quickly.

I'm a bit confused - I thought the SC temp gauge used 'C' 'NORM 'H'. I'm sure we're on the same page, just haven't seen a cluster like you describe.

But I'm getting a 21 code, so something is not right. Do you think I need to swap out the ECT?

If you can't test it live easy enough, sure, so go for it. Less than $20, IIRC. Pull codes again when it's in to confirm. Might want to also throw a new radiator cap on it, straight 16#, if that one is years old. Don't forget the issues related to air in the system, search/speak up if you need details on dealing.

Good luck.

Ken
 
Thanks. In my initial replies I didn't even realize it was the parts for sale forum. I found you in the new posts section, which is where I usually start just to see what people are working on. Then it just turned into a conversation.

I'll look at a new radiator cap, but the whole radiator is only 3-4 years old.

Yes, the gauge reads "NORM", not sure why I was thinking otherwise when I posted.

Thanks again.

MP
 
Back
Top