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Thread: Radiator fans with egnition off?

  1. #1
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    Radiator fans with egnition off?

    After getting my 91' SC running outstanding I now have this issue that just started today. I had to disconnect the fan motor so my battery wouldn't go dead. I have replaced so many parts so I have no clue what's causing this.

    Can anyone please give me some ideas?

  2. #2
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    when my car did that i noticed the small ground wire from the battery to the fender was loose , i added an extra wire to be sure and never had an issue again

  3. #3
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    Bad IRCM is the only thing that can turn the fan on with the key off.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  4. #4
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    Is the IRCM the box located in front of the air filter?

  5. #5
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    Quote Originally Posted by Coroner View Post
    Is the IRCM the box located in front of the air filter?
    Yes.

    Can you be 100% clear on when the fan runs? Does it run with the car turned off, you standing in front of the hood with the key in your pocket?
    God bless!!!

    1990 SC auto ... red outside, gray cloth inside ... ~205,000 miles (and climbing) ... driven daily!

  6. #6
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    Quote Originally Posted by S_Mazza View Post
    Yes.

    Can you be 100% clear on when the fan runs? Does it run with the car turned off, you standing in front of the hood with the key in your pocket?
    Yes. It started doing it when I returned to me car after shopping and noticed the fan was still running by it's self.

  7. #7
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    Gotcha. It wouldn't be the EEC ground, then. I guess the IRCM is the place to look, as Dave suggested. Probably, one of the relays inside welded closed.

    You can get a rebuilt box (expensive) or test and replace specific components yourself if you are comfortable with it. You will have to drill out a couple of rivets to open it.
    God bless!!!

    1990 SC auto ... red outside, gray cloth inside ... ~205,000 miles (and climbing) ... driven daily!

  8. #8
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    I had replaced the IRCM with one from the bone yard in an attempt to get the temperature to run with the needle straight up rather then pointing at the M all the time but I remembered to save my original so I switched it back and all is good except for the fact that the temp gauge still remains pointing at the M which I still can't figure out.

    Anyone have any ideas as to what could be done to lower the temperature so the gauge stays straight up instead of pointed to the M?

  9. #9
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    The IRCM doesn't dictate the temp the engine runs at, that is determined by the rest of the cooling system and the EEC. If you have changed the thermostat to a lower temperature without also getting a chip to command the fan on at a lower temperature then the engine will run hotter.

    If you haven't done that, then make sure the fan is working on both speeds. 220 deg for the low speed, 228 for the high. The M usually coincides with close to the 228 deg. It could well be that your low speed fan isn't working.

    Otherwise, clogged radiator, leaking headgaskets, air pockets, etc. are all things that can cause a hot running engine. Check the fan operation first.
    Last edited by XR7 Dave; 06-13-2014 at 08:20 AM.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  10. #10
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    Coroner - one thing to keep in mind is that there are TSBs on the sending units being bad.

    Have you queried the ECU to see what temp it thinks you're at? M may be, say, 200F ...

    RwP

  11. #11
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    Quote Originally Posted by RalphP View Post
    Coroner - one thing to keep in mind is that there are TSBs on the sending units being bad.

    Have you queried the ECU to see what temp it thinks you're at? M may be, say, 200F ...

    RwP
    No I haven't. I do have a new fan motor and both speeds do work. Low when the air conditioning is on and high when it get up to full temperature. I installed a while back with a standard thermostat.

    So how do I querie the ECU?

  12. #12
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    both my sc always ran fairly cool unless a lot of city driving or a bad thermostat or headgasket or clogged radiator

  13. #13
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    180 t-stat

    I changed my t-stat in my 93 sc a few months ago (180) so mines is running a lil high now. I was told I need a tune to tell my eec to turn the fans on sooner. where can I get this (tune or chip)........I forgot to ask the guys ,damion dave while I was at carlyles last weekend.

  14. #14
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    Quote Originally Posted by pock1 View Post
    I was told I need a tune to tell my eec to turn the fans on sooner. where can I get this (tune or chip).
    This sounds like just what I need. Anyone know how to do this?

  15. #15
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    Quote Originally Posted by pock1 View Post
    I was told I need a tune to tell my eec to turn the fans on sooner. where can I get this (tune or chip)
    So is this even possible????

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