Engine fan speed issue (low speed)

Discussion in 'General Tech' started by Blackstang, Jun 15, 2020.

  1. Blackstang

    Blackstang New Member

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    Hi
    I have an issue with my engine fan, low speed does not come on on my 1994 GT 5.0 causing my engine running very hot and I have done my homework and searched the net for information. High speed works (but as you know it comes in very late and does not run for long) and also in A/C mode at any temp, then with A/C temp goes to normal but that is not how it should be.
    What i have done and checked so far.
    • Fuse OK
    • Temperature sensor for fan replaced (Motocraft)
    • Measure pin 14 on CCRM no power when temp goes high
    • Direct power (override) to fan OK
    • Override pin 14 with cable from battery ; fan works CCRM OK
    • Checked for Oxide on PCM cale socket, no problem but cleaned up anyway
    • It is hard to measure on PCM but most likely there is no power from pin 55

    My conclusion is that the problem is inside the PCM but I have not found anywhere the PCM could cause fan issues, but theoretically it could I suppose. Anyone have had this problem? I can change the PCM if I have to but would like to be pretty sure that this is the problem coz it is expensive. Can also mentioned that the radiator have been replaced but I am confident that there are no air pockets left in general but could I have caused an air pocket at the temperature sensor when changed?

    Preferably I would not like to mount a manual fan swith but if that is the last option, I could do so.

    Should I do a KOEO test? I red about it but has never done it. Could it be an air pocket at the temperature sensor? Could a ford dealer measure anything from the diagnose socket? Like the signal from the temp sensor? All help would be appreciated.

    Best Regards from Sweden
     
  2. BigBore96

    BigBore96 Active Member

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    Im not much help with narrowing down wiring issues but Have you considered having the high speed fan on anytime the key is on?

    It's very easy to do by just grounding it down near the ecu. If interested I can probably find a write up somewhere.



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  3. Blackstang

    Blackstang New Member

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    Thanks for your reply, maybe it could be an alternative for sure. Better than a manual switch in my opinion. If you find a write up or something it would be appreciated.
     
  4. BigBore96

    BigBore96 Active Member

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    Here it is. Link is to the thread on this forum.

    First post is for the 94/95s
    https://www.sn95forums.com/threads/how-to-manually-turn-on-your-fan.7232/


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  5. Blackstang

    Blackstang New Member

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  6. ttocs

    ttocs Legend

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    which fuse did you check?
     
  7. BigBore96

    BigBore96 Active Member

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    No problem.

    Something else to easily check. Unplug the fan and inspect the connector. I've seen one side or the other melt and fail.

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  8. Blackstang

    Blackstang New Member

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    I checked the 60 Amp fuse in the fuse box in engine compartment, but high speed is working.
     
  9. Blackstang

    Blackstang New Member

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    Thanks, I checked the connector and low speed works if I put direct power pin 14 on CCRM(signal cable from PCM to activate low speed) that signal is missing from PCM. So should be cable failure or PCM in my opinion.
     
  10. ttocs

    ttocs Legend

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    just to be stupid check ALL the fuses big and little. You will find it only takes about 2-3 mins, less time than it takes to find the correct page on fuses in the manual and then you can be sure they are all good. You would be surprised how often you can find a fuse that seems to have nothing to do with the problem at hand but it was the problem.
     
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  11. Blackstang

    Blackstang New Member

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    Yes why not, easy check will do so. Sometimes the easy checks are forgotten.