MKX03 Posted February 20, 2019 Report Share Posted February 20, 2019 (edited) My 2008 MKX (spare vehicle) was overheating. I have been working on getting this fixed for a while After the first over-heat, I noticed the cooling fans were not coming on - even with AC on full blast. So I test the fans direct to 12V and they both work. Both 40 amp fuses are good. I know the fan control modules are a common issue so I concluded the FCM was dead and ordered a complete unit (2 fans, radiator and FCM). I live on a small island and parts take a while to get here so in the meantime, I wired the cooling fans to some relay's and switches so I can still drive it while I wait..I received the parts and installed them - the first test I did was turn the A/C to max and to my disappointment, the fans didn't turn on. (damn) So then I test the new fans direct to 12V and they both worked. And this is where I am now... At this point all I can think of is the signal wire from the FCM must not be getting power- so I check for continuity, At the PCM, i see that pin #48 is the wire I need to check (apparently the 3rd pin over from the right) according to this video - (fast forward to 16:20 mins) - https://www.youtube.com/watch?v=pXqpZoFxrbs I test that pin with the signal wire on the FCM plug harness - like he did but there doesn't seem to be continuity. So I further test - I open the wiring harness a little left to the PCM and find the white /BLU wire. And test that for continuity to the PCM #48 and it is good. Then I test at the FCM harness end - I find a white/BLU wire a few inches away from the plug and test that for continuity with the signal wire on the harness - and it is good. But when I test for continuity using the white wire a few inches from the PCM and the white wire near the FCM module harness, there is no continuity. So either it is not the same white/blue wire or there is a break in the wire.Final test - I tested the white/blu wire near the PCM (pin #48 according to the above video) for voltage and I get under 1 volt (even with A/C on full) - I understand it is variable. And when I test for voltage on the White/blu wire near the FCM harness, I get a different reading. 0 if the harness is not plugged into the FCM - but I get 12 or 13V when the harness is plugged into the FCM. So i am left a little puzzled... Edited February 20, 2019 by MKX03 1 Quote Link to comment Share on other sites More sharing options...
WWWPerfA_ZN0W Posted February 21, 2019 Report Share Posted February 21, 2019 First, did you install Motorcraft brand or some other brand. Anything but Motorcraft can end up failing on you soon, or sooner at least. I assume a new module was included with the new fans? Tried using the OEM module with the new fans? Quote Link to comment Share on other sites More sharing options...
Omardottcom Posted November 1, 2022 Report Share Posted November 1, 2022 MKX03,….. Did you ever figure out what the problem was? I’m currently chasing this same issue. I could really use your help/experience. Thanks. Quote Link to comment Share on other sites More sharing options...
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