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Discussion Starter · #1 ·
Looking for a second opinion. As I posted before my car died while driving on the highway about 3 weeks ago. When I got it home I had no communication with the scanner to the PCM, my cooling fans were stuck running on low speed, and instead of the fuel pump priming the system, it wouldn't shut off.

I've had very little time to look into this over the last 3 weeks. But last weekend I managed to check out the CCRM and visually inspect the wiring harness for any signs of chaffing. Both checked out fine. Today I double checked the CCRM just to be certain. I checked out the harness this time using my multi-meter to check to continuity from one circuit to another. (ie: checked fuel pump circuit for continuity and then checked other pins on the connector for any signs of readings. Everything checked out fine. So I'm left now believing the PCM is my problem and needs to be replaced. I would like to know before going to buy a replacement if there is anything else I could be checking. I don't believe there is any way to check the PCM other then swapping it with another.
 

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I assume you've checked the fuse to the dlc? Make sure there is power on both sides with a test light. Fuse 30, 15amp under the dash. Actually, the horn relay is on the same fuse, so just try to beep the horn.

The PCM Power relay controls the fans and the fuel pump, so check that. Either test it if you know or switch it with a known good relay of the same type, making sure you're not taking out something necessary. This relay is in the fuse box under the hood. There is a red wire that goes from the fuse box to the relay center, make sure when the relay is pulled there is no power at the red wire when the key is turned to start.

If the pcm power relay is sticking, the fans will always run and the fuel pump will keep cycling. If there is power to the relay center with the relay out, there is a power short doing the same thing.
 

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Discussion Starter · #4 ·
I did check all fuses, all are ok. As for the PCM relay and such, I cannot access them as they are in the CCRM. There is power to the CCRM, checked grounds on the PCM, everything so far checked out good. Only thing I can do I guess is try a different CCRM from a donor car. Would an '05 be compatible with my CCRM? I have my doubts, but figured I'd ask anyway.
 

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Nonono. The pcm power relay is the FUSE BOX under the hood. Switch it out with the a/c relay or horn relay or whatever is the same type and see if that helps.
 

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It looks like the a/c clutch relay, which is right next to the pcm power relay, is the same type. Again,these are in the fuse box, not the relay center, under the hood.
 

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Discussion Starter · #8 ·
Well I ordered a PCM out of a junk yard with matching numbers. The dealer told me that they couldn't even order one as they are no longer available. Anyhew the replacement PCM arrived yesterday and today during lunch I installed it. I now have a running taurus again, and am so freaking happy about it. Not to mention being happy about being able to trace it down to the PCM.
 

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Good diagnosis. Glad to hear the car is up and running. Cooling fans constantly on, no scanner communication (If DLC is powered) and fuel pump running constantly are classic signs of a failed Ford PCM.
 

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that what i was saying if it was not the ccrm it had to be the pcm glad you tested it in stead of plug and throw out. all it took is varifing that the ccrm is good and the next step is the pcm like you did and btw good job!
 

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Thanks guys. Yeah I never just throw parts at a problem until I either look at it or I'm almost certain I know what the problem is.
if you want to amuse yourself, take the old PCM apart and look closely
at the solder joints on the bottom of the PC board. Bad solder joints could
have caused your issues...

bob
 

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Discussion Starter · #13 ·
^^^^I was thinking of throwing in the driveway so I could run it over everytime I went to work for the frustration that it cause me when it left me on the side of the road....lol

But I'll probably take it apart now that it's just a paperweight.
 
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