PCM fuse?

27ANTHONY

MEMBER
1999 MERCURY MOUNTAINEER
5.0L
V8
AWD
AUTOMATIC
124,000 MILES

My 1999 Mercury Mountaineer will crank but not turn over, I did a light check on the PCM fuses under the hood and found that I'm not getting any power for the camshaft positioning sensor/EGR vacuum regulator/EVR solenoid/heated oxygen sensor. The fuse is not blown but replaced it anyways still nothing. Those anyone have an idea what could be wrong?

Saturday, July 4th, 2015 AT 11:11 PM

8 Replies

WRENCHTECH

MECHANIC
20,761 POSTS

Yes the PCM (f1-15) fuse can cause this issue here is a guide to help you test for power and the fuse location below.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Images (Click to make bigger)

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Sunday, July 5th, 2015 AT 6:03 AM

SAM.SMALL

MEMBER
2 POSTS

Thanks for this post I had this problem and it was the fuse.

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Thursday, December 27th, 2018 AT 9:01 PM

FILMBOSS

MEMBER
10 POSTS
2002 MERCURY MOUNTAINEER
125,000 MILES

I have an odd question. I have a 2002 Mercury Mountaineer, runs great. But lately, my windshield wipers have been acting up. When I first start the car, they don't work. However, after the car has been running about 10 minutes, they work, but only at a couple different speeds. Once I stop the engine for a while, then restart it, the same problem with the wipers. Is this a simple fuse or does this have something bigger attached? Everything else electrical in the car works fine, only the wipers. Any ideas? Could this be the cpu? Or epu? (Sorry, I forget what you guys call it, the brain of the car's computer). If it was that, wouldn't other systems on the car be starting to fail? Please help.

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Friday, December 28th, 2018 AT 9:39 AM (Merged)

DRCRANKNWRENCH

MECHANIC
3,380 POSTS

There are 2 things that could be happening. There is a wiper control board for the intermin=tant function which may be failing. If you find you later have trouble with the high or low speeds that are not intermitant then the multi function switch is bad.

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Friday, December 28th, 2018 AT 9:39 AM (Merged)

FILMBOSS

MEMBER
10 POSTS

That is what's happening already. When the wipers come on, they are only on a regular speed. Intermittant fast or slow no longer work. Ford dealership service rep, who I'm assuming was trying to upsale, said it's most likely the cpu/epu (computer brain) is going bad and I should replace that. It's a $850 part! He never mentioned the wiper control. Is there a way I could check that out? How much to fix something like that? Could the Ford Dealership be correct? But if the cpu/epu was going bad, wouldn't other systems in my car be failing as well?

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Friday, December 28th, 2018 AT 9:39 AM (Merged)

DRCRANKNWRENCH

MECHANIC
3,380 POSTS

The wiper control board is almost always a separate PCU unit separate from the ECU. I am attaching the wiring diagram that shows the control board is a solid state unit that is part of the wiper motor. If you will notice the multi-function switch has intervals for different intermittent speeds. They all lead to the solid state controller board. The high and low speed are simply controlled by relays in the wiper motors as they are a constant on function. So, the ECU is not involved. You need to get a new wiper motor which will have a new control board in it. I would look for a re-man. You should try www. Rockauto. Com as they have the best prices and name brands on re-maned and even new parts.

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Friday, December 28th, 2018 AT 9:39 AM (Merged)

FILMBOSS