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Check engine - crank position system error

Tiny
05EXCURSION
  • MEMBER
  • 2005 FORD EXCURSION
  • 0.5L
  • V10
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
In 2015, we took our car into Ford for the "check engine light." The mechanic did not believe it was this (error code for crank position system) since our vehicle runs like a top. So, we had a "refurbished, " PCM in case the old one was pushing out wrong codes. Then, the following day we noticed now the "anti-theft light" was flashing. So, we took it back in. We have had the PCM replaced many times, and just had the original placed back in. There are no symptoms of the crank positioning system. We do notice the A/C is not as cool as our Honda Odyssey, but no other problems.

My husband was thinking of way to bypass the PCM altogether. We are just scratching our heads. Yes, we did take it to Ford and had it serviced. Any suggestions would be most appreciated.
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Sunday, September 3rd, 2017 AT 9:44 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,960 POSTS
No possible way to bypass the PCM, it controls the engine and transmission and more. The error was likely the crank position sensor. That could be a simple wiring problem or a failing sensor. I doubt its' a false code.
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Tuesday, September 5th, 2017 AT 9:46 AM
Tiny
05EXCURSION
  • MEMBER
  • 2 POSTS
The sensor and pigtail wiring has been replaced by the Ford service dept. We've gone through 4 PCM's.
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Tuesday, September 5th, 2017 AT 7:22 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,960 POSTS
The end by the sensor has been replaced. That doesn't rule out the rest of the harness. It would depend on what the sensor is actually doing and what the code is.
That sensor is a simple item, tossing a scope on it and comparing it to a known good waveform would enable it to be ruled out, or it may show interference from something the wiring is routed near, that is supposed to be a shielded wire to stop that but if the shielding is bad it could get a signal that is wrong.

4 pcms throwing the same error rules out it being the PCM. BUT it doesn't rule out the PCM getting bad data from the sensors and wiring.

What were you doing when the light first came on?
Can you get the exact code(s) it is showing?
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Tuesday, September 5th, 2017 AT 11:37 PM

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