Anti theft not communicating with PCM?

Tiny
DAVIDNUNNALLY
  • MEMBER
  • 2006 FORD F-150
  • 4.2L
  • V6
  • 2WD
  • AUTOMATIC
  • 261,000 MILES
Hello,
I have been hard at work all day trying to confirm whether or not the problem is in the PCM, or the fuse box. I would like a pin-out so I can check those plugs into the PCM from the fuse box and know what should be power going to the PCM. Ultimately, I'm not getting power from the module near the spare tire to the fuel pump. Then at some point the anti-theft system locked out anything else happening. The light doesn't even come on when you turn the key. The dash says "check gauges." Also, the OBD port is down. All the fuses check out good and I know I'm getting power to some of the pins at the PCM.
thanks,
David
PS. I do have access to the shop manual pinouts but what I'm finding is different than what is shown there.
Thursday, April 10th, 2025 AT 8:48 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Sure, I have seen this problem before, the CJB goes out due to water damage because of its location. I would remove it to help confirm the issue. If you do not have power going to the fuse: f41 and fuse f5 the panel, it is bad and needs replacement.

This guide can help:

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

If you have power to fuse #f2 then you know the fuse panel is getting power from the battery and the panel is to blame. Please go over this guide and get back to us.

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Friday, April 11th, 2025 AT 11:58 AM
Tiny
DAVIDNUNNALLY
  • MEMBER
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Somehow I did not see the reply. Thank you for the reply! Since I wrote this, I have confirmed that there is no ground going to the PCM relay which in turn powers fuses 32, 33 and 34. When I put a good ground to the ground wire from the PCM to that relay I had power at the fuses above. So with the help of a local friend, we have determined the PCM needs to be replaced. Please see picture. However, I would welcome any comments.
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Wednesday, April 16th, 2025 AT 7:47 PM
Tiny
KEN L
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  • 54,137 POSTS
Can I ask where you got this wiring diagram from? Yes, if the PCM is not grounding the relay then power will not be transferred. I would replace the PCM which should fix it.
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Thursday, April 17th, 2025 AT 9:42 AM
Tiny
DAVIDNUNNALLY
  • MEMBER
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Here is the link to the site I found the wiring diagram. https://www.ford-trucks.com/forums/1539213-2004-2008-f150-wiring-schematic.html

I ordered a pcm and will report back on how that goes. Thanks for you help. David
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Thursday, April 17th, 2025 AT 2:22 PM
Tiny
KEN L
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  • 54,137 POSTS
Sounds good thanks for the info! Let me know how it goes.
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Saturday, April 19th, 2025 AT 9:11 AM

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