WHAT WOULD CAUSE NO PCM GROUND SIGNAL TO AC RELAY IN BATTERY JUNCTION BOX

  • Tiny
  • brianharris
  • 2005 Ford Taurus
  • 11,500 miles

Hi I am hoping I can get some help and do appreciate all and any help. I just put a motor in a 2005 ford taurus 3.0 ohv it went smoothly and had no problems runs great and cooling fans operate it was a used very complete engine swap 15,000 miles on used motor this motor did come with complete engine harness I have studied my schematics and cant come up with an answer ac low side switch has power across red and purple wires to ac over presssure switch which turns into a green with white tracer wire that goes to pcm I have ohmed out this wire in harness to pcm no problem also I went to ac relay missing ground from pcm to trigger relay it is a pink wire which I also ohmed out in harness if this wire is grouned ac will engage this is a manual ac system I was dumb enough to install my scanner to check bcm codes but there was no options cause its manaul ac I guess

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Friday, May 25th, 2012 AT 1:17 AM

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  • Tiny
  • ASEMaster6371
  • Expert
  • 25,556 posts

Needs to see the signal from the control head, needs to see a signal from the high pressure switch and the tps voltage cannot be at 4.8 volts.

If all these are ok, it may be a failed pcm.

Roy

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Friday, May 25th, 2012 AT 1:28 AM

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