Mechanics

FORD F-150 FUSE PROBLEM

1997 Ford F-150 • 20,000 miles

I driving and my truck just cut out. It cranks no spark no fuel pressure, pump doesnt prime.I dropped the tank thinking it was the pump, bench tested the pump it was good. Before that I did check fuel pump fuse under dash fuse for fuel pump under hood. The relay iswitched with others, they all click.I realized the PCM fuse was blowing when I put the key in the 2cnd position. Checked all the wires to pump o2 sensors. After reading up on it, looked for hours for trouble with wiring all looks good.I tried a test with a circuit light on the negative terminal of the battery with the cable off and the light hooked inbetween. The light stayed lit while I pulled every fuse until I pulled the GEM under the dash it went out. Turned key the pcm blows instant. Any knowledge of this problem will help thank you.
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Guest
January 18, 2013.




You have a short somewhere. Dis connect the pcm first to see if the fuse still blows. It if does, the issue could be a harness issues rubbing through and shorting out. It could be anywhere. Wiring issues are time consuming.

If it does not blow the fuse, it may be an internal short in the pcm

Roy

ASEMaster6371
Jan 18, 2013.


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