Blows fuse #24 30amp

Tiny
4BOB
  • MEMBER
  • 1997 FORD F-150
  • 4.2L
  • 6 CYL
  • 4WD
  • MANUAL
  • 170,000 MILES
When you turn the key on. Found and taped up bare wires on passenger side where they got onto the manifold but still blows fuse #24. Any ideas on what to do?
Saturday, January 16th, 2016 AT 9:34 AM

4 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,408 POSTS
A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.
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Saturday, January 16th, 2016 AT 9:39 AM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
To add to Doc's answer, if those wires were shorted against the manifold, that probably caused wires from that circuit further down the line to melt together so you have only found part of the damage.
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Saturday, January 16th, 2016 AT 9:55 AM
Tiny
4BOB
  • MEMBER
  • 11 POSTS
If I unplug the wire harness from the pcm and test each wire will I be able to confirm or rule out the short being in those wires?
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Saturday, January 16th, 2016 AT 2:24 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,408 POSTS
As long as it' s not an intermittent problem. That is the REAL long way of diagnosing a problem. You wouldn' t want to pay a mechanic to troubleshoot a problem this way. What are you trying to solve?
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Saturday, January 16th, 2016 AT 2:54 PM

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