fuse keeps blowing
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fuse keeps blowing
The 15 amp fuse (#14 in my 99 Expedition) blows with a blue spark each time I try to replace the fuse. Power windows, interior lights, running board lights, rear wiper did not work several weeks ago. Checked the fuse and it was blown. Replaced and all ok (except rear wiper works when it wants to) until several weeks later (today). Noticed same thing again and replaced fuse to find that it blew the instant I replaced it.
No loose wires in rear door (around the wiper motor), all interior light bulbs seem to be ok (no fusion around bulbs).
Fuse in the fuse box under the hood seem to be ok. Only the fuse under the dash seems to be affected. Small bit of corrosion around negative battery terminal but no other electrical problems.
Any ideas anyone?
No loose wires in rear door (around the wiper motor), all interior light bulbs seem to be ok (no fusion around bulbs).
Fuse in the fuse box under the hood seem to be ok. Only the fuse under the dash seems to be affected. Small bit of corrosion around negative battery terminal but no other electrical problems.
Any ideas anyone?
Post Fiend
Joined: Apr 2002
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From: Central Kali
Hi and welcome to FTE! 
A wiring diagram would be a big help. Assuming the fuse controls the stuff that quit working before, I would look at the same stuff. Can you unplug the wires going into the doors?
Sometimes you just have to start isolating circuits to find the one causing the short circuit. Let us know what you find.
A wiring diagram would be a big help. Assuming the fuse controls the stuff that quit working before, I would look at the same stuff. Can you unplug the wires going into the doors?
Sometimes you just have to start isolating circuits to find the one causing the short circuit. Let us know what you find.
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Thanks Mike,
What is a "wiring diagram" and what would I do with it when I get it?
This fuse does control all mentioned (windows, interior lights, running board lights and rear wiper). I disonnected wires to rear wiper, disconnected interior lights, under the hood light and it still blows. Could not get to the running board lights. The windows and wiper are not pulling any amps when I try to replace fuse. The only things that are trying to come on are the lights (truck is off and key is out of ignition)
What is a "wiring diagram" and what would I do with it when I get it?
This fuse does control all mentioned (windows, interior lights, running board lights and rear wiper). I disonnected wires to rear wiper, disconnected interior lights, under the hood light and it still blows. Could not get to the running board lights. The windows and wiper are not pulling any amps when I try to replace fuse. The only things that are trying to come on are the lights (truck is off and key is out of ignition)
Moderator
Joined: Jan 2001
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From: Virginia
If the running boards were added on and not from the factory, I would be suspicious of the wiring. Not everybody takes care when wiring something up on their vehicle.
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Finally got a chance to "work on it" some more. Trial and error has shown me that replacing the fuse with all doors closed, everything works fine. The minute I open ANY door, the fuse blows. With doors closed, I can turn on every light I can find, and no problem, but when I open ANY door, the fuse blows immediately. I have tried it with key in and with key out. I dont think it is the "dinger" that lets me know lights are on, etc.
I have repeated all steps with running board lights disconnected, and all interior lights disconnected.
I am afraid to become the next victim of a visit to Ford Service Dept. to hear "I am sorry, but we could not find anything wrong"
I have repeated all steps with running board lights disconnected, and all interior lights disconnected.
I am afraid to become the next victim of a visit to Ford Service Dept. to hear "I am sorry, but we could not find anything wrong"
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From: Virginia
It looks like your dome lamp circuit has a problem. You said you unplugged the running board lamps. If these were aftermarket, I wonder where they got their power from? If you unplugged the board's wiring right at the running boards, I wonder if the problem could be up the line a little where possibly the wire runs through into the interior?
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I dont think problem is with running boards. The running boards were factory installs.
Fuse doesnt blow if I have interior lamp relay pulled.
It must be wiring.
If I want to start chasing wires, were do I get one of these "wiring diagrams" mentioned?
Thanks,
Fuse doesnt blow if I have interior lamp relay pulled.
It must be wiring.
If I want to start chasing wires, were do I get one of these "wiring diagrams" mentioned?
Thanks,
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From: Virginia
www.helminc.com is the best source.
You may try a Haynes manual. But I don't know if they have any for your model.
You may try a Haynes manual. But I don't know if they have any for your model.
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SOLVED (sort of)
Went to public library and found interior lighting wiring diagram in Mitchells Manual. With the help of my electrical engineer neighbor, we traced / trial & errored the problem to a light in one of the front doors - that only come on when the door is opened.
Couldnt get to the right wire behind the fuse box - after removing half of the dash. Discovered that by removing the "interior light" relay-all is ok. Except that the interior lights dont come on when the doors are opened. But now we can at least manually turn on the overhead map lights due to power reaching them thru another relay. And my wife is happy again because she can lower the windows at the bank drive-thru....
Thanks for the tip on getting the wiring diagram. Without that bit of knowledge, I would still be at square one. I didnt know those things existed and I now have a new use for our public library. Our library, as most I suppose, has access to Mitchells on-line since they subscribe to their manuals. Makes it really easy to get any repair info.
Went to public library and found interior lighting wiring diagram in Mitchells Manual. With the help of my electrical engineer neighbor, we traced / trial & errored the problem to a light in one of the front doors - that only come on when the door is opened.
Couldnt get to the right wire behind the fuse box - after removing half of the dash. Discovered that by removing the "interior light" relay-all is ok. Except that the interior lights dont come on when the doors are opened. But now we can at least manually turn on the overhead map lights due to power reaching them thru another relay. And my wife is happy again because she can lower the windows at the bank drive-thru....
Thanks for the tip on getting the wiring diagram. Without that bit of knowledge, I would still be at square one. I didnt know those things existed and I now have a new use for our public library. Our library, as most I suppose, has access to Mitchells on-line since they subscribe to their manuals. Makes it really easy to get any repair info.
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Mitchell website is www.ondemand5.com
It was much more indepth and thorough than Chiltons.
Ask your public library research center if they subscribe.
It was much more indepth and thorough than Chiltons.
Ask your public library research center if they subscribe.
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