thedragonmas
join:2007-12-28
Albany, GA
| how to trace a short
1997 ford crown victoria
has suddenly developed a short odd thing. when you turn on the running lights (marker lights) the fuse blows, heres the odd part and leads me to believe the short is under the hood, ive sat there with those lights on a good ten minutes, then start the engine and with in a minute the fuse pop's
i do not have a test light but i do have a volt/ohm meter. so, whats the proper procedure for tracing a short? |
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3SGTE
ST215W
Premium,MVM
join:2000-11-23
there
clubs: | Does it have a trailer hitch?
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Striving for Parfection. |
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thedragonmas
join:2007-12-28
Albany, GA
| said by 3SGTE  :Does it have a trailer hitch? no, but i think i see where your going. could be the harness is there but the hitch just wasnt installed. |
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devnullgt
yep..I'm still alive
Premium
join:2000-11-06
King Of Prussia, PA | reply to thedragonmas
Ive used this guide before with my mustang: »mustangmonthly.automotive.com/80···dex.html |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs: | reply to thedragonmas
Is this a vehicle you have had for a while or is this something that you recently obtained? |
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thedragonmas
join:2007-12-28
Albany, GA
| said by Doctor Olds :Is this a vehicle you have had for a while or is this something that you recently obtained? about 2 years.
i should note what all goes out when the fuse blows, maker lights, tag light, instrument panel lights.
thanks. |
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sailor
Merry Whatever ..R.I.P. dadkins
Premium
join:2003-10-21
Long Island
1 edit | reply to thedragonmas
said by thedragonmas :said by 3SGTE :Does it have a trailer hitch? no, but i think i see where your going. could be the harness is there but the hitch just wasnt installed. Go down in the post to you see the one regarding trailer pigtail module 9th post down or so. ( its for a 99 Ranger but could be your problem as well )
»www.ford-forums.com/electrical-l···box.html |
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ironwalker
World Renowned
Premium,MVM
join:2001-08-31
Keansburg, NJ
clubs:
 ·Optimum Online
| reply to thedragonmas
How could a non used trailor hitch develope a short?
I'd check the basics first, water in any of the lamps, water in any of the bulb sockets,loose wires, rubbed bare wires.
Dime in the lighter 
Seriously, if the harness is tucked away nicely and hasnt moved since 97' and the harness has never been used, and the cap is over the connector tightly, its common sense that would be the last place the short would come from.
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| said by ironwalker :I'd check the basics first, water in any of the lamps, water in any of the bulb sockets,loose wires, rubbed bare wires. Dime in the lighter I either find a penny down in the lighter socket (if the owner has kids) or when I pull the lighter, the element is missing/parts of it is detached and you see that it is still down in the lighter socket causing the short from the way it is laying or has unrolled.
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thedragonmas
join:2007-12-28
Albany, GA | reply to ironwalker
no water, and i still dont get why i can set there with the lights on for ten minutes and have no problems untill i start the engine, then "pop" goes the fuse.... |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| What is on the same circuit/fuse that doesn't work until the key is on? Sometimes it is the lighter, did you check the socket out and look at the element?
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What’s the point of owning a supercar if you can’t scare yourself stupid from time to time? |
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Vamp
5c077
Premium
join:2003-01-28
MD
 ·Verizon FIOS
| reply to thedragonmas
said by thedragonmas :no water, and i still dont get why i can set there with the lights on for ten minutes and have no problems untill i start the engine, then "pop" goes the fuse.... Technically when the engine is running the fuse should be less likely to blow if it's a load issue, due to the higher volts (less amps) with alternator running. Unless you mean key on does it, then it's like said above probably something that turns on with the accessories.
Unrelated story: I had an interior lighting shorting problem that was random, sometimes a new fuse would instantly pop then sometimes it would be fine, but after a drive it would blow. I ended up removing both vanity mirrors, map light, and rear lights and pulling the wires out as far as I could, I pulled out like 3 feet of wire from the rear lights and it was a nicked wire from rubbing part of the roof that would short from bumps in the road/vibration, taped it up and never had a problem since.
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TheHarvester
Premium
join:2006-08-25
Dana Point, CA
| reply to thedragonmas
What fuse is blowing? A picture of the fuse box, fuse number. fuses protect multiple items and multiple fuses can protect one device.
For instance on your vehicle
Fuse #4 protects LIGHTING CONTROL MODULE and headlight dimmer.
fuse #6 protects Speed control, main light switch, headlight dimmer switch, LIGHTING CONTROL MODULE, clock and police power relay.
Fuse #8 protects LIGHTING CONTROL MODULE, power mirrors, Remote keyless entry,clock memory, radio memory, electronic automatic temp control, power seats, power windows and police spot lights.
As you can see it will help out greatly if we knew what fuse is blowing.
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THUD300
Part Of A Complete Breakfast
Premium
join:2002-06-07
Decatur, IL | reply to thedragonmas
Police or civilian version? |
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matt5
join:2001-10-06
Lagrangeville, NY
| reply to thedragonmas
Electrical sucks, shorts suck more. If it's happening when you are turning the vehicle on, I would lean towards it being a wire rubbing somewhere, might sound funny but shaking the car with her off, see if you can get it to pop.
Want to trace a short you do exactly what it sounds like, trace the wires. Get a wiring diagram and follow the wires everything on that fuse, from fuse to end, look for burned/bare spots. |
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thedragonmas
join:2007-12-28
Albany, GA
| reply to TheHarvester
said by TheHarvester :What fuse is blowing? A picture of the fuse box, fuse number. fuses protect multiple items and multiple fuses can protect one device. For instance on your vehicle Fuse #4 protects LIGHTING CONTROL MODULE and headlight dimmer. fuse #6 protects Speed control, main light switch, headlight dimmer switch, LIGHTING CONTROL MODULE, clock and police power relay. Fuse #8 protects LIGHTING CONTROL MODULE, power mirrors, Remote keyless entry,clock memory, radio memory, electronic automatic temp control, power seats, power windows and police spot lights. As you can see it will help out greatly if we knew what fuse is blowing. sorry about that, oversight on my part. fuse #4, im wondering if its the switch, no idea how id test that out tho.
said by THUD300 :Police or civilian version? police, got it at auction. when i had the panel off i noticed one of their wires, seems they didnt bother to tape it when they removed what ever it went to, wonder how many more wires are like that.
said by matt5 :Electrical sucks, shorts suck more. If it's happening when you are turning the vehicle on, I would lean towards it being a wire rubbing somewhere, might sound funny but shaking the car with her off, see if you can get it to pop. ironically one of the first things i tryd  |
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TheHarvester
Premium
join:2006-08-25
Dana Point, CA
| reply to thedragonmas
All this is assuming the vehicle is the 4.6L SOHC vin 6.
What is the 8th digit of your vin number. I don't think it will change things but it may.
Alldata doesn't show the current path through the lighting control module but it does show how it runs through the switch. Basically it goes from the fuse and splices off. One goes through the dimmer switch and then into the Lighting control module and the other goes into the lighting module.
one way of narrowing down things is to add a smaller amp rated fuse to each wire just before the component. install a 5-10 amp fuse in the White with purple tracer wire going into the headlight switch and a 5-10 amp fuse in the Tan with white tracer wire going into the lighting control module.
Depending on which fuse blows that will lead you into the specific direction. If the normal 15 amp fuse#4 blows then the problem is between the fuse and the components.
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StNickless
@tmodns.net
| Ya gotsta think a wee bit deeper on this one.
It probably had (or maybe even still has) a rapid flasher for the "wig-wag" lights the cops use.
I've seen many mods where they tie in with "scotch-loks" to connect those up.
Anything with a scotch-lok on it is PURE FAIL.
Even brand new those things just don't work.
Most cop cars have had a higher amperage alternator butchered into the system.
I have never seen a clean install of one, it is always butcher city.
It probably had radios and radars butchered in also...and acc power for possibly a laptop and a dash cam.
Don't even get me started on the lo-jack type of remote location finder the cop shops use on every vehicle they have.
Side mounted spot lights....yep.
roof mounted light bar.....yep.
PA system and high output horn.....yep
remote open rear doors if it was a K9 unit....yep.
The list goes on and on.
Umm, I very seriously doubt anyone has dropped a penny in the cigarette lighter since cop cars haven't had cigarette lighters since the Nixon era.
But by all means look |
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PhilAIV
join:2002-02-16
Carrollton, GA
clubs:
 ·AT&T Southeast
| StNickless & THUD300 are probably on the right track.
Look at the vin #. If it has P71 in it then it is a police interceptor.
Prior to 2003, police interceptors weren't equipped with a factory harness for a wig wag controller therefore they'd have to cut and splice wires. I've seen plenty of p71's where police departments have ripped out their controllers without fixing the wires back correctly. |
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thedragonmas
join:2007-12-28
Albany, GA
| reply to TheHarvester
said by TheHarvester :All this is assuming the vehicle is the 4.6L SOHC vin 6. What is the 8th digit of your vin number. I don't think it will change things but it may. 8th digit is a W,
said by PhilAIV :StNickless & THUD300 are probably on the right track. Look at the vin #. If it has P71 in it then it is a police interceptor. Prior to 2003, police interceptors weren't equipped with a factory harness for a wig wag controller therefore they'd have to cut and splice wires. I've seen plenty of p71's where police departments have ripped out their controllers without fixing the wires back correctly. yup.
found a few cut wires in the trunk, probably went to their recording setup, or who knows. taped them up and tryd again, still blows. |
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