Short in 46 lighting circuit

[oldford2]

I have a short somewhere in my lighting circuit. Just started intermittently and now always. When I pull the switch on to parking lights the ampmeter pegs left all the way and lights are barely visible. When I pull all the way the headlights come on but the needle stays pegged. I have unplugged all 4 lights (rear left and right and fronts left and right) separately trying to isolate a defective light. Still the short. I have "wiggled" and tried to check the main cables with no luck. Now I suspect the switch may be the culprit and wonder if a bad switch could cause this sympton? Anyone ever had a bad switch?
John

[Vic Piano]

John, just a wild guess but when you had the body work done on the rear door/fender were any of the wires going to the tail lights/brake lights/gas sending unit/license plate light, messed with, cut, painted, etc... Somewhere in there could be the source of the problem.

[oldford2]

Vic,
That was my first thought because I had the rear lamp assembly off to remove the fender and then had to re-install it when the fender was put back on. So I doubled checked that light and as mentioned, I unplugged it in my trouble shooting. Fluid leaks I can always trace down, but hard to see electricity leaking. I need to find this because next week is the first Hemmings cruise-in up in Vermont and we will be coming home in the dark. John

[Henry/Kokomo]

Well, you know the short is downstream from the light switch and it appears to be in the parking light circuit. If you think it's the switch, disconnect all wires from the light switch except the one feeding the switch. If the switch is shorted, you'll still get the heavy discharge when you turn the switch on even with no lights connected. If the switch is OK, replace the lighting wires one by one, testing after each wire, to isolate the short circuit. After you've found which circuit is the culprit, you'll know which wires have to be traced to find the problem. I think Vic has a good idea, given that you've had body work done recently. Also, don't overlook the dash light circuit. Sorry for the long winded post.

[oldford2]

Henry,
Thanks for the switch test idea. I will try it.
John

[ford38v8]

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John, remember that your interior lights are also on the same circuit. Dome lights have been found guilty of shorting out without apparent reason.

[oldford2]

Well, thanks to help on the Fordbarn I have solved my short circuit problem. A few days ago I was busy in my trunk installing a trunk lid lock to prevent it from falling accidently. Up and down many times to install/test and must have disturbed the wire to the trunk light which was bare.

Found this bare wire touching the trunk frame



Thanks again,

John

[Bruce Lancaster]

Next...is system hooked to circuit braker correctly? Seems to me your lights should have been cycling 0n-off with the breaker during the trouble.

[oldford2]

Bruce,
Each time I turned on the lights to see if I had found the bad area, I only left the needle pegged for 3 to 5 seconds and then turned it right off. Maybe not enough time for the breaker to work. But I will check out that connection too. Thanks
John

[Steves46]

John, glad to hear that you resolved the problem. I have found in most cases when a glitch occurs, it's ususally related to the last thing you were messing around with. Now if I can only figure out why my perfectly good clock stopped working! I wasn't starring at it so on to more troubleshooting.

[Vic Piano]

John, where did you get the "trunk lid lock"... and will it work on a convertible

[Henry/Kokomo]

John - Glad you got the problem solved. Steves46 is right on target. . . where were you working last? Been caught that way mself more than once!

[oldford2]

Vic,
I made it myself from a piece of channel. Apparently plans were published in a 1999 issue of Ford times and a fellow barner sent me a scan of the lock. I imagine you have the same lid supports in your convertible. This replaces the broomstick handle many folks use. I will make you one and install it in November. Requires drilling and tapping a 1/4-20 hole in the brace.

I had a piece of 1" channel with slots in it, Cut a piece off to length. Then made a bushing to slide on the 1/4-20 bolt to make a shoulder bolt. The lock slides freely in the slot. When the lid is lifted, the lock slides down the brace automatically and locks the 2 arms from folding. To close the lid, lift the lid slightly with your right hand and slide the lock up and let the lid down.
John

[Graeme / New Zealand]

Nifty idea John and simple too. I've "sconed" my head on more than one occasion.

GB

[peteyshoes]

john, judging by your pics, it appears the wiring in your car is old/original? might be a good idea to chase thru the whole system before your trip. could save a headache on the road. just a thought.

[42guy]

John.
I just received the head light harness from dimmer switch forward. I got it from C&G in CA. and looks like quality material. Suppose to be American made.

[oldford2]

42 guy
Richard, Keep me posted how your harness installation goes. I need to think about wire harness replacement. Your headlight harness must include the parking lights too? Can you make it to Hemmings next Thursday. If not, maybe I will stop over some day.
John
[email protected]

[Vic Piano]

Originally Posted by oldford2

Vic,
I made it myself from a piece of channel. Apparently plans were published in a 1999 issue of Ford times and a fellow barner sent me a scan of the lock. I imagine you have the same lid supports in your convertible. This replaces the broomstick handle many folks use. I will make you one and install it in November. Requires drilling and tapping a 1/4-20 hole in the brace.

I had a piece of 1" channel with slots in it, Cut a piece off to length. Then made a bushing to slide on the 1/4-20 bolt to make a shoulder bolt. The lock slides freely in the slot. When the lid is lifted, the lock slides down the brace automatically and locks the 2 arms from folding. To close the lid, lift the lid slightly with your right hand and slide the lock up and let the lid down.
John

Thanks John, I'm getting tird of getting hit in the head by the '47 rag tops trunk lid just about every time I open it. Vic