here goes. have a 67 convertable. 289v8. no p.s. no tilt, no a.c. manual brakes, just a plain ordinary restored 67. my 7.5A fuse blows instantly for the courtesy lights. my headlights will flicker on and off while driving but stop when i turn on brights. replaced the headlight switch and still had the problem, blew out both headlight bulbs this time! Any help? ive traced as much as i can but am at a loss. the courtesy lights would always stay on replaced the switches still had a problem. Im about lost.
1967 Mustang Convertible Wiring Help!
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Hello. 
:welcome
Normally, when a door jamb switch is bad, the lights won't come on when you open the door. I don't recall ever having seen a bad door jamb switch cause the lights to stay on all the time. For your fuse to keep blowing, you have a short somewhere along the courtesy light circuit. And, if the courtesy lights stay on, it has be shorting out on a wire that has power. Are you saying that the courtesy lights are on even with the key in the off position and with the fuse blown? When the low beams on the headlights flicker, do they do that at an even tempo, or, is it a erratic?
:welcome Normally, when a door jamb switch is bad, the lights won't come on when you open the door. I don't recall ever having seen a bad door jamb switch cause the lights to stay on all the time. For your fuse to keep blowing, you have a short somewhere along the courtesy light circuit. And, if the courtesy lights stay on, it has be shorting out on a wire that has power. Are you saying that the courtesy lights are on even with the key in the off position and with the fuse blown? When the low beams on the headlights flicker, do they do that at an even tempo, or, is it a erratic?
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50 Posts
listen to what veronica says and follow her lead, she's good at this stuff!!
heres a diagram link....
http://midlife66.com/wiring/1967-68_console_wiring_diagram.jpg
heres a diagram link....
http://midlife66.com/wiring/1967-68_console_wiring_diagram.jpg
no, with the fuse blown the courtesy lights are inoperative. they would stay on so i took the bulbs out. the fuse never used to blow but now it blows instantly when replaced. the headlights would flicker erratically but stop when i turned the brights on.Hello.
Normally, when a door jamb switch is bad, the lights won't come on when you open the door. I don't recall ever having seen a bad door jamb switch cause the lights to stay on all the time. For your fuse to keep blowing, you have a short somewhere along the courtesy light circuit. And, if the courtesy lights stay on, it has be shorting out on a wire that has power. Are you saying that the courtesy lights are on even with the key in the off position and with the fuse blown? When the low beams on the headlights flicker, do they do that at an even tempo, or, is it a erratic?
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1,283 Posts
Hey Veronica :yelpleased: I certainly think you're on to something with the courtesy light circuit. I had a bad door jamb switch on my 65. Never saw this before either but my lights would stay on when the switch was completely depressed. I know it doesn't make sense. I tried everything with the wiring circuit and couldn't figure it out. I replaced the switch and it solved the problem. I know the switch grounds to the body of the car. Never had a fuse blow. Could that be part of the problem with deter's car? :shrug
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831 Posts
The instant fuse blow is likely from the power lead in the bulb cup touching the cup. If you look up into the cup under the dash, you will see a spring and a wire at the top. That wire must be right in the middle. Sometimes it will get caught up in the spring and come into contact with the cup, causing a short. Pull out your bulbs and check each one carefully.
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7,185 Posts
Hi again. I thnk that the first thing that I would do is figure out how many problems I had. It is entirely possible that the flickering headlights are unrelated to the courtesy light fuse issue. Try unplugging the dimmer switch and then replace the fuse on the courtesy lights. Your headlight problem, since it is only on the low beams, would have to be between the dimmer switch and the passenger side headlight.. The switch only has one wire coming in and two going out, one for high beams and the other for low beams. If the problem was upstream from the dimmer switch, it would be evident on both high and low beams. By unplugging the dimmer switch, you eliminate that problem from the equation. If the fuse blows instantly with the dimmer switch unplugged, you have at least two different problems. A fuse blowing instantly is frequently a dead short somewhere, and, if the lights were staying on, it's shorting on something that is hot all the time, and that's a pretty short list. Horns, lights, emergency flashers, and ignition switch power feed. If it is shorting on something that's hot all the time, you would be able to detect a draw on the electrical system. Locate the draw, and you have found the problem. This might help.
The Care and Feeding of Ponies: Finding an electrical draw
I thnk that the first thing that I would do is figure out how many problems I had. It is entirely possible that the flickering headlights are unrelated to the courtesy light fuse issue. Try unplugging the dimmer switch and then replace the fuse on the courtesy lights. Your headlight problem, since it is only on the low beams, would have to be between the dimmer switch and the passenger side headlight.. The switch only has one wire coming in and two going out, one for high beams and the other for low beams. If the problem was upstream from the dimmer switch, it would be evident on both high and low beams. By unplugging the dimmer switch, you eliminate that problem from the equation. If the fuse blows instantly with the dimmer switch unplugged, you have at least two different problems. A fuse blowing instantly is frequently a dead short somewhere, and, if the lights were staying on, it's shorting on something that is hot all the time, and that's a pretty short list. Horns, lights, emergency flashers, and ignition switch power feed. If it is shorting on something that's hot all the time, you would be able to detect a draw on the electrical system. Locate the draw, and you have found the problem. This might help. The Care and Feeding of Ponies: Finding an electrical draw
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