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EFV-8 Club Forum / 1940 Ford Discussion / Headlight problems

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Posted By Discussion Topic: Headlight problems -- page: 1 2     o2bnkc 10-03-2021 @ 11:58 AM reply profile send p.m. Member Posts: 48 Joined: Mar 2021 I was driving home the other night and my headlights (1940 Deluxe, 6 volt, positive ground) started flickering off and on. I assumed it was a loose or partially broken wire. I've checked all the wiring that is visible and didn't see anything damaged. Under the dash, the headlight wire was hot to the touch. The voltage coming out of the dash switch was 6.37, so I assume the switch is ok. Where do I go from here? Thanks. A Proud Navy Vet ford38v8 10-03-2021 @ 12:38 PM reply profile send p.m. Senior Posts: 2737 Joined: Oct 2009 Your headlights were flickering from the circuit breaker's being activated by a short to ground. I'd start by tracing down the warm wire. Alan This message was edited by ford38v8 on 10-3-21 @ 12:39 PM o2bnkc 10-03-2021 @ 2:24 PM reply profile send p.m. Member Posts: 48 Joined: Mar 2021 Update: The taillight wire is getting hot, also. When I pulled it from the switch, the headlight wire cooled off. I'm really confused now. A Proud Navy Vet ford38v8 10-03-2021 @ 3:31 PM reply profile send p.m. Senior Posts: 2737 Joined: Oct 2009 You’re getting there. Trace it down, there’s your short. Here’s a clue: do you have dual exhaust? Alan o2bnkc 10-03-2021 @ 4:55 PM reply profile send p.m. Member Posts: 48 Joined: Mar 2021 Single exhaust. After further testing, both the taillight and headlight wires are overheating when I pull out the switch. I've traced the headlight wire as good as I can, and see no problems with that. I haven't traced the taillight farther than the firewall yet. I will crawl under the car tomorrow. I assume the taillight wire goes under there. Where is the circuit breaker for this? A Proud Navy Vet This message was edited by o2bnkc on 10-3-21 @ 4:55 PM ford38v8 10-03-2021 @ 6:24 PM reply profile send p.m. Senior Posts: 2737 Joined: Oct 2009 You have one single circuit breaker that serves all lighting on the car. You’ll find it high on the firewall behind the dash, above the steering column. Where exactly are the wires located that get hot? Have you traced these wires to both ends looking for the short? Have you checked your dimmer switch? These dimmer switches are notorious for being unreliable. Alan o2bnkc 10-03-2021 @ 8:38 PM reply profile send p.m. Member Posts: 48 Joined: Mar 2021 Is it by the ignition resistor? The headlight wire gets hot right behind the dash switch. The taillight wire gets hot where there is a connection to the rest of the wire on the engine bay side of the firewall. It connects to a bigger loom as it goes down the firewall to the underside of the car (it looks like) I haven't crawled under there yet. I traced the headlight wire to both headlights and don't see any damage. I haven't even considered the dimmer switch since I never touch it. A Proud Navy Vet This message was edited by o2bnkc on 10-3-21 @ 8:41 PM ford38v8 10-03-2021 @ 9:06 PM reply profile send p.m. Senior Posts: 2737 Joined: Oct 2009 Ok, here’s another possibility. You say they get hot at connections? The wiring was replaced in 2012? If connections are allowed to oxidize, they can overheat, and deliver less power as a result. You don’t have to be anekectician to go through your connections cleaning, applying a spot of grease, and tightening. And if there is a short, a multimeter can show it. Alan o2bnkc 10-05-2021 @ 6:28 PM reply profile send p.m. Member Posts: 48 Joined: Mar 2021 Can the light switch be causing these problems? A Proud Navy Vet TomO 10-06-2021 @ 9:34 AM reply profile send p.m. Senior Posts: 7243 Joined: Oct 2009 If the power wire going to the light switch is warm to the touch, the problem could be the light switch. But you said that some of the wires are hot to the touch. Those wires are carrying more current than they are rated for, so the problem is caused by a poor connection in these wires or a short to ground in these wires. You said that the headlight wire was hot coming from the switch and that the tail light wire was also hot. The tail light wire is a black wire that has a connector at the switch, another connector at the bundle of wires that comes through the firewall and double connector at the rear of the car for the tail lights. Check the wires to each of the tail lights to see if they are hot. If one or both are hot your bulbs are drawing too much current. Did you install halogen bulbs? If so replace them with normal or LED bulbs. If the wires are cool, check the wire to the license light. If it is hot, check it for bare spots. If the wires at the back of the car are not hot, go back to the engine compartment and check the black wire going to the tail lights. If it is hot, disconnect the bullet connector for the black wire and clean the bullets. Reinsert the bullets into the connector and check again. Tom

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