73 Headlights cutting out while driving?

[Jimmy P.]

I just had a scary ride home from a local vette together this evening. About a mile into my trip home my headlights started cutting completely out.😱 The first time they came right back on, then each time after they stayed off a little longer. Then they stayed on the rest of my trip home,thankfully. It happened with just the low beams on, and I put on the high beams and they all went out.
Could changing the lamps have anything to do with this? When I bought the car it had halogen lamps in it and I drove it home At night from West Chester Pa. to my home over 200 miles on the Pa. Turnpike with no headlight problems at all. Recently I just purchased two brand new OEM Guide High Beams and two used OEM Guide Low beams and installed them in the car. A couple of weeks ago they went out once and came back on and stayed on, unlike what I experienced tonight. I also installed a new headlight switch this spring because my headlights weren't coming up and I had to use the bypass.
Any help with what I should check to see what is causing this would be greatly appreciated.
Thank you

[Mark E.]

Re: 73 Headlights cutting out while driving?

Check for a poor connection somewhere between the battery and the lights. That path includes the ground wire from the battery to the frame and body of the car, to the dashboard and the positive wires from the battery to the fuses, switch etc. all the way to the lamps.

If this problem didn't happen before the headlights were replaced, then begin by checking the connections and wiring you messed with. Don't underestimate the effect of a poor ground connection somewhere. Check and clean grounds even if the look ok, especially the ground wire on the left front of the core support.

Are the lights also flickering or just cutting out for a period? If flickering, it could be from a failing rectifier in the alternator. Rectifiers convert AC voltage to DC voltage. When one fails, it allows an AC ripple voltage into the vehicle's electrical system causing the lights to flicker.

[Jimmy P.]

Re: 73 Headlights cutting out while driving?

Thanks Mark,
I will check all the wires that I messed with while changing the lights. I did notice that one of the headlight wire connectors (plug in) was replaced. I will also check the grounds to make sure they are clean.
the lights do not flicker at all, they just go completely out.
Job will have to wait. Leaving for vacation in the morning. I just hope I'm able to get them to go out while I'm checking the wires, or grounds, so I know exactly what caused it. If not, I'll be worried every time I drive at night (which is never too often) that they are going to go out. Pretty scary and dangerous
Thanks again,

[Jim T.]

Re: 73 Headlights cutting out while driving?

Jimmy since you have changed the light switch I would also consider the new light switch as being the problem. If you still have the old switch and know how to change the switch, it will be not to difficult to check out the new switch as the problem. The light switch if I remember correctly operates through a circuit breaker to protect wiring.

[Jimmy P.]

Re: 73 Headlights cutting out while driving?

Thanks Jim,
i do still have the old switch, even though the vacuum part of it does not work. After checking the wiring around the headlights, I will try your suggestion. I hate the thought of removing the switch again. I noticed the used lamps were a little smokey/foggy, slight Edison Effect, this wouldn't cause them to go out would it?

[Dan K.]

Re: 73 Headlights cutting out while driving?

Hi Jimmy.

I've seen other posts about this topic and more than one person pointed out the dimmer switch on the floor. My 65 did that to me once, not fun!!! Pumped the dimmer switch like a mad man twenty or thirty times and it hasn't done it since. Coincidence? Give it a shot.

Dan

[Jimmy P.]

Re: 73 Headlights cutting out while driving?

Hey Dan, I never thought of that one. Will add it to the checklist. thanks. Now that this happened, I won't be comfortable at all driving it at night, even to see if the problem has been corrected. It just never ends with these old classics, you get one thing fixed and something else pops up I appreciate all the suggestions.

[Gary S.]

Re: 73 Headlights cutting out while driving?

"Pumping the dimmer switch"reminded me of a beater Chevy pickup I bought that had the floor mounted dimmer. I was driving it and, like you said, the low beams went out - no blinking, just out. I hit the highs and the lights came back on. It was an easy fix to replace that witch.

[Jimmy P.]

Re: 73 Headlights cutting out while driving?

Had the high beams on too when and everything went dark. So, it is just not the low beams. I am away on vacation now, so I haven't been able to work on the car to try any of the suggestions from you guys. It doesn't seem like this is going to be an easy fix. Just trial and error and nerves of steel to test each attempt at a fix by driving at night! I hate to buy new switches if I'm not sure that one or the other would be the problem. Most of the vendors will not take electronics or switches back as a return. Just from the responses I've received I guess I can rule out the used lamps as the culprit? And I should assume it is either the headlight switch or the dimmer switch
thanks guys,

[David H.]

Re: 73 Headlights cutting out while driving?

... And I should assume it is either the headlight switch or the dimmer switch
thanks guys,

Don't assume anything. The first response in this thread was to check grounds - excellent advice. Start with simple and cheap.

[Joe R.]

Re: 73 Headlights cutting out while driving?

Just trial and error and nerves of steel to test each attempt at a fix by driving at night! I hate to buy new switches if I'm not sure that one or the other would be the problem. Most of the vendors will not take electronics or switches back as a return. Just from the responses I've received I guess I can rule out the used lamps as the culprit?

Jimmy, I had a similar experience with my car on it's first long drive (2 hours from home). Fortunately I happened to be following a friend who had headlights. I would recommend doing that until you're sure you have the problem licked. I would troubleshoot the car as it stands, don't replace parts unless you're sure they are bad.
Joe

[Michael W.]

Re: 73 Headlights cutting out while driving?

There's a self-resetting circuit breaker inside the light switch. Sounds like that's being tripped.

[Jimmy P.]

Re: 73 Headlights cutting out while driving?

Just got home from vacation late this afternoon and couldn't wait to start trying to figure out my headlight issue. So I went in the garage and started the car and backed it out of the garage. While it was running I turned on the lights to see if I could get them to go out like they did while driving. What I found though, was that only the right side low beam came on. But when I hit the dimmer switch to turn on the high beams all the lights came on and stayed on for about 5 mins. I hit the dimmer switch and the same three lights went out. Would this mean that my dimmer switch is bad, or should I start checking the wiring and grounds. Didn't try anything else wanted to see what you guys thought.
Thanks again for any help.

[Joe R.]

Re: 73 Headlights cutting out while driving?

Just got home from vacation late this afternoon and couldn't wait to start trying to figure out my headlight issue. So I went in the garage and started the car and backed it out of the garage. While it was running I turned on the lights to see if I could get them to go out like they did while driving. What I found though, was that only the right side low beam came on. But when I hit the dimmer switch to turn on the high beams all the lights came on and stayed on for about 5 mins. I hit the dimmer switch and the same three lights went out. Would this mean that my dimmer switch is bad, or should I start checking the wiring and grounds. Didn't try anything else wanted to see what you guys thought.
Thanks again for any help.

Hi Jimmy,

It sounds to me like you have two problems:

1. Left low beam does not work - I would disconnect the bulb and see if you have 12 V at the connector when the right side low beam is working. Or apply 12 V to the bulb on the bench - does it come on?

2. The breaker in the switch Mike Ward mentioned is resetting after a while when a heavy current draw is present. My questions would be how many amps are you actually drawing before it cuts out? And how many amps is the circuit breaker rated for? If it turns out that the circuit breaker is cutting out when it shouldn't, Rich Mozetta may be able to help you repair your switch.

Joe

[Jimmy P.]

Re: 73 Headlights cutting out while driving?

Thanks Joe,
Im not really an electronics guy, but I should be able to perform these checks you've suggested. I'm thinking that I may have a faulty low beam, and I blame myself for purchasing used lamps to cut costs. The low beams had some fogginging when purchased and one of them looked like one of the plug prongs had been re- soldered. Now, i noticed that the fogging in the low beam that is not coming on has gotten worse and there is even a blackish/smokey color in the bulb Maybe this bulb could be causing the wires to heat up going to the switch thus throwing the breaker I still have the replacement halogen bulbs I took out, so I'll plug it back in to see if things work as they should. I did purchase two brand new OEM (old stock)high beams. I have also just purchased two new OEM( old stock ) low beams. Waiting for them to ship out.

Question : when I bench test the bulb do I clip the ground wire in the center prong of the bulb and touch the positive wire to one or both of the other prongs to check if it works?
- As for the amps on my light switch not sure? Just purchased from one the of popular vette vendors.
thanks so much for your help!