Why did my headlights kill my car?

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cruiser

cruiser

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Hi Guys/Gals: Here's a strange electrical failure that I've never seen before. About a year ago, I began having some issues with the hi beam/low beam selection on the headlights on my very stock 1974 Duster. All wiring is factory original, but the foot operated dimmer switch was replaced two years ago with a new Echlin part (DS-112 from NAPA). I began to notice a fault that would come and go. When driving at night in high beam, the headlights would go out. When I shifted to low beam, the headlights came back on in low beam. A week ago, the high beam lights went out again while driving at night. Shifting to low beam didn't help - the lights were still out. Then they began to flicker, so I pulled over. As I pulled over, the entire car went dead. Absolutely nothing. I changed out the ballast resistor, but that didn't help. About two minutes later, I noticed that the interior lights had come back on. So I tried starting the car and it worked. As long as I drove in parking lamp only (no headlights), everything was fine. So what's going on? I learned that the headlights are not protected by a fuse, but by a circuit breaker. Is it possible that something shorted internally in the dimmer switch and opened up this circuit breaker? I suspect that once the breaker cooled down, that it closed by itself regaining electrical control of the car. If so, why would an open headlight CB kill an entire car? I replaced the dimmer switch with a new Echlin one and everything works perfectly now. Any ideas? Where is this circuit breaker located? Have I damaged anything in my electrical system? Ideas?
 
Get out your wiring diagram and start at the headlight connector and trace back to the battery.

Along the way see where the power to the ignition taps into the the system bact to the battery.


Just a while *** guess. The main splices, ammeter, or bulkhead connectors would be my bet for an intermitant complete electrical loss.


As to why..

Lets say you have a bad connection in the bulkhead connector on the main battery / alternator connectors. To just run the car the resistance is not too much and it runs ok. Now add the additional current of the headlights, the bad connection starts to heat up creating additional resistance to the bad connection. You hit the high beams, additional current now the connector heats up enough to brake the connection, (metal in the connector expands) now it sits for a few minutes and things cool off and the metal retracts and makes a connection enough to run the car.

Could the high beam switch caused the problem? I doubt it

Could the headlight switch caused it? Maybe for the lights, but why would it kill the engine????

Now maybe, just maybe, your battery is very low and your alternator is not charging enough and when the lights are on it can't keep up to the load and after a while the voltage is so low that the engine dies.

Does not fit your description of the failure but easy to check.
 
cruiser said:
Hi Guys/Gals: Here's a strange electrical failure that I've never seen before. About a year ago, I began having some issues with the hi beam/low beam selection on the headlights on my very stock 1974 Duster. All wiring is factory original, but the foot operated dimmer switch was replaced two years ago with a new Echlin part (DS-112 from NAPA). I began to notice a fault that would come and go. When driving at night in high beam, the headlights would go out. When I shifted to low beam, the headlights came back on in low beam. A week ago, the high beam lights went out again while driving at night. Shifting to low beam didn't help - the lights were still out. Then they began to flicker, so I pulled over. As I pulled over, the entire car went dead. Absolutely nothing. I changed out the ballast resistor, but that didn't help. About two minutes later, I noticed that the interior lights had come back on. So I tried starting the car and it worked. As long as I drove in parking lamp only (no headlights), everything was fine. So what's going on? I learned that the headlights are not protected by a fuse, but by a circuit breaker. Is it possible that something shorted internally in the dimmer switch and opened up this circuit breaker? I suspect that once the breaker cooled down, that it closed by itself regaining electrical control of the car. If so, why would an open headlight CB kill an entire car? I replaced the dimmer switch with a new Echlin one and everything works perfectly now. Any ideas? Where is this circuit breaker located? Have I damaged anything in my electrical system? Ideas?
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Check your bulkhead connector under the hood on the firewall... It sounds like your front end wiring harness is loosing it's connection with the bulkhead connector...

Also pull the headlight switch out of the dash and check to make sure the connection is tight and none of the wiring has melted part of the connector that goes on the switch... If the headlight circuit gets overloaded or bad connection, the main power wire will get hot and melt the hole in the connector that it goes into...

Next, make sure that the connector to the foot dimmer switch has good connections...


And as stated above, check your grounds to make sure they are good.. Take them apart, wire brush or scrape them with a screwdriver to remove any crud and get exposed metal, then put some dielectric grease on them and connect them...
 
krazykuda said:
Take them apart, wire brush or scrape them with a screwdriver to remove any crud and get exposed metal, then put some dielectric grease on them and connect them
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If you do as said you will expose the base metal of the connector and cause additional accelerated corosion.

Also dielectric grease is an insulater and has no place on the contact points of a connector. Maybe the connector will displace the greese, but you can float a battle ship in a 1 molecule thick sheet of water. To think that the grease will be fully displaced probably will not happen

 
Dielectric grease does not affect well made connections. It is used commonly and will improve conduction over time as it prevents corrosion. It cannot prevent corrosion unless it intimately coats the mating surfaces you are trying to prevent from corroding. There are a lot of myths about this.
 
Dana67Dart said:
If you do as said you will expose the base metal of the connector and cause additional accelerated corosion.

Also dielectric grease is an insulater and has no place on the contact points of a connector. Maybe the connector will displace the greese, but you can float a battle ship in a 1 molecule thick sheet of water. To think that the grease will be fully displaced probably will not happen

Click to expand...

Dammit! I just got done doing this with my American Automotive bulkhead. I swear it was in the instructions. GAH!!! Ill have to check. I could swear they also said to seal the outside with something....Now I am questioning my existence altogether!
 
What is your voltage at the battery with the engine idling ? I suspect this may be a charging issue is why I am asking.
 
Dana67Dart said:
If you do as said you will expose the base metal of the connector and cause additional accelerated corosion.

Also dielectric grease is an insulater and has no place on the contact points of a connector. Maybe the connector will displace the greese, but you can float a battle ship in a 1 molecule thick sheet of water. To think that the grease will be fully displaced probably will not happen

Click to expand...


Worst advice ever. Grease the piss out of those connectors. Literally if required.

bcschief said:
Inside the headlight switch.
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Beat by 4 minutes. This> Replace the headlight switch.
 
Dana67Dart said:
If you do as said you will expose the base metal of the connector and cause additional accelerated corosion.

Also dielectric grease is an insulater and has no place on the contact points of a connector. Maybe the connector will displace the greese, but you can float a battle ship in a 1 molecule thick sheet of water. To think that the grease will be fully displaced probably will not happen

Click to expand...



I said that about the grounds, not the connectors...

Read my post, that's why I split up the sentences to make the different points separately..
 
bcschief said:
I believe most auto manufactures used what they called brown cup grease. A light grease similar to lubriplate.
Click to expand...

The grease off my teenage forehead is better than no grease at all, in electrical connectors.
 
I would start at the battery connection. A poor one will overheat and fail, but a change in load can sometimes cause an arc that cleans a spot and continues to carry current.

The battery connections might be fine, but I've seen so many poorly connected ones cause trouble that it's the very first thing I do on any car these days..
 
So, I had a really wierd situation as I was putting my Duster back together. It wouldn't start unless the headlights were on. I could shut them off after it was started and it would stay running but, wouldn't shut off unless I turned the headlights off. It wound up being the ground for the headlight curciut. Its in the harness under the battery tray there are 4 or 5 ground wires that clamp together into one main ground that i believe goes to the headlight switch if I remember correctly. Either way it was all corroded where the wires came together under the battery. When chasing this stuff start simple. Start by turning on the headlights, unplug the plug at the headlight and check for voltage with a test light, only one side should have power with the lo beams on then, 2 should have power with the hi beams on. If you have power at all 3 wires then you have a bad ground in the circuit. From there just open the harness and follow it back to find where the problem is coming from. Good luck!! Electrical things can drive ya crazy but, keep it simple..power and grounds is all it needs...don't over complicate it.
 
Years ago, I had to drive my 64 340 Dart from Woodburn(OR) All Mopar drags to tri cities Washington for the hydroplane races, and my H4 headlights started to overheat my headlight switch and my headlights would turn off while doing 70mph. Not fun. So I pulled the switch from my dash and let it hang down in the vent air coming from the vent box on the driver side foot well. It worked to keep my headlights on and me driving the rest of the way without playing peek-a-boo with dark roads at freeway speeds. Not a permanent fix, but it worked for me.
 
I'm not smart enough to advise you as to why the headlights killed the car. My guess is a bad connection at the firewall connector or bad ground(s). That said, read on.

Post #17 eludes to what I'm fixin to say.


The stock headlight switch on older cars was never designed to properly carry the loads. They were designed as a cheap and quick to manufacture mass production switch. The factories should have been using relays in headlight circuits way back as early as the 40s.

That said, even when everything is in good condition, the wiring on these older Chrysler products needs some help. @crackedback's headlight harness kit adds substantial wiring and relays to take the load off the headlight switch and allows the relays to carry the load like they are designed to do. The mod also allows 100% alternator voltage at the headlights for brighter operation. No, the headlight system won't be stock anymore, but it will be much better for carrying the load and your headlights will be much brighter. I also strongly recommend upgrading to H4 halogen headlamp conversions at the same. You'll see a night and day difference. I cannot brag on Rob's kit enough. It has been the single most best bang for the buck I've done to my car. I also upgraded to Cibie H4 halogen headlamps at the same time.
 
RustyRatRod said:
It's entirely possible.
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I also had a starter relay failure at about the same time as the total electrical failure. I replaced the starter relay yesterday. Both the battery positive cable and the main electrical feed from the battery go through the starter relay. I wonder if somehow the failure of the starter relay had something to do with this.
 
cruiser said:
14 volts
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Ok then I would say no issues with the charging system. You see an alternator with 1 of 3 phases burned up will charge 11.5- 12.0 volts which will charge the battery enough to not appear to be a problem until you put a load such as the headlights on it. But also check the voltage with it running about 1000 rpm if you see more than 14.2- 14.5 volts the regulator is not controlling the alternator properly.
 
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