Headlights burning out

[Troy]

This is on my 70 Challenger but set up identically to my 68 Charger (that isn't finished). The previous owner put relays in for the low and high beams. I've had the car for 7 years with no issues. During that last round of fixes/upgrades I replaced the dash harness (and engine harness if it matters). During the first night drive, a few minutes in, the headlights flickered fairly dramatically and then went out. I was able to get home on the high beams. After replacing the low beams, the next time out in the car the same thing happened. I put on the high beams and made it about a block before they also flickered and burned out. These lamps are hard to come across locally but I managed to round up 2 high beams and 1 low beam. I had suspected that perhaps the lamps were getting too much voltage so, when I got to the car, I pulled the wiring from the relays and connected everything in the stock configuration. I made it home and on a few trial runs since without issue. I've also picked up another low beam to complete the set.

I'd like to reinstall the relays but I'm concerned that I haven't found the actual problem. I don't see any obvious spikes in the gauge. I put a multi-meter on it but only while in the garage. I suspect the load is greater on the road. I do have a small LED gauge that I could install temporarily. I purchased a new voltage regulator just in case.

What could cause this problem? How do I test it? Why does it work fine without the relays (and why did it work fine for many years before the new harness)?

Thanks,
Troy

[Nacho-RT74]

it is way noticeable if they burn for voltage because will get WAY HIGHER intensity before burns out.

Load is requested by the light, not sent by the amm or the batt, no matter if with or without relays

the only I can think off is they get lot of grease during installation making hot the glass and overheating all around.

I guess they are sealed beams. Is hard that happens on sealed beams ( is more common on repleaceable bulbs ) but still

[Troy]

Yes, they did get really bright before burning out. And, in each instance, I was at a stop light - not driving/cruising. Car was warm.

Yes, they are sealed beams. The lamps had been in the car at least 18 years and I hadn't touched them as far as removal/replacement. The relays have been there for 7 or 8 years and I haven't touched that wiring either. The only thing I touched recently was the connector to the new dash harness - but, with the relays, that is only supplying enough power to switch the relay.

The current voltage regulator is an electronic version I believe. Supposedly more reliable.

Troy

[Nacho-RT74]

Halogens? or standards ?

would check for voltage. Being at a stop light I guess car in N and warm, iddle raises up... it can be very well a voltage failure.

Electronic voltage regulator is more reliable but not saved from fail

[Troy]

Halogen. Car is a stick shift. I have a new regulator sitting here but I hate to just swap parts while not having any idea what the problem actually is.

Troy

[Nacho-RT74]

check for voltage with car warm with a reliable multitester

[Nacho-RT74]

weird is the sealed beams got burnt before any other bulb!

[Troy]

That's why I was wondering if it was due to the relays giving them direct current. They work fine with the "as stock" wiring it seems. Another thing I had read was that maybe there could be a slightly loose connection in there which could cause the regulator to spike(? just going from memory). It's possible since some of the wires pulled out of the relays rather easily. But then it would have to be the same situation on both relays as the low and high beams went out separately (but both lights on each circuit at the same time).

And again, it's been this way for years.

Troy

[Pete in NH]

Hi Troy,

Like yourself, I suspect an intermittent connection  or poor ground at the voltage regulator that is allowing the system voltage to spike up. A bad ground at the voltage regulator or intermittent connection like at a bulk head connector pin can cause the voltage regulator to think the system voltage is lower than it is and try to raise the system voltage. The halogen bulbs are more sensitive to this because they operate a much higher temperatures than conventional bulbs so it takes less to push them over the edge to failure.

The relay system removes much of the voltage loss in the original wiring system. But, it is that voltage loss in this case that is protecting the halogen bulbs from the excess system voltage caused by the voltage regulator not working properly. It gives you a good idea of how poor the original headlight wiring is in terms of voltage loss.

I would rig up a voltmeter to monitor the system voltage while you drive. An analog meter ( with a needle pointer) would be best as they react faster than the newer digital meters. Take a passenger along for a ride to watch the meter That way they can constantly watch the meter and you can keep you eyes on the road. I would not be surprised if the voltage is going up beyond 16 to 18 volts on occasion as the alternator goes wide open when the regulator looses control. As I mentioned it could be a poor ground, bad connection or a failing voltage regulator. once you find the problem you should be able to run the relay upgrade without issue.

[68 RT]

Did your dash lights get brighter too? If not I would buy some new relays and try them. Also did you look at the amp/volt gage? Did it go up or down a lot? I've had bright light problems 2 times in about 20 years in my Charger and it was voltage regulator both times. But the bulbs never burnt out. If dash lights did not brighten I would say bad relays. The way I see it if you took the relays out of the picture and it stopped doing it they were the problem? Electrical problems can suck!

[Troy]

Thanks guys. The plugs were very stiff to fit into the bulkhead connector on the new harness. I tested it all afterwards and it seemed the connections were good.

I haven't noticed the amp gauge swinging. It feels as if it's typically high (consistently) but I have nothing to compare it to. I think I actually have a contraption (it's like the size of my grade school lunch box!) with a needle scale. I bought it specifically for times like these (now that I think of it) when digital doesn't catch the fast fluctuations. And it was a closeout so I don't have much in it.

I haven't noticed the dash lights going brighter or fluctuating. It's possible that the flickering headlights distracted my attention though.

The relays are Hella and tested good. I have a pile of spares (bulk buy when I upgraded 3 cars at once). They all test the same - but sitting on a bench isn't the same as real world performance. I thought all this stuff was solid state? The only concern was the wires that didn't feel terribly tight. I have a box of the "correct" Hella terminals that I use when installing new ones so I'll make sure to install those when I put it back together.

68 RT: I'd agree that the relays were the obvious problem *IF* the factory wiring wasn't such a drain. It's amazing how much brighter lights are when they're getting power directly from the battery/charging system through a good quality wire.

I could just put on the new regulator and rewire the relays. If it's fine I still won't know what the actual problem was. I do know the relays are probably 20 years newer than the regulator...

If I leave the relays off then it will look like I have a hacked up headlight harness. Ick!

Troy

[Nacho-RT74]

Feed relays from alt stud

[daveco]

It would make sense that the headlights would be the first to suffer from a voltage spike. The relay setup allows full system voltage, the rest of the lights are still being "choked" by the stock wiring.

[Nacho-RT74]

thinking on that, yes is posible.

My headlights setup are running through the stock wiring thougth so I'm saved from that LOL. I have the relays on kick panel. Just saving the headlight switch and floor dimmer switch points, but I took the trigger just right out from the floor dimmer switch, so still running half of the system imcluding bulkhead conector.

and positive source is taken from the ammeter stud, everything inside the cab

[flyinlow]

You might try some troubleshooting by elimination.

Assuming you have a healthy fully charged battery , unplug the regulator and drive the car ( or let it sit in the driveway) with the lights on running with relays. You should be able to go 30 minutes on the battery.

The difference I noticed with relays was about 1-1.5 higher volts at the headlight compared to stock 40 year old wiring. I don't think Chrysler designed the resistance in their system to extend bulb life.

I use Hella housing with halogen bulbs. They receive around 14.5 volts without problem. Just like a real car does.

I have seen systems run at 16 volts without burning out the bulbs quickly. Above that    What alternator do you have that can produce high voltages at idle under headlight /brake light load?

Sounds like a regulator/ground issue. 

[Troy]

Ok, thanks. It's finally not raining so I'll try to test it after work. I found some detailed testing procedures on the internet but they can get fairly involved (and involve jumper wires which are at my garage). I do have a digital multimeter at home with the car.

If it's a ground it's entirely possible that it would be "fixed" by just replacing the regulator - which is why I want to verify that it is actually broken. As mentioned, the harnesses are new so I suppose something could have shifted or loosened when installing them.

Troy