interesting head light fail

[Dave WM]

I took a long road trip, several hours of night driving (i generally avoid night driving). hours into it i notice one head light seems seems very dim, the other still on but def not full bright. 

While stopping for gas I get out to look it over and while inspecting the very dim goes out completely. luck holds out on the other and I make it to daybreak.

1st place I check is the fuse box, good one is very hot other out. I pull them both, each shows signs of distress, partial melted.

Replaced and all good again. Not sure why the partial melt down vs full blown, and all good now after more extended night running.

 

[siteunseen]

Clean/shine up the connections? 

[SteveJ]

What wattage headlights are you running? If the fuse was heating up enough to melt the solder (Yes, I've seen that happen.), a weaken connection would limit the amount of current that could flow. The good one might have partially failed, too, but not enough to take it out. You're also pushing more current through that circuit with the backfeeding of the other headlight.

When you're doing the cleanup that @siteunseensuggested, don't forget to clean the contacts in the fuse box.

And get off your duff and move up here so we can hang out.

[Mike]

I also highly recommend installing the headlight wiring upgrade with the relays.  This will limit the voltage into your cabin at a lower amperage.  It's great for older wiring and this harness uses your existing connectors (without cutting or splicing).   https://www.thezstore.com/page/TZS/PROD/classic10d23/12-4651

[SteveJ]

1 minute ago, Mike said:

I also highly recommend installing the headlight wiring upgrade with the relays.  This will limit the voltage into your cabin at a lower amperage.  It's great for older wiring and this harness uses your existing connectors (without cutting or splicing).   https://www.thezstore.com/page/TZS/PROD/classic10d23/12-4651

The problem is getting the connectors for the 280Z headlights. I could work around that in the 74-76, but even that involves backing pins out of the connectors between the dash harness and engine harness. 

See @Dave WM, even more reason to come up this way. There are even a couple of Publix around here for your wife.  

[Mike]

2 minutes ago, SteveJ said:

The problem is getting the connectors for the 280Z headlights. I could work around that in the 74-76, but even that involves backing pins out of the connectors between the dash harness and engine harness. 

Ah yes, this harness upgrade is only for the 70-73 series.  I wasn't sure because he didn't mention the model in his original post.  So is it possible to adapt the harness?  It doesn't appear that MSA has one for the later model cars.

[Dave WM]

on a prior trip a strange fail, i would show sudden slight discharge for a second then a massive overcharge (like 30amp indicate by the ammeter) for several seconds. it was so bad that i was concerned with frying the ECU, so I would turn on the lights just to try to load down the battery voltage. This happened repeatedly for hours while on the same long trip I finally got to my location and was able to buy a replacement alternator which fixed the issue, I had to turn in the old alternator and was never able to autopsy it to find out what was the base problem. I eventually repaired my orig alt that failed early in my owner ship (shorted diode pack), reinstalled it and have been running every since. 

anyway my theory the fuse issue is perhaps those sustained high voltage/current event may have damaged the fuses (the head lights were MUCH brighter during the event, I am sure the higher voltage was causing a much higher than normal current in the head light circuit. I don't recall replacing the fuses after that trip, and a almost never run my lights as i generally avoid nite driving. 

I have inspected the fuses/fuse holder/combo switch all look very good, no corrosion at all. i have not checked the actual head light connection but will do that as well. I assume the head lights are stock replacements, based on the brightness I dont think they are high wattage.

Edited December 2, 2021 by Dave WM

[Dave WM]

15 minutes ago, SteveJ said:

The problem is getting the connectors for the 280Z headlights. I could work around that in the 74-76, but even that involves backing pins out of the connectors between the dash harness and engine harness. 

See @Dave WM, even more reason to come up this way. There are even a couple of Publix around here for your wife.  

recently retired (sorta anyway) so hope to make a run to the dragon soon, missed it last year, but now work is much less an issue.

[Dave WM]

an jeez my trip home on 75 was a nightmare i start south from tifton, all the way to the fl t pike, min speed in fl is about 80 lest you get run over, truck running 3 wide at times, at one point i looked down and was north of 95mph, and just keeping up... do my best not to get squashed like a june bug. next time i may go the fl/ga parkway a little on the west side of the state but very little traffic, comes up thru monticello then on to albany.

[Dave WM]

for my dragon run i am going to look into us 301, looks promising

[SteveJ]

2 minutes ago, Dave WM said:

an jeez my trip home on 75 was a nightmare i start south from tifton, all the way to the fl t pike, min speed in fl is about 80 lest you get run over, truck running 3 wide at times, at one point i looked down and was north of 95mph, and just keeping up... do my best not to get squashed like a june bug. next time i may go the fl/ga parkway a little on the west side of the state but very little traffic, comes up thru monticello then on to albany.

In Georgia, they think the signs identifying the freeway are the speed limits. If you think I-75 and I-85 are bad, you should try GA-400...

[Dave WM]

i like 280 up (or 82 or what ever it is, gets confusing with so many shared rd numbers) from tifton all the way to phenix city. nice divide hiway, very low traffic (until you get to columbus anyway) interesting sites (like the little grand canyon) along the way. just have to watch out for the dear esp around ft benning.