Hi guys,

Been having an issue where my drivers side headlight will blow if I use the brights at all. If I don't use the brights, it's fine.
Any tips on where it might be shorting or if this a common issue would be helpful.
1995 Mazda B2300 with 233k miles, original headlights and wiring. Even LED bulbs blow.

Thank you!

 

High beams have a fuse so bulbs shouldn't never "blow"

And LEDs can't "blow", they will dim as they get older, but never just "blow out"

What happens when the drivers side high beam stops working
Passenger side stays on?
What about High Beam indicator on the dash?

If just the high beam on driver side stops working and putting in a new bulb gets it back working then I would guess the bulbs socket is the issue, its heating up and disconnecting the 12volts to that filament/bulb, if it effect both high and low then the ground on that socket would be suspect

 

The bulbs are literally exploding in the assembly. And LEDs obviously don’t blow but I’m assuming a spike in voltage killed whatever LED controller it has.

Passenger side works fine and doesn’t blow so I’m assuming some sort of short on the drivers side. It’s not the socket itself in my opinion because of how the bulbs explode. I’ve literally gone through three packs of bulbs in the last 4 months lol.

 

Maximum volts in a 12volt system is 14.5volts from the alternator which won't hurt anything

A short means + and - are connected together with no resistance/no device in between, this doesn't effect voltage but does effect AMPs flowing thru the wires, fuses are soft wires that melt easily and separate, preventing an AMP surge

Both high beams share one wire and one fuse

I would still look at the bulbs socket for the problem, If it is "shorting" from high beam wire to ground in the socket that should blow the fuse, but if it happened fast enough it may not

I assume low beams work all the time until high beam is activated

 

yeah, you’d be correct with your assumption. As far as I can tell they’ll be fine if they’re just on, it’s been after I activate my brights even for a moment I’ll find the the bulb completely out and exploded in the assembly lol.

I will try to find a socket and order it. Just cut the old one off, wire in the new one, and heat shrink them, you think?

 

Here's another thing I noticed, my alternator will constantly provide 14.6v to the cigarette lighter meter I have.

I have another issue going on where in cold weather my alternator will suddenly stop providing 14.6 and drops down to battery voltage (13-12.6v-ish), a belt squeal will occur and then stop and voltage will rise back to 14.6. I had the alternator replaced and it still happens, so I was thinking it was my AC compressor of unknown condition clutch causing drag on the belt. But I also have a coolant leak, and yesterday I noticed some coolant may have been splashed on it so it could maybe be related or two unrelated problems. Either way, at least for the headlight I will try the socket.

 

in pre-2001 or so Rangers, Alternator voltage should drop down to just under 14volts(13.6-13.8v) after battery has been recharged
Staying high can means battery is failing, no "pushback" when fully charged

Can be wiring or voltage regulator as well, but easy to test with volt meter

Key off
Use alternators metal case as the ground for all tests
Test battery voltage first, that will be your Reference voltage, a good battery will be 12.3v to 12.8v at rest, after sitting over 4 hours

test voltage on B+, the stud/nut terminal on back of alternator, should be Battery voltage exactly

Unplug 3 wire connector on alternator
Test Yellow/white wire, should be battery voltage exactly

Test Greed/red wire, should be 0volts
Turn on key
Re-test green/red wire, should be battery volts, can be slightly less since key is now on

If all 3 wires test OK then wiring in vehicle's charging system is OK

Fan belt slipping/squealing can be a bad bearing in the alternator if voltage drops, slipping on AC compressor or power steering wouldn't effect alternators voltage, because the slipping pulley causes the squealing noise but the fan belt keeps spinning at the same speed, it squeals because the one pulley looses its grip on the belt
Slipping on crank shaft pulley would effect voltage, as that would slow the belt speed down

 

Hi, sorry it took me a bit as it's very cold and windy, and I broke my positive probe trying to get the connector off the alternator. Lesson learned.

Battery tested good at 12.3v an hour after a 5 minute drive back from work.The connector had battery voltage at the yellow and green wires but as far as I could tell with my broken probes, the middle wire was 0v. That may be the ground to the back of the alternator, hopefully? Either way, I believe the charging system is working. I don't have any issues with a dead battery, even though it's the absolute cheapest battery they sold. Could it still be battery?

When this voltage/slipping sound happen, it can be independent of the other issue. Would it slipping on the crank shaft result in the whole system being slowed, power steering included? How would I diagnose that?