Headlights turn on then ahut off real fast

[Tatsbygreg]

On this humvee replaced the headlights because they both went out. Replaces floor dimmer switch. Replaced 3 prong switch. Replaces ground harness. Dont know what's wrong. It's like they draw too much power and turn right backnl off.. is there a relay or something I dont know about

 

[Coug]

On this humvee replaced the headlights because they both went out. Replaces floor dimmer switch. Replaced 3 prong switch. Replaces ground harness. Dont know what's wrong. It's like they draw too much power and turn right backnl off.. is there a relay or something I dont know about

There is an auto resetting circuit breaker to protect the electrical.
To me it sounds like there is a short somewhere in the wiring that's overloading the breaker and causing the shutdown.

Is it only the headlights that stop working, or do other lights stop working as well?

Remember, the headlights and running lights are the same circuit, so it could be wires on any of them causing the issue.

 

[juanprado]

What kind of headlights are they? Stock sealed beam or led? Aftermarket LED?

 

[Tatsbygreg]

There is an auto resetting circuit breaker to protect the electrical.
To me it sounds like there is a short somewhere in the wiring that's overloading the breaker and causing the shutdown.

Is it only the headlights that stop working, or do other lights stop working as well?

Remember, the headlights and running lights are the same circuit, so it could be wires on any of them causing the issue.

All the lights work until I turn headlights on then they flash on then all lights go off.. ,also on gauge when turn them on looks l iik me a big draw then as soon as they flick off gauge goes back to green

 

[Coug]

All the lights work until I turn headlights on then they flash on then all lights go off.. ,also on gauge when turn them on looks l iik me a big draw then as soon as they flick off gauge goes back to green

So that means you have a short to ground somewhere in the light circuit.

There are a few different ways a short can be looked for, I don't have experience with looking for them in an HMMWV, but first step would likely be just looking at all the different wires you can find for the light circuit and seeing if any of them look like they got warm/got. Opening up all the running and tail lights and pulling out the bulbs to look for issues inside them is also an easy way to start.

After that it's a matter of tracing down all the wires individually to see if any of them are rubbing against something and shorting to ground, or seeing if they are pinched. Up by the headlights would likely be the best place to start as those wires have the most movement due to the hood opening and closing.


Though quick question, did you have this issue before you replaced both headlights and that was why you replaced them, or did it only start after both headlights "went out", which I would assume means burned out. (which in and of itself is kind of suspicious if both failed at the same time)

 

[Tatsbygreg]

So that means you have a short to ground somewhere in the light circuit.

There are a few different ways a short can be looked for, I don't have experience with looking for them in an HMMWV, but first step would likely be just looking at all the different wires you can find for the light circuit and seeing if any of them look like they got warm/got. Opening up all the running and tail lights and pulling out the bulbs to look for issues inside them is also an easy way to start.

After that it's a matter of tracing down all the wires individually to see if any of them are rubbing against something and shorting to ground, or seeing if they are pinched. Up by the headlights would likely be the best place to start as those wires have the most movement due to the hood opening and closing.


Though quick question, did you have this issue before you replaced both headlights and that was why you replaced them, or did it only start after both headlights "went out", which I would assume means burned out. (which in and of itself is kind of suspicious if both failed at the same time)

Ar first one side would come on and off and the other would stay on then they both started coming on and going off so replaced them with leds . Also when they shutoff I can hear a click sound

 

[papakb]

You didn't say whether this happened after you installed a particular component or after you installed all 3 of them. It's always good to go back to the last thing you did when a problem crops up. My recommendation is to reinstall the original 3 lever light and dimmer switches leaving the new headlights and see if the problem still occurs. It's really easy to miswire the headlights. Remember 17 is the high beams, 18 is the low beams, and 91 is the ground lead in the harness. Cheap Chinese LEDs are notoriously crappy and could cause this. If the problem goes away then I would suspect the circuit breaker in the 3 lever light switch. Something else to try would be to cycle the dimmer switch to see if it got miswired. Try switching from high to low (or vice versa) and see if the problem goes away. If it does I would check your dimmer wiring.

 

[Coug]

Ar first one side would come on and off and the other would stay on then they both started coming on and going off so replaced them with leds . Also when they shutoff I can hear a click sound

The shutoff click is the circuit breaker tripping from thermal overload.

One side then the other having issues sounds like bad wire or connection in the hood harness.

Try removing the headlights and seeing what the circuit does. For all you know you got a bad set of lights and one of them is shorted. There is always the chance that you still have the intermittent light issue but are now dealing with bad parts that got installed on top of that.

 

[papakb]

Or you wired one of the hot leads (17 or 1 directly to the 91 ground lead in one headlight.

Check the numbering on the light wires. 17 to 17, 18 to 18, and 91 to 91

There is no #16 in the headlight circuitry.

 

[Tatsbygreg]

Sorry.. thebproblem did start before I changed anything. I've made sure 16 17 and 91 are all in correct places bought new 3 prong after that then new dimmer and also bought a second dimmer . Someone suggested I try removing dimmer and jumping the 91 directly to 17 then try it came one low then back off. When I jumped from 91 to 18 they flickered then back off. I saw there is 2 circuit breakers behind the instrument panel..could it be one of those possibley? Thanks for all the help I really appreciate it

 

[Milcommoguy]

Or you wired one of the hot leads (17 or 1 directly to the 91 ground lead in one headlight.

Check the numbering on the light wires. 17 to 17, 18 to 18, and 91 to 91

There is no #16 in the headlight circuitry.

Told myself to easy up on... ON LINE electrical diagnosis. So am jumping in on this one with MY GUESSessssss.

All things being normal to the truck, no wacky Mr. Edison, Mr. Wizard hook-up, NO non quality add on parts (flicker boxes ??) Then all bets are OFF at this point forward ! **

Best to pull out the prints and follow along. I 'm the little bear with a radio and a map, remember.

Not buying that any lead to the headlight/s can cause a short. Factory Incandescent lamps.

No mater how one hooks it up . Worst case hi/low beam will be squirrel ie. Reason...any lead to any lead has a filament (load) in the circuit. May not be the one you want, but will not create a short. LED's, after market and CHEAP stuff... see second sentence above **.

IF some-um is pointing to a short......

Quick process of elimination. Remove the "HOOD to ENGINE" harness plug. (lower front, left frame rail) Inspect ALL wires, pins for anything unusual (??what is normal) While disconnected, run your test and record results. Still popping breaker...yes um, nope, report.

Using the LIGHTING SWITCH, map out the failure modes and note and report. Does it do it when ?? and which positions. I got it during the headlight
position. What about the other??

Get on hands and knees, (praying) as in a religious act to the Humv Gods and follow all the wires for nicks, scrapes, cut. Pay attention to the rear lighting wires and along frame. Lots of wires exposed to the elements and a GOOD place for damage.

Keep OPEN mind to the whole process AND all the components in play. Guessing from a distant. Could be the switch, could be shorted bulb element (not likely BUT. LED's start another thread) Could be and at this point, could be anything.

BIG GUESS... ditch the LED's and add on's. (12 volt?? flicker box) This is where I ..........

SS guys here could go on and on. Electrical headaches can be, mostly are... unique to your rig. "Shot gunning" can work... but that's not MY way to go.

Divide and conquer the circuit / s to find and repair.

One more and final guess, go back to square one, CAMO

(Sectionalizing is the word, fire extinguisher at the ready)

 

[papakb]

Sounds like it shoulda been a schematic Cam!

 

[Milcommoguy]

HumV's are like a new spelling word... (hang with me a second on this)

One as to see it, say it, learn it correctly, remember it and when the time comes... spell it correctly.

Learn it wrong and likely to spell it wrong, but that can be fixed.

Never learn it, don't care to, or keep trying till it looks write ahh right might work too.

Spell check I guess is the equivalent to Steel Soldiers. Ask someone to look it up for you.

And I am not that guy to mess (different word four letters) with my buds here on SS. OK might give a little poke here in the old shop.

BUT please tell a little more of the story. "Went outside and now it won't start" isn't very helpful.

Doesn't have to read like a Dragnet scrip. Leaving out details turns into a guessing game and it not a crime, but does take up time. ( bear's a poet too)

Having fun with papakb, tobash, a tired horse, a bear and the whole gang. Now there's a story, CAMO

*****************************************************************************
OK back from a commercial break.

Still confused here. So I have questions for YOU.

What is a dimmer in your world? I am guessing the foot switch. Not likely the problem. "FOOT SWITCH DIMMER"
Can you run the lights on the work bench? A little work, but important to know.
Does truck start and run with Lighting switch OFF?
Do you know which breaker is popping?
When adding, replacing or screwing stuff back ... any chance one pinched a wire behind a something or another part. Had to ask

There are three circuits breakers in a basic HumV rig. Two behind the gauges, one in the lighting switch (and you can't get to it easy)
At this point... they are saving your bacon I would do the following.........

Did you remove the hood to engine harness connector and test, then report back. Didn't see a response.

Remove the light switch connector. That will clear up a lot of circuits. Maybe shorted internal somehow?? (never know)

Part of me not clear... are other systems affected or just lighting. Didn't say or I missed that part... me bad.

My last response to this was to break it down. Jump in, stick you nose in there

Sectionalizing by remove circuits so you can to ISOLATE the problem. Voltmeter in hand is handy and knowing how to use it. At least a test light probe. (not meant to be hard words )

Schematic on bench is the road map to success.

Where I am looking to go is down a lighting circuit or engine control / run or accessories. That all for now, CAMO

Double spaced so I can think. Keep the light on papakb

 

[JD4044M]

To pop like that you may have pinched a wire putting the head light in. Pull one out test, till pops the breaker pull the other one and look close at the wire for them.

 

[TOBASH]

OK, I'm gonna weigh in here.

WHAT LIGHT SWITCH ARE YOU USING?

Made in USA? LED or manual?

Are the light bucket electrical connections shorted out?

Break out an ohmmeter and look for shorts with the system off.

If you have an LED light switch, get rid of it. If your switch is not Made in USA, get rid of it.

 

[Tatsbygreg]

What kind of headlights are they? Stock sealed beam or led? Aftermarket LED?

LED

 

[Milcommoguy]

LED

There you go... ONE WORD RESPONSE.

Last and final guess... Cheap Chinezzeam, hooked them up wrong... right out of the box. Now electronics all shorted out.

Remove them and drive during the day,If it even starts. CAMO

 

[Ajax MD]

There you go... ONE WORD RESPONSE.

Last and final guess... Cheap Chinezzeam, hooked them up wrong right out of the box. Now electronics all shorted out.

Remove them and drive during the day, CAMO

Well, I'd plug the old incandescent bulbs in and see if the problem goes away. If the breaker still pops, there's still a wiring problem.

 

[Milcommoguy]

Seventeen quality, thought out responses by the SS platoon.

DONE, CAMO