Once in awhile at night my headlights go out. tonight they went out four times. Just the headlights,all the instrument cluster and marker and tail lamps stay on during this gremlin. Each Time I pulled over and flashed my hazard and the Headlamps came back on within 30 secondsThe plugs on the back of each lamp passed the tug test and the grounds on the innerfender looked great.

Sounds to me like maybe my headlight switch is dying. Of course when I got home a jiggled and tugged on the switch it did not respond as planned and the light stayed on.

And one time they went out when I hit button to go to hibeam,hit the button again for lowbeam and nothing until a few seconds passed.

Something that turns off my headlight and leaves me in parking light mode,what guesses do y'all have

 

The headlight switch has a self-resetting circuit breaker that could be doing its job; you say the grounds look good, how about the connections to the headlamps themselves?

If all of that is in good shape, I would discount the possibility there's a melted wire behind the dash (tan & white I believe) as that thing overheats and melts as a result of too much heat which results from bad connections at the headlamps combined with barely-adequate wiring Ford gave us.

Instead of that, I'd focus on the dimmer switch on the floor....

 

Can you hear a click when the breaker resets?

Many of us have mounted a pair of relays under the hood to provide full current to the headlamps and take the load off the already feeble wiring feeding the headlamp switch.

 

I consulted the Chiltons the morning and saw no breakers in the diagram,and I did not hear anything when the lights came on...based on diagram I think either the dash/floor is suspect...more so the dimmer

 

The breaker is in the headlight *switch* not in the wiring.
Aftermarket manuals are known for their crappy schematics.
An EVTM is really your best resource when trying to troubleshoot these problems because all tests are detailed in the order they should be performed.

 

Call me Mr. Vegas, but I'd be willing to bet one of your headlight bulbs is drawing too much current. As previously mentioned, the automatic circuit breaker in the headlight switch is doing its job. Take an amperage reading on the bulbs if you'd like, but I'd probably just swap them both out and see what happens.

As far as the dimmer switch, a typical failure there is pitting on the contacts creating extra resistance in series with the bulbs, and thus lower current flow. That would be the opposite of what you are experiencing if the auto CB is cycling. I'd lean first towards a faulty bulb.

Speaking of the old-school foot-operated dimmer switch on the floor, have you heard some manufacturers may be going back to that, instead of the newer style switch on the steering column? It has to do with lawsuits. Too many people were getting their foot caught in the steering wheel.

Rimshot, please!

 

Similar problem with my '81. Hi-beam switch on the floor or the plug. I haven't replaced anything being I hardly drive the thing and never at nite. I just jiggle it a bit and it holds.

 

Three votes for the switch or the wiring going to it.
Pulling back the mat and cleaning up the contacts is simple.
You can ohm out the high and low circuits from there.

 

Thanks for the pointers. I do not evtm,and my book does not give ohm specs for the dimmer. Lights did not go off once last night. I hate intermittant problems

 

You're ohming out the *load* side.
What wattage headlamp bulbs do you have, 55lo/60hi ?
So add the two head lamps together and use ohms law to figure out how much draw is on the switch.
I=V/R
ETA: Use 14V because that is about what the system will see while the alternator is charging.

 

The floor dimmer is only a pass thru switch so if the low beams go out because the main switch tripped then no hi beam either.


Now it would not hurt to check the wiring at the dimmer but my guess is if you find corrosion at the plug it will also find its way up inside the wires and this will raise the resistance and pop the breaker. They only way to find the corrosion inside the wires is to open them up.


After you find the cause of the high resistance replace the head light switch as the breaker gets weak from tripping all the time. It could be it is just weak too.


I remember a 68 Ford wagon we had that would trip the breaker only when pulling the travel trailer. Replaced the switch and never an issue again. Weak breaker in switch.
Dave ----

 

1984 Ford f150 for sale. Runs good,headlights optional

 

The quick way to see the problem is perform a voltage drop test.

Ohms test won't tell much. With headlights ON place one voltmeter probe on the negative battery post and the other on the ground blade of the headlight.

Ideally you'll see Zero volts but whatever the voltage, is the amount being LOST in the corrosion and connections. 0.2 volts is the limit, same for positive side. This voltage drop will roast switches. Clean grounds and connections = Happy electrons.