91crew
Full Access Member
The headlights work fine when the highs aren't on. There is no rythm to it. Is this probably my headlight switch?
Headlights flicker on/off when high beams are on
- Thread starter 91crew
- Start date
Russ
Idont do injectors
That would be a goood place to start. The headlight switch is a known weak spot.
DeepRoots
Tug Engineer
I had that happen once. It only happened when highbeams were on.
It ended up being the floor switch.
It ended up being the floor switch.
Double-S-Diesel
parts seller
i say floor switch
Cincinnati Guy
Registered User
Id say floor switch also. Do your dash lights flicker also when on low or high? Does it happen constantly or does it go away with acceleration?
FordGuy100
Registered User
I was driving a 94 IDI and it did the same thing when the high beams were on. And it doesnt have the floor switch 
Sycostang67
Scooty Puff Junior
Thats happened to me twice and both times it was the headlight switch. The headlight switch has a circuit breaker that trips when it overheats(usually caused by the extra draw of the high beams) causing them to go on and off. The foot switch could be the culprit as well, but in my experience it would just cause either the low or high beams to not work at all.
zpd307
Registered User
pull the headlight switch and see how bad it is charred. that should clear up any doubt.
91crew
Full Access Member
I fiddled around with the floor switch and now the flickering stopped 
I guess I have a loose connection around there.
I guess I have a loose connection around there.
DeepRoots
Tug Engineer
yeah, well the floor switch is normally covered by carpet or matting.... and it stays pretty moist.
If it ever gets wet, it stays so for along time.
Best to go pick up an extra from napa and swap it out just in case. They're only a few bucks.
Drew
If it ever gets wet, it stays so for along time.
Best to go pick up an extra from napa and swap it out just in case. They're only a few bucks.
Drew
Papasdiesel
Registered User
Glad I came across this forum. Had a similar issue plaguing my papa. The headlight switched looked new from the outside but inside it was bbq'd. Had it replaced - problem fixed, yay!
Pax vobiscum
Pax vobiscum
Time for the headlight upgrade or lmc kit. Your old switch didn't fry just because it's old. Something caused it and the new one will suffer the same fate.
madpogue
Full Access Member
^^^^^^^ This. The objective is to offload the current load from the cr@ppo factory switches. The LMC product is cheap, but it will achieve this objective. If you want to go a step further and actually boost the voltage going to the lights, get a higher quality relay kit or build your own.
Papasdiesel
Registered User
Well it was 25 years old! We pull a 5th wheel trailer sometimes and I heard and haven't confirmed that the extra draw from the trailer lights caused it? The truck is bone stock except for a few necessities. If I get another 10,15,25 years out of the switch I'm chill with that!
Thanks for the suggestion!
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