Allow my headlights only to turn on and stay on only while the engine is running? I have a 96 f150 Eddie Bauer and the previous owner cut off the harness that sounds the warning buzzer when they're left on. I have had to jump the battery 3 times now because I forget they're on. Wondering if I could install something that would only allow them to be on only when the engine is running, and turn off when I shut the engine off. FTR, I wouldn't mind if automatically turned on whenever the engine was running - even during the day.

 

I don't see why you couldn't cut the wire feeding the headlight switch that is hot all the time and feed it From a circuit that is only hot with the key on. You would need to use relays so you don't overload the new power source.

 

You could definitely go the relay route. But another option would be to fix or replace the warning buzzer. I bought a headlight warning buzzer at NAPA and put it in my '71 Bronco. That was cheap and easy.

And for what it's worth, I would want to be able to turn the headlights off rather than have them on always. Starting with the battery low would be one reason. Sitting at night at times would be another.

 

You could add a relay in addition to the existing headlight switch. Lights would always be off when key is off. When key is on, switch acts normally.

I wouldn't depend on the relay to turn off your lights all the time, I would use it as a failsafe when you forget to turn off the lights yourself. You don't want the lights burning when you're trying to start the truck on a cold morning.

 

If I were wiring my lights to only be on when the engine is running I'd leave the light switch and it's wiring alone, and make all the changes under the hood.

I'd get three relays. On the first one I'd find a wire that's hot with the engine running for the control, and I'd run a wire directly from the hot side of the starter solenoid through an in-line fuse to the switch side of the relay.

I'd run the output of this relay to the switch side of both of the other two relays. On one of them I'd take the control wire from the low beam wire at one of the headlights and use the high beam wire to control the third relay. Then take the output of these two relays to the low and high beam at both headlights.

One thing I haven't completely thought through is the running lights. Changing the wiring at the switch would deal with that. But I'm sure it could be figured out my way as well (I'm just too tired to try to do it right now).

My way also has the disadvantage of relying on the relays to feed the lights. If the relays go bad you won't have any lights.

However, the advantages are that you don't have to hack up the wiring under the dash where it's harder to get at. And more than that, it gets maximum voltage to the lights. I did something like this on my sons Cherokee (but without the first relay so the lights work normally with the switch). His lights were so dim I was thinking only the running lights were on when really the low beams were on. He only had 10V at the lights with the engine running. The relays made the lights a ton brighter. Not saying your headlight wiring is as bad as his was. But if I was doing relays I'd do it like that to get the brightest headlights I could

 

My headlights are not very bright, so maybe this would kill two birds with one stone. Since I know nothing about electronics ( I don't even know what a realy is), I'll have to stop over to my dads and have him help me. I do have the Ford service manuals, so I'm sure he'll be able to find the wiring diagrams and such.

 

this may sound harsh but the cheapest way to fix this would be to check to make sure your headlights aren't on. my headlight buzzer doesnt work either, cuase its unplugged

 

Whiter Whites, Brighter Brights .: Articles

That should explain what the relays do. You can also buy a relay kit that is plug and play from several places, the name escapes me right now.

 

Well, I thought I would be able to do this, but after 3 times, it's apparent that I can't remember. All 3 times happened on longer drives in the early morning, when it was dark when I started, and light when I arrived at my destination. I just didn't notice the lights were still on. I just don't have the memory in my old age that I used to!!!

 

i hear ya on that one, i have walked all the way to the door in the morning and see the headlights reflecting on the door window and still didnt register that the lights were on lol

 

I should add that if it were my truck I'd either fix the original warning buzzer or add an aftermarket one long before I looked at making the lights go out when the engine is off. You can still do the relays to make the lights brighter, but that's simpler if you don't need to deal with the running lights anyway.

 

Yeah, I think this is the route I'll go. I did not realize you could get aftermarket buzzers with the wiring and stuff, so I'll do that, and then do the relays for brighter lights.

 

did the original owner physically cut he buzzer out or just un clip it from the connector? i have mine layin around that is never going back in it, i cant stand those things, especially when both doors are open and music is on and it sits there chiming

 

I grew up in an area where we left the keys in the vehicles, so when you get out the buzzer was going off. I guess I'm one tone deaf to it, the buzzer does me no good. Some imports, Subaru comes to mind are wired where the headlights shut off with the key. I don't know why they aren't all like that... Maybe it's some dot regulation or something.

 

My 93 toyota shuts them off after I open and close my drivers door with the ignition off. Don't think I have turned off the switch in 10 years. I still leave my keys in the ford but,,,,,,,,,,,,,, I cant ignore that awful buzzer! Most disruptive sucker I have heard to date.