My headlight switch went out while I was fishing.. went to buy a replacement, Autozone (bleh) and the switch doesn't work. I have to set it in between the notches (pull out in between) to get both headlights AND taillights. Went to replace it with another one, and it's doing the same thing.

1st position, no headlights or tail lights, 2nd position (all the way pulled out), headlights with no taillights or dash lights. 1 1/2 position (between the notches), headlights , dashlights and taillights, 1/2 position, i get taillights and dash lights.

Of course it's probably just a junk switch, but is there any possible way it could be anything else? The switch also gets really hot, but my stock one did as well.
I know it's a dumb question, but if something is grounded out somewhere, some relay is reversed or something dumb I don't want to have to keep replacing headlight switches before I figure it out.

edit: Part Number: SW271 in case anyone else runs into this problem.

 

Headlight switches are internally protected with an auto-resetting circuit breaker on the headlamp circuit. This is the ONLY circuit that does NOT have a separate fuse in the block. If you have increased the headlamp wattage higher than that of the OEM headlamps, you are going to have additional heat and potentially shorten the life of the internal breaker. Otherwise, as long as the connections at each terminal between the harness connector and the switch itself are snug, you should be fine. The harness connector is the most likely culprit if heat is still an issue after replacing the switch.

As to the mis-alignment of contacts for the individual lighting circuits, the only issue it can be is the switch. It is the component that controls what makes contact and in what position. The rest is just wiring and light bulbs.

 

Oh my God, I just got one from OReilleys and it's doing the same fricken thing. I've seen some people complain about the SAME issue but with no real fixes.

1989 F150 Headlight Switch Problem - alt.autos.ford | Google Groups

check this out..

someone once told me that the switch switches grounds, if this is true I might have a theory.. but if it switches 12v, I have no answers.

 

Just curious... which switch did you get from O'Reilly?

Autozone's switch was made by Wells (ugh) according to their website.

I have never had a problem, so far, anyway, with any electrical part made by BWD. The low-line O'Reilly Master Pro part might be made by Wells too.

It sounds like the switch decks of the switch have not been assembled correctly, or their detent mechanism is off tolerance. All you're doing is pushing in your existing shaft into it till it seats, and plugging in the connector. It would seem hard to screw that up, so it's probably the switch.

 

The headlamp switch breaks the HOT (+12VDC) side of the circuit. Negative (ground) (-12VDC) is landed to the frame at a handful of common locations. The switch ALWAYS "makes/breaks" whatever positive (+) voltage it is supplied by the electrical system (Battery & alternator).

Increased heat within the switch but NOT in the wiring is indicative of poor connections of some kind. Loose terminals, corrosion and non-fused additional loads added to the circuits in question are about the only causes. Even the third option would spread the added heat over the length of the wiring run to them but increase heat at common connection points like switch contacts and terminals.

 

It's a BWD.. The Autozone one got warm, but believe it or not, the BWD doesn't at all..

Both times it happened (switch going out) was at a fishing spot that's extremely humid because of the warm water. Both times, I fish, turn on the truck to leave and my headlight switch didn't work. The second time it didn't start working again,l I tore it apart to get it working enough to get me home. Now the replacement is only working at the halfway position.

Just, it seems really unlikely, 3 switches, same symptoms. Two Autozone, one BWD.

I wonder if I shorted something messing with the switch trying to fix it? No single fuse could cause this, I'm just not sure where to even start looking.

Remember, it's both dash and taillights.. do any of you have a pinout and/or wire diagram for the light switch?

 

I'm not too up on the newer trucks, but my '85 did a similar thing. i fiddled around with the switch and nothing seemed to work. After some fortunate accident, I noticed that when I wiggled the floor dimmer switch, it worked fine. I wonder if maybe there is a problem with the dimmer? Just a shot in the dark here, no pun intended.

 

would the dimmer effect dash and taillights at the switch?

 

I'm wondering if I accidently changed the pinout on the harness as well.. willing to look anywhere at this point

 

Mine shut down all the lights. When I replaced it, everything worked fine. I don't know if it carries a common ground or is connected some other way. Like I said, mine was a floor dimmer switch, so if yours in on the column, it may not have anything to do with it. I'm fighting through all sorts of electrical issues with mine right now and am finding a lot of stuff that is connected together, even though the wiring diagrams don't necessarily show it.

 

Well, apparently all I was doing with the switch working halfway out was 'shorting' the switch and giving power to the dome/taillights from the headlight power feed, so a badly built switch just confused me.
I found that there are multiple power supply wires, a seperate one for dome and/tail lights and it was shorted.

See, common sense says I shouldn't get power to tail or dome if there was a short or blown fuse, which is why this was so annoying to troubleshoot. It shouldn't 'sometimes' work or only work under certain conditions.. but because of the weird switch design, I could make them work if I had the stupid switch out halfway.

If anyone runs into this, Tan/White to the switch powers the dash lights and taillights. I found out that it wasn't supplying any power at all.. shorted a wire and blew a fuse in the old switch. At least, I think, haven't replaced the fuse or checked the wire yet.

Sorta glad I went through this though, apparently the Autozone switches only last a few months, this BWD is definitely a better switch AND it was a few bucks cheaper.

 

Cool, I'm glad it was something easy. Did you happen to note what color the wires to the dome/courtesy lights were?

 

The wiring diagram for the main light switch indicates each power feed and which circuit it feeds by tracing the input "line" through the switch diagram to the output "load" side of the switch. The main light switch isn't the only multi-circuit switch in the truck. The ignition switch and the MLPS in newer trucks equipped with the E4OD transmission are both multi-circuit switches. THe reason for multiple circuits is due to the fact that the power feed wiring needed to drive ALL of the lighting circuits at once on ONE feed would create a need for a feed wire nearly the size of a battery cable and a fuse or circuit breaker that could be supplied but the cost would be exorbitant!

 

I'm not sure which is dome light.. black/pink is one of them, don't know if its the feed wire or not though.

And im really surprised at how small the feed wires are, even more surprised at just how much current goes through this switch. I do hope this thread helps someone in the future, saw quite a few with the same problem that never got it fixed.
I think because of the age of the wires im going to put a relay feed to head/taillights, just so I don't have to stress about this switch.

 

I know nothing about this but it looks interesting. It is on sale for $49.
RJM Injection Tech — Headlight Harness