Skip to main content ↑ ↓
Topic: Headlight Switch Overheating (Read 7117 times) previous topic - next topic

Headlight Switch Overheating

Reply #30 –
Sluggo Very true.

Now, what I mean by all I posted above is this.

Even though the contacts in the switch are still the same size, the headlamps would be wired with power comming directly from the battery, instead of pulling it through the switch.  that means with less power actually being drawn through that switch, the thermal problem should be solved.  IN ADDITION to all of that, it would not be a bad idea to get new plugs and pigtails for the light connectors.  They (along with that switch) are notorious for failure.  Ive seen more than my share of headlight plugs actually melt, and some actualy burn because higher than stock wattage bulbs are being used.  Usually the problem with the switch is a on off on off switching when the breaker re-sets itself because of too much power being drawn through it.    basicly, the contacts are moot because there is less of a power draw on them.  I used the NATO tech article to accomplish the same thing, because of the same problem.  The only drawback is that the systems sentry always shows a " low beam out" light on because the draw isnt enough to keep it happy. 

"Why? If you suffer from worn out headlight switch circuit breakers, headlights going out for no apparent reason, and you have tested and reground the entire electrical system, this mod is for you! Ford designed the headlight switch so that all current for the headlights high and low beam) and fog lights runs through the headlight switch. There is a self-resetting circuit breaker in loop, that tends to wear out. Also, if you run a non-stock headlight bulb, this circuit breaker will wear out faster, since there is typically more current drawn for the non-stock bulb."

This also causes the stock switch to be hot or warm to the touch.

It makes sense if you read the article.

26. I just finished this on my own 88 TC. I ran the car for an hour afterward with the high beams, low beams and fog lights on, and switch never got even warm. Prior to this mod, my switch would get really warm after the headlights had been on about 20 minutes. The only problem (if you want to call it a problem) is the "Low Beam Out" indicator on my system sentry panel illuminates when I turn the headlights to low beam. I guess the circuit is not drawing enough amps through the switch to keep the computer happy.

and that part basicly says what Ive said here.

Switch never gets hot, lights dont cut out, and everything is happy fine...(except the systems sentry)

Jcassity:  I didnt mean just you, and I didnt mean to imply that you were "Just Bitching about NATO"  I was just trying to get everyone back on topic, and help solve a problem for a board member.  Isnt that what we are all here for anyways? :) 
If you've never been to the board before, have you ever read that particular tech article?  If not...... and i'm really not trying to be a dick..... I woulndt have made your first comment.  Thats just me.  I would have read it  and then after checking it out commented one way or the other.  I fyou have read it and you see something wrong, then post up some helpful info to get our member's problem fixed. 

And Santana, its not the contacts that cause the on off on off operation. Its the self resetting circuit breaer in the loop. that breaker wears out, and can be very touchey.

I dont mean to piss people off here, and i respect most on this board that ive had the pleasure of helping and being helped by (Jcassity you are included in this bunch) I just want everyone to have an open mind and to help our fellow member.  This is a great community, lets keep it that way. :)
88 TC, Lots of Mods.

Headlight Switch Overheating

Reply #31 –
Quote from: Birdman;183564


"Why? If you suffer from worn out headlight switch circuit breakers, headlights going out for no apparent reason, and you have tested and reground the entire electrical system, this mod is for you! Ford designed the headlight switch so that all current for the headlights high and low beam) and fog lights runs through the headlight switch. There is a self-resetting circuit breaker in loop, that tends to wear out. Also, if you run a non-stock headlight bulb, this circuit breaker will wear out faster, since there is typically more current drawn for the non-stock bulb."


hummm.....................

ok,, ill bite.
where is the headlamp breaker?  never seen it nor do i think i ever will.  Our main light switch is fuse link fed.,,not breaker controled.

Besides,,, the heat producer in the switch is the dimmer variable resistor imho.  I experimented and found out if i run down the road with my dome light on, that the switch is cooler.  You can see in the drawing that when the dimmer wiper arm is moved to the left, you are in max current / least resistance.  Imho, as soon as you reach that state of near zero ohms, the "load"(dimmmer rherostat) is not "absorbing: current in the windings therefore not producing joules of energy in watts or power.
thats just my opinion but at best, my test actually showed the switch got cooler when you rotate the dimmer so the dash was at max intensity or as well, with dome on.

I just dont see a circuit breaker anywhere.

Headlight Switch Overheating

Reply #32 –
I believe this "circuit breaker" is a thermal switch inside the light switch assembly.  Could I be wrong?

Headlight Switch Overheating

Reply #33 –
Birdman 2 thumbs up on correcting my mistake and letting me know about it so I do not make it again. Thanks.

Headlight Switch Overheating

Reply #34 –
Quote from: Sluggo;183693
I believe this "circuit breaker" is a thermal switch inside the light switch assembly.  Could I be wrong?


no one here has ever as far as i know mentioned a circuit breaker in the switch.  Im still waiting on a response to that part.  I dont have an extra one to disect though so maybe someone else could confirm.

I may dig into that subject using my shop manuals tomorrow while i get some spare time.

Headlight Switch Overheating

Reply #35 –
Sorry, my net was down for a bit. I beleive that it is part of the switch Like sluggo said. I guess its a thermal switch, not exactly a breaker. 

thats interesting what you posted about the dome light though. I think this may warrent some more investigation.
88 TC, Lots of Mods.

Headlight Switch Overheating

Reply #36 –
On the main light switch, the connection between B1 and B3 is the symbol for a circuit breaker.

Headlight Switch Overheating

Reply #37 –
Well I haven't had time to do much yet except check the fog light wiring.  Thanks for posting the wiring diagram.  I actually have that book somewhere.  Anyway the company I ordered the switch from emailed me that they don't have it anymore and its discontinued, but I have a lead on one.  About the autolamp option I don't have it.  And I can confirm that inside my switch there is a metal strip that bends away from its contact when it gets hot.  Also to be clear there is two different switches that come up for my car in the parts stores computer systems.  One they have in stock and its only like 25 bucks or so.  The other is the one I have and is much more expensive, but discontinued.  Tomorrow I'm going to call a place in another state that shows has having one in their inventory.

Headlight Switch Overheating

Reply #38 –
is this what everyone means by triggering a headlamp circuit?

I attempted to compare what effects this would have on an autolamp system and it just got kind of lost in my current beer:D 

 I suppose the fuse link that feeds the switch becomes a little over kill now eh?

Headlight Switch Overheating

Reply #39 –
Quote from: jcassity;184810
is this what everyone means by triggering a headlamp circuit?

I attempted to compare what effects this would have on an autolamp system and it just got kind of lost in my current beer:D 

 I suppose the fuse link that feeds the switch becomes a little over kill now eh?


Look at your EVTM on page 81.
The headlight circuit for the autolamp feature uses the circuit breaker that is built into the main headlight switch.

Hot at all times comes into the main switch on B1, through the circuit breaker and out on B3 to the autolamp relay #1.

Headlight Switch Overheating

Reply #40 –
yeah, i wasnt talking about that part,, im talking about the contact side of the secondary relay.

anyway, does this look reasonable for those without (vast majority) without autolamp?

Headlight Switch Overheating

Reply #41 –
Quote from: jcassity;184925
yeah, i wasnt talking about that part,, im talking about the contact side of the secondary relay.

anyway, does this look reasonable for those without (vast majority) without autolamp?



That does look like what they are talking about.

The fuse linked wire that feeds the switch is not unique to the light switch. It also feeds fuses on the fuse panel. It protects the wire between the starter solenoid and the fuse panel/ light switch.

Headlight Switch Overheating

Reply #42 –
Quote from: softtouch;184966
That does look like what they are talking about.
.


I didnt see a thread to a link i could compare to.  I just dont know what rating should be on the relay, the fuse feeding the relay and the fuse inline with the coil.
Im thinking,,,,,,,,,

30A feeding the relay contacts to power headlamps
10a feeding the relay coil


honestly,, i think those ampacities are excessive except for the fuse feeding the new relay contacts.  Evidently the front park lamps are 15a while the tail end with all the multipule bulbs in parallel is 10a.

there is something wrong with this but i cant quite put my finger on it just yet.  I gotta have it layed out with several diagrams layed out infront of me at once.

 Notice that jumper i have from the park lamp position???

Headlight Switch Overheating

Reply #43 –
Quote from: jcassity;184991
I didnt see a thread to a link i could compare to.  I just dont know what rating should be on the relay, the fuse feeding the relay and the fuse inline with the coil.
Im thinking,,,,,,,,,

39A feeding the relay contacts to power headlamps
10a feeding the relay coil
15A relay

honestly,, i think those ampacities are excessive except for the fuse feeding the new relay contacts.  Evidently the front park lamps are 15a while the tail end with all the multipule bulbs in parallel is 10a.

there is something wrong with this but i cant quite put my finger on it just yet.  I gotta have it layed out with several diagrams layed out infront of me at once.

 Notice that jumper i have from the park lamp position???


Remove the jumper, otherwise you will have the headlights coming on with the switch in the park position.

Fuse sizes are determined by what size wire you are protecting.

I don't know how many amps the headlights draw.

Headlight Switch Overheating

Reply #44 –
i suppose there really isnt any way around not using two relays at the least , one for the park lamps and the other for the headlamps.