Headlight Switch Schematic

[mydart270]

does anybody have a schematic for the internal connections on a headlight sw installed on a 1968 Dodge Dart 2 DR H/T?? This makes it very easy to trace wires when sw is in middle position and full-out position.

the reason i would like to know is as follows: I have no headlights in the full-out position and IGN is OFF. I do have BRAKE, TAIL, and Marker. Perhaps a short causing the internal ckt breaker to open (why doesn't it close after 30 seconds). Anyhow will t/s on Thursday. With IGN ON all lights operate including headlights......dah!!!!!!!!!!!

Thx again...great Forum.

 

[67Dart273]

The headlight switch is actually two or three switches in one box, with TWO battery supplies

B1 is UNFUSED and supplies ONLY the headlights. It comes from the ammeter circuit When the switch is "full out" that sends power ONLY to the dimmer switch and no where else

B2 is fused power from the tail fuse from the fuse panel.

It powers the tail/ park, and instrument lamps


There are TWO terminals it feeds out.......one is for park "P", which is ONLY powered in "park."

the terminal for the rear lamps "R"is powered BOTH in park and head. THAT terminal is what Ma switched the park/ marker lamps over to in 68/9/later to keep the park and marker lights on in the head position

Internally, the park/ tail switch also feeds power to the dash dimmer control. That feeds out (on TAN) TO the instrument fuse on the end of the fuse panel. From there, dash lamp power goes out on ORANGE wire

Replacement switches for most these cars should be available at your "corner" half assed used to be known as an "auto parts store"

B1.........power to switch from ammeter circuit for HEADlights only
B2.........power to switch from tail fuse

P............feed from switch to front park lamps
R............feed from switch to to rear tail lamps

D...........Dome light switch......Grounds the yellow when knob twisted left

H...........Feed from switch to headlamps

E1-18T...Improperly marked is the output of the dash dimmer feeding "dimmed" power down to the iNST fuse

 

[67Dart273]

So in 'HEAD'

you have power.......

From B1...........to H

And from B2.......to R......and the TAN "dimmer."
=============================

In "Park" you have power from B2.......toR.......toP.....and to the TAN

 

[mydart270]

So in 'HEAD'

you have power.......

From B1...........to H

And from B2.......to R......and the TAN "dimmer."
=============================

In "Park" you have power from B2.......toR.......toP.....and to the TAN

Thank you...Thank you....Thank you. You guys are the best. The more I get into this old car/restoration thing, the more confusing it gets. Thx for people who love 50 year old Dodge Darts. Have a great July 4th

 

[mydart270]

So in 'HEAD'

you have power.......

From B1...........to H

And from B2.......to R......and the TAN "dimmer."
=============================

In "Park" you have power from B2.......toR.......toP.....and to the TAN

Thank you...Thank you....Thank you. You guys are the best. The more I get into this old car/restoration thing, the more confusing it gets. Thx for people who love 50 year old Dodge Darts. Have a great July 4th

One more question... tell me about this internal ckt breaker? Its thermal as I understand and when does it operate? Also does it reset correctly or go into a "la-la" state where connectivity is compromised?
Thx again....

 

[RedFish]

That circuit breaker is bi metal. It bows as it overheats which opens contacts. So it should cycle some number of of times before it breaks completely.

 

[mydart270]

That circuit breaker is bi metal. It bows as it overheats which opens contacts. So it should cycle some number of of times before it breaks completely.

thx RedFish..great knowledge you have. People told me about a spring but your description is more accurate. Have a great July 4th.

 

[67Dart273]

^^All such breakers are basically thermal. Something you need to be aware of is that HEAT caused by something like a contact going bad in the switch or a bad wire connection at the connector can radiate / conduct enough heat to cause the breaker to cycle. In other words "there is a problem" but it's not from high current.

On a side note I've seen guys put things like aftermarket breakers for trailer brakes CLOSE TO THE engine, and the engine heat degrades their amp rating!!!

 

[Davidrad]

Sorry to tack onto an old thread. I've gone through a few headlight switches after getting this 70 Dart ok the road. There must be a root cause I don't see the spade terminal that sticks out the back on the diagrams. Is it a ground for the switch? And if so that may be why i lose my lights.

 

[RedFish]

Sorry to tack onto an old thread. I've gone through a few headlight switches after getting this 70 Dart ok the road. There must be a root cause I don't see the spade terminal that sticks out the back on the diagrams. Is it a ground for the switch? And if so that may be why i lose my lights.

That spade terminal for a ground wire wasn't present on early OEM switches. They mounted in metal and got the ground there. It is found on all newer switches so one size/type fits all. Adding a ground wire here can't do any harm but... there isn't much benefit either. Improved chassis ground for instrument panel in general. Only part of lighting circuits grounded at this switch is the dome lamp. all other current paths are in on one terminal and out on another. Ground happens beyond the bulbs.

 

[67Dart273]

Things to check. Check CAREFULLY the condition of the terminals in the switch connector. They may be loose causing heating and damaging the terminals, and conducting heat into the switch.

Make certain the switch is actually getting power at B1. You may have an intermittent connection there. That wire joins the black ammeter wire at the "Great Big Welded Splice" and those can and do fail. Wiggle the harness while having someone watch the headlights when on

Go over and check the path to the headlights..........the dimmer switch connector and the dimmer switch, and the condition of the bulkhead connector terminals

What are you using for headlights? Are they much higher wattage than originals?

There is the very real possibility that you keep getting "modern Chineseoationized replacements which are crap. Before I tore my car down, I had bought an NAPA dimmer switch. It lasted about 20 "stomps" before falling apart. I don't drive much at night

 

[Mattax]

If nothing obvious after doing what was just recommended above, check at the headlights themselves.
The connector on the back of the lamps can have similar issues.
I also had an instance where the wire insulation had chafed against the headlight bucket. Once that happened, the circuit breaker would open whenever the wire grounded.

 

[Davidrad]

I think it has to do with my new powder coated dash frame. I'll run a ground to that back terminal and see if it helps.

 

[67Dart273]

I think it has to do with my new powder coated dash frame. I'll run a ground to that back terminal and see if it helps.

The ONLY thing that ground would affect is the dome light switch in the light switch AKA "twist the knob to the left" to energize the dome lights. It grounds the switch leg, same as the door switches.

If something else in lights is not working, that ground is not the problemo

 

[Davidrad]

Darn. I can't find why I keep blowing switches.

 

[67Dart273]

Well maybe you are not. But if you are actually "blowing switches" it is likely one of two or three causes. One might be that the terminals in the harness connector are failing and loose. This will cause poor connections which will cause heating, and transfer that heat into the switch. Eventually this will fail the switch.

Another might be a short or partial short in the headlights circuit.

Or it might be that it's not the switch at all.

Headlights are quite simple. You have two power sources to the switch and it is in reality, 3 separate switches, or maybe 4 depending on how you look at this, in "one box"

One power source powers ONLY the headlights. that part of the switch is completely separate from the tail/ park and dash lights That is "B1", feeds through the switch, off to the dimmer switch, and then out through the bulkhead connector via the hi and lo beam wires to the lamps

The second comes from the tail fuse and powers the tail/ park and dash lamps. The park lights wire got moved in later years from the park lights terminal of the switch to the tail lights terminal, so the park lights stay on with the tail lights at all times, unlike my 67 where the park lights are only on "in park."

This same power source poweres the dash light dimmer, and that "dimmed" pwer goes out of the siwtch to the fuse panel, to the "INST" fuse, and then on to all the dash lamps.

Simple. Break it down into what it does, find out what works/ does not work, and troubleshoot it.

 

[Davidrad]

It's the headlight power only. I have everything else every time it blows. I've checked everything in that circuit. I think I'll put an in line fuse after the switch and before the bulkhead connector and between the bulkhead connector and the closest headlight and another fuse between headlights. That way I'll be able to diagnose the area it's coming from.

 

[RedFish]

It's the headlight power only. I have everything else every time it blows. I've checked everything in that circuit. I think I'll put an in line fuse after the switch and before the bulkhead connector and between the bulkhead connector and the closest headlight and another fuse between headlights. That way I'll be able to diagnose the area it's coming from.

I would have a close look at dimmer switch and its wiring. I've been talking with another owner over the phone who found a melted wire casing there.

 

[Mattax]

Do you have an ohmeter or continuity checker?
That will be easier than wiring in fuse holders.
Remove the connector at the dimmer switch and check for continuity to ground for each of the thee wires.
If the headlight switch connector is easier for you, could start there instead. Doesn't really matter.

With the headlights connected, there will be some continuity to ground.
If its zero there's a short. If its above zero, disconnect the headlights.

That will also be an opportunity to check the wire condition in the buckets.
Light green was often used for the wire from the headlight switch.

 

[Mattax]

I would have a close look at dimmer switch and its wiring. I've been talking with another owner over the phone who found a melted wire casing there.

Maybe I need more coffee.
Something none of us asked yet.
What headlights?
1970 would have come with 6012 which nominally drew something like 50 Watts.
A lot of replacements draw more than.

If its not a short, but damaged wires or connections, then installing a relay system is a good solution.
You can make your own or buy a premade plug and play harness.
For the premade, get a quality one like Crackedback makes and sells.
For make your own, you can get parts from Dan Stern if you dont want to hunt your own.

 

[67Dart273]

^^I almost brought this up^^ But as I said earlier, if the switch is actually failing, it either has to be something causing heat (bad connection) or some sort of short, or something drawing too much current.

 

[Davidrad]

Maybe I need more coffee.
Something none of us asked yet.
What headlights?
1970 would have come with 6012 which nominally drew something like 50 Watts.
A lot of replacements draw more than.

If its not a short, but damaged wires or connections, then installing a relay system is a good solution.
You can make your own or buy a premade plug and play harness.
For the premade, get a quality one like Crackedback makes and sells.
For make your own, you can get parts from Dan Stern if you dont want to hunt your own.

They are 6014

 

[Mattax]

They are 6014

The incandescent version
60 Watt Hi/ 50 Watt Lo

6012 were 50/40

Not a big difference but a difference on a marginal circuit.
I had problems with my '75 in '85. Circuit breaker tripped off on the interstate. Took the lamps out thinking they were blown. Nope.

 

[Davidrad]

So I spent some time ohming everything out and I had continuity where it should be. I decided to plug back in the headlight switch and mess with it a bit. After pulling hard on the handle I got the headlights for a moment then some arcing noise and then it all went dead. Then I'd pull again and more arching and everything came back. I started feeling around and found that the b1 wire on the connector was hot. Which makes me think it's drawing too much due to something or other.

 

[67Dart273]

So I spent some time ohming everything out and I had continuity where it should be. I decided to plug back in the headlight switch and mess with it a bit. After pulling hard on the handle I got the headlights for a moment then some arcing noise and then it all went dead. Then I'd pull again and more arching and everything came back. I started feeling around and found that the b1 wire on the connector was hot. Which makes me think it's drawing too much due to something or other.

That might be but ..........I think the opposite. Go re-read what I posted earlier. You said you failed more than one switch. "I bet" the b1 connection IN THE HARNESS CONNECTOR is fubar and arcing and conducting heat into the switch

Something you need to be aware of is that HEAT caused by something like a contact going bad in the switch or a bad wire connection at the connector can radiate / conduct enough heat to cause the breaker to cycle. In other words "there is a problem" but it's not from high current.