Witch wires should have power/ Map switch

[hoop]

Just wondering if this is right befour I put my map light switch in on the 72 dart!.... Witch wire should have power on map light switch, the brown has power all the time, the yellow has power when dome light is off & has no power when dome light is on, so douse this seem right?

 

[67Dart273]

I hate this circuit, and since "I don't have one" I really don't have it figured. It's a mess, tied in with the time delay, and the multi-pin door switch on the left side.

You have the 72 shop manual?

In the underdash harness the main harness accessory connector M2 series wire goes up and eventually ties in at the headlight switch terminal of the dome light switch (twist the knob to left) and GROUNDS that yellow

The M6 series yellow goes over and connects to the left side multi terminal door switch, shown in the bottom drawing.

In the top drawing, start at the map light and follow over to the right to B of the time delay, then, M3018P and notice that connects to the "cigar lighter connector" of the main harness THIS IS where 12V hot power is coming in

Then I BELIEVE that the map light switch is a single pole double throw TO GROUND, so the switch I believe must be grounded. I would bet if you unplug the harness from the switch, and check continuity to the switch mounting, one postion of the switch will show continuity to one of the pins, probably the M12BR pin. (brown)

I believe that the M2C wire (yellow) going off is simply tied to the left door switch and turns the lamp one with door open. I could be mistaken.

The PROBLEM is the time delay, as I have no idea what it's internal wiring is or does.

 

[D Cluley]

The '74 manual makes some of this clearer, and confirms the information from 67Dart273.

Basically, if the headlight switch is turned, or if either door is openned, then all the yellow wires are connected to ground, and the lights come on.

The brown wire goes from the switch to the map light socket.

With the switch in the normal position the brown and yellow wires are connected and the map light comes on with the dome light.

With the switch in the other position the brown wire is connected directly to the switch body which grounds to the dash frame and the map light comes on even if the dome is off.

--------------

As for the time delay thing, Yeah, I think its magic. ;)

I suspect it's a combination of a relay that is energized by the yellow ground wire and either a capacitor or something thermally controlled that keeps it energized briefly after the dome light goes off.

I have noticed that the longer the dome is on, the longer the ignition light stays lit after the dome goes off, that makes me suspect it's a capacitor, but I don't really know.

 

[67Dart273]

Thanks for the additional

 

[D Cluley]

No problem, when I got mine the switch was broken, and I had to figure out how to replace it with a regular hardware store toggle.

Now I'm curious about that time delay thing, but don't think I'm going to pay ebay prices to take one apart!

 

[67Dart273]

The delay thing is solved with your diagram, as is the map light switch, as the 74 diagram shows the internal wireing

All of the Pink is power to the lamps and right side of the delay relay

Left side of the delay relay goes to the ignition lamp. When you open the door, this grounds the HEATER in the delay relay, and causes the bimetal strip in the relay to close the relay, holding the ignition switch lamp on

The map light switch is shown "OFF" and is brought on by the door switches with the rest of the dome/ courtesy lamps. When the switch is "on" the wiper rotates to the "ground" terminal and turns the map light on directly.

But the OP hasn't been back, so who knows??

 

[D Cluley]

That makes sense, don't know why I didn't see it last night. Hopefully we helped the OP, but at the least we learned something, right?

The wiring on my '65 is a lot less complicated, but the '74 FSM diagram is SO much more detailed.

 

[67Dart273]

74's are also different in many ways from the 72, don't have a 73 so can't comment there.

 

[hoop]

Mmm I was hopein someone would have tested thear map light switch befour to see witch wire had votes & give me a simple yes or no, It douse sound like the switch has to be in place wear it should be, not just toch up aginst a unpanted part of the dash for it to work, yell I'm just traying to figer out about the switch on my parts car I took off & tested on mine, I was just wondering did I mess it up or was is all ready bad, bacause I got another one thats post to be good & I did not wont to do anything to mess it up.

 

[D Cluley]

The brown wire will have power all the time if there is a good bulb in the map light socket.

If the dome light is on (either turning the headlight knob, or with a door open) the yellow wire will be connected to ground, if the dome light is off, then the yellow wire should show some positive voltage because it's feeding through the dome light bulb.

To check the dash wiring without the switch plugged in:

Connect the brown wire to ground, the map light should light up.

Connect the yellow wire to ground, and the dome light should light up.


To check a switch out of the car:

With the switch in the normal position (the map light goes on/off with the dome light) the two prongs on the switch should have continuity.

With the switch in the map light always on position, the prong for the brown wire will have continuity to the metal body of the switch, and the prong for the yellow wire doesn't have continuity to anything.