Interior Lighting Wiring Schematic

you will have to run NEW wire if you want switch activated lights

Not so if I only want dual function lights. I plan on replacing the stock lights with LEDs and adding blue LEDs as well. Since they are diodes, I will wire them in parallel and have the white LEDs wired with the current polarity of the stock bulb, and have the blue LEDs wired with the opposite polarity (+ on gnd, - on +12v). Then I will use a switch to drive the coil of a small relay with 2 N.O. and 2 N.C. contacts. You wire one input to +12V and the other to ground. Then you wire the N.C. contact on the 12V side to the current 12V wire, and the N.C. contact on the gnd side to the current ground. You then hook the N.O. contact of the 12V side to the N.C. contact of the ground side, and the N.O. contact of the ground side to the N.C. contact of the 12v. So, when you flip the switch, the relay then acts as a polarity reversal switch.

By doing this I can avoid trying to run wire through my roof, but I would like a schematic to be able to properly hook the relay up as to not affect normal lighting function when the switch is off. And also to avoid pulling apart my dash and tracing wires for and hour.

I hope someone can use this little trick to save some time in future electrical adventures

Best you can get from a schematic is the wire color, not where the wire is.
I know nothing that shows where each wire is located in/on the veh.

OK well wire tracing isn't that bad to do, but does anyone have the lighting wiring diagram? The most important thing I'm looking for is HOW it is wired. I need to know the connections to and from the dimmer switch, that way I can select which wire to interrupt and insert the relay and still maintain correct functionality.

Also, does anyone know if they used diodes in the lighting circuit?

Anyone?

I will say something here but I am not familiar with the X's interior lighting so beer (ha ha) with me...

Most interior lighting works on a negative or ground switched circuit, there should be some kind of power at the lights all of the time but no ground per say until a switch is activated completing the circuit.

As far as tracing the wires, it shouldn't be hard to remove the light from its mounting, using a 12 volt probe or multimeter probe a wire, turn on the interior light using the Headlights switch and see what happens, do it to all of the wires (not sure how many are there, until you fine and record all of the info on what is happening at the light; rewire accordingly.

As far as what connections the wires at teh light are the same thing and since you are using LEDs I would believe the existing wire will work.
As far as the added LED, they should be on their own circuit and should not be affected by the existing circuit.

As far as your circuit could you rewrite what you said in the earlier post this old guy to understand, I am confused.

Sorry I can't be of more help.

As far as Diodes at the light or in the light circuit, I wouldn't think so, although the LEDs you are using are Diodes and will only work one way in a circuit.
Diodes are voltage limiting components and I am not sure why they would be in the OEM Circuit anyway.

Thanks for the info! I'll be sure to check that out tomorrow.

As far as the circuit I came up with earlier, you just use a relay and the principle of a diode to make a 2 way circuit with 1 power feed.

Assume the switch is in position 1. In this position, everything is working just like a stock circuit.

Now if you change the switch to position 2, this activates the coil of the relay, and using the wiring as stated before, it acts like a polarity reversal switch. I.E. red and black wires are swapped.

With the switch in position 1, wire the white LEDs exactly like stock bulbs. Now wire the colored LEDs in reverse bias so that they are off in position 1. When you change the switch to position 2, the polarity reverses. The white LEDs cut off and the colored LEDs come on. This allows you to essentially have 2 circuits off of 1 feed without have to run another wire directly from the switch.

Does that make more sense?

An Update

OK so i spent a portion of this 102* day sweating in the X pulling all the lighting fixtures out of the roof. Multimeter in hand, I started to test the functions of the lights.

As I suspected, Ford ran 2 wires for the lights.


There is an 'always on' source at the front and middle dome lights to provide power to the map lights at any time. This wire is Green/Orange, and is the same front and middle. The black piece to the right is this connection


The second wire is the one that is connected to the dimmer. This wire has voltage on it when:
1)The dimmer switch is all the way up in the "on" posistion
2)The dimmer switch is anywhere in the middle (between on and off) and the doors are open.
This wire has NO voltage when:
1)The dimmer switch is in the "off" position
2)The dimmer switch is anywhere in the middle (between on and off) and the doors are closed.
This wire is Black/Blue and is the same in the front, middle, and cargo light fixtures.
This is the connection to the cargo light. It has 3 wires, two Black/Blue connected together at the harness, and a Black (Ground)



The really fun part came when I pulled the front dome light assembly out, complete with thermometer/compass and garage door opener/sunglass holder.

I notice it was connected via a wire harness. I pulled apart the connector and checked it out. It is a 10 pin connector, but only has 8 actual connections in it.

This is the harness that is in the roof.




The pin numbers are labeled inside of the this harness that is connected to the map lights/temp. gauge.
Pin 1 is at the bottom left.
Pin 6 is bottom right.
Pin 7 is top left.
Pin 10 is top right.

The wire colors, pin numbers, and functions are as follows
Pin 1 - No Connection
Pin 2 - Black - Ground
Pin 3 - Gray/Yellow - Temperature gauge/Compass power supply
Pin 4 - Gray/Black - I think this is to the temp. gauge, but i could not discern any effects through testing it.
Pin 5 - Green/Orange - 12V supply to map lights, always on
Pin 6 - Black/Blue - Supply for lights from dimmer switch
Pin 7 - No Connection
Pin 8 - Red/Black - Again I think this is for temp but not sure
Pin 9 - Blue/Yellow - This one is temperature for sure. I was able to change the display by applying differing DC voltages
Pin 10 - Blue/White - Again I think this is for temp but not sure

From what I observed, the digital compass is an internal feature of that circuit, so no input is required. The compass changed directions as I physically moved it, with no connections except for a 12V supply hooked up.

This is the light/compass assembly after removal from the roof. All you have to do to take it off is remove the 2 phillips screws that are inside the garage door opener compartment and pull it off. Don't be scared to give it a little force when taking it off. Just don't try to rip the harness out of the roof in the process


The underside of the assembly. I has several torx screws in it. You need to remove these (7) to remove the map lights and compass from the housing.



This is the cover of the housing. Notice the green plastic cover that goes over the compass/temp gauge. Color change anyone? To get this off, you just have to open the garage door opener compartment and pull down on it. It should pop right off.


What it looks like after the removal of the cover. You have to pull them out this way and not through the back

This is the back side of the map light/compass assembly. The 2 beige little blocks are the switches to the lights. Exactly opposite to them are the buttons that say LAMP. The white wire going into each one is the wire from the dimmer switch. The red/green wires are the ones from the constant 12V source. The black is the ground wire. I will most likely be doing some wiring modifications to this, but I have yet to make any diagrams. The rest of the wires go into the temp/compass circuit.



This is the maximum temperature that the gauge will read. I applied a voltage to Pin 9 to achieve this output.


The lowest temperature is -40 which can be achieved by not applying any voltage. This also shows the actual color of the display. It is a light bluish-green/cyan color, and is a lot brighter without the cover.

Now that I know what all the wires do I will start to design a modified wiring diagram to incorporate a switch and colored LEDs. More info to come later

Good Work and a lot of it...

keep the site informed of what you do.

Great pictures and instructions!! Helped me with another project!!

Dave

An excellent reason to become an Elite Explorer. This information and help is priceless to us who are car/truck/light guys.
Nice way to say thanks if you can.

2000 Explorer Eddie Bauer

I have an issue with my compass. I have tried to reset numorous and I get nothing. I need to know where else to start to find the problem so I can get my compass to work again.

Well thats gonna be a tricky one to figure out. I don't have a schematic of the circuit they use for the compass, and I also don't have a scope, so it would be rather hard to diagnose. As best as I remember from when I was fooling around with this, the compass is all integrated in the overhead console, as I got it to work while not being attached to the explorer.

What exactly is your problem? Does the compass show the wrong direction? Does it fail to show up at all? Is your temperature gauge still working?

Does anyone happen to know where the group of wires in the roof harness run to? The previous owner had the lights/compass disabled by a mechanic, but I checked it out and all the wiring in the unit are intact, so I would like to have it operational.

Pin 8 causes the overhead temperature display to dim when the headlight switch is turned on to any mode. I had the issue where I didn’t want this to happen since I run my parking lights in the day and a dim temperature display isn’t great in daylight. So I just cut the red/black wire on pin 8 and the display is always bright now, when on.

greyphox said:

View attachment 48615
View attachment 48616
This is the back side of the map light/compass assembly. The 2 beige little blocks are the switches to the lights. Exactly opposite to them are the buttons that say LAMP. The white wire going into each one is the wire from the dimmer switch. The red/green wires are the ones from the constant 12V source. The black is the ground wire. I will most likely be doing some wiring modifications to this, but I have yet to make any diagrams. The rest of the wires go into the temp/compass circuit.


View attachment 48617
This is the maximum temperature that the gauge will read. I applied a voltage to Pin 9 to achieve this output.

View attachment 48618
The lowest temperature is -40 which can be achieved by not applying any voltage. This also shows the actual color of the display. It is a light bluish-green/cyan color, and is a lot brighter without the cover.

Now that I know what all the wires do I will start to design a modified wiring diagram to incorporate a switch and colored LEDs. More info to come later

Click to expand...

How much you want for the unit