Dimmer Switch problems?

[aaronajb1981]

So on my way to work today, i used the dimer switch to turn on the doe light for a few seconds, well after that i noticed that dash lights were not as bright as they used to be, and they done adjust anymore either. so i get to work and then my dome light doesnt turn on with the door anymore.

Anybody else ever see anything like this? Just a dimmer switch or what?

 

[MustangP51]

I haven't worked on a 4th gen Explorer, so I cant help you much, but I would start by checking the dimmer switch. Find the wire that comes out of the dimmer and goes to the dash lights, hook up a multimeter and check the voltage. When you move the dimmer the voltage should change. If not then it is most likely the dimmer.

 

[Henders]

Dimmer switch problem.

Try adjusting the dimmer switch to the middle of travel to see if your dome lights come on (when you open the door). All the way in one direction turns the dome lights off completely. The dimmer adjusts the intensity of the dash lights along with the control panel lights for the AC.

 

[aaronajb1981]

So here is what was weird. I used the dimmer to turn on the dome light. After that the dimmer would not dim the lights, they just stayed at one level but they would still turn back on the dome light. So after work i decide to try to roll the switch, now everything works back to normal.

 

[smm1099]

That happened with mine. So after I left it alone, the dimmer shorted out and made all my running lights not work, I blew 5 fuses in 5 minutes trying to figure out where the problem was. I have to find a switch now to replace it with. I'd get it looked at if you could.

 

[dothedeww]

That happened to my 06 XLT...

I just slapped the side of the dash and it started working again.....i now have to slap the dash to get some lights to come on as well as getting the dimmer switch to work....

ill get off my butt and fix it one day....lol

 

[matsavol]

Mine just started doing this yesterday... I tried to adjust the brightness and then it went all the way to dimmest and the dome light doesn't light up any more when opening the door.

This morning the dome light and dimmer worked briefly but stopped after trying to find a proper position for the brightness. Opening door no longer lights up dome light and the dash lights are at their dimmest setting.

I'm guessing it is the dimmer adjustment dial? Anybody replaced it yet and confirmed working?

Any guides how to remove the dash to get access to the switch?

 

[nleipziger]

If you rotate the dimmer switch all the way to the end, it clicks, and it disables the dome lights and leaves the dash lights dim. Checked and see if that's your problem.

 

[matsavol]

This just happened again when it was cold. (Should not have touched the dimmer dial!) After driving a while to get vehicle warm it started to work by itself.

I'll try to pull out the light switch/dimmer one day to see if I can spot anything wrong with it. I believe it is fully electronic dimmer control module and you really can't do anything to it other than replace it. I recall asking Ford dealer about the replacement: It was a special order part and slightly over $100.

EDIT: Just looked at the electrical wiring diagram and this actually is analog dial and two switches.

 

[matsavol]

I took mine off. It was easily removed from the dash: Just pull upwards from underneath the plastic panel where the light switch is attached and the panel comes off. No tools required. Removing the dimmer switch from dash panels requires prying three plastic clips, for which I used a small screwdriver.

The dimmer switch is also easy to open: The guts do slide out by praying open four retaining clips. Then the interior circuits is exposed.

I don't see anything obvious wrong. There are two resistors that measures about 50 ohms each. The color coding suggest they are 49.5 ohm resistors. The adjustment dial (potentiometer) measures 538 ohms across, and the resistance changes smoothly when the dial is rotated. If anyone knows what the resistance should be please let me know.

The potentiometer itself is some special kind because it makes the full adjustment from 0 to 538 ohms in less than 90 degrees turn. (The potentiometer does turn 270 degrees but the value does not change after the first 90 degrees.)

Also if anyone knows what is the part number of the dial/swicth. The sticker on mine is faded so that I can't read it any more.

EDIT: Seems like the dimmer switch part number is 6L2Z11691BAA. Cheapest I found at parts.com just under $74 including shipping.

EDIT2: Found out that 7L1Z11691BA used in Expedition and Escape etc. should fit as well. The good news is that its price is only $22 including shipping! I took the gamble and ordered this instead. I'll post back how it turns out.

 

[matsavol]

Issue is not the dimmer switch

I received the 7L1Z-11691-BA part today and indeed looks identical to the original part. The bad news is that it did not fix the problem... There is a difference that the new part is missing the two 49 ohm resistors in the dome light off selector. Because of this the new switch dimmer control does not work at all. (I believe the SJB senses the resistors and if it doesn't match what it is expecting, and enters to the default "fail-safe" mode.)

Going back to the original problem, I believe the issue is in the "smart junction box" where the wires from the dimmer switch goes. The higher the resistance on the dial, the brighter the instrument lights should be. (This is based on the schematics diagram. The potentiometer is adjustable pull-down resistor.) With my original dimmer control I need to set the brightness to all the way to the max to have instruments panel lights reasonably visible. I believe that on the "smart junction box" there is another fixed pull-up resistor which resistance had increased significantly. I need to look where to find this "smart junction box".

EDIT: Found the location of SJB and removal instructions:
http://www.explorerforum.com/forums/showpost.php?p=3171074&postcount=17

Seems like the whole dash needs to come out? This seems a bit too much work for me...

EDIT2: Experimented with my old dimmer switch by adding additional 220 ohm resistor in series with the potentiometer in attempt to make my dash lights brighter. This did not increase the brightness, but created a new problem if I turned the dial all the way to the left (turn off interior lights completely) the light control system reset to a "fail-safe" mode. I believe the SJB is expecting the dial resistance to be near 0 at this point, but sees my extra 220 ohm, and decides the dial is broken. Therefore I had to remove the extra resistor and return the switch back to original.

So at this point is seems that I need to leave the system as is and live with it.