I have a 2005 Excursion V10 4WD Eddie Bauer edition. Within the past month I have noticed that the interior dome lights and running board lights don't always come on when I open the doors. The dimmer switch is set to the highest level without being turned on and all of the dashboard lights work. I turn the dimmer switch on and sometimes the interior lights work and sometimes they don't. The door switch seems to be in good shape as well. If I turn the dome lights on individually they work so I know that there is not a problem with the bulbs. Any suggestions as to where I can look for the problem? Thanks!

 

First off, welcome to the best Excursion forum!


Is it limited to one door only? Or does it happen when you open any door? When this happens, does the door ajar light come on? If the door ajar light comes on but the dome lights don't then it may be a bad connection between the instrument cluster and wherever the wire goes to from there. If you're not getting a door ajar light either then it could be a bunch of things.


When the door jamb switch goes bad on the '02 (I'm not sure about the other years) the dome lights stay on. On the '02 model an open circuit turns the lights on. When the switch goes bad it gets stuck pressed in which opens the switch (sound backwards, I know, that's how ford designed it). If you have a short to ground somewhere in the circuit, even if the switch is opened, if the short is before the switch, the VSM will still think the door is closed.

Here's how to check the switch itself:

The switch is buried under the latch in each door. Take off the door panel. Take off the 4 screws next to the door latch. Then you can maneuver the latch out. You might need to pull off some of the rods that connect the latch to the door handles first. Just unclip them carefully so the plastic clips don't break. When you get the latch out, the switch is on the bottom. Use a flathead screwdriver to lift the black plastic up so you can turn the switch and pull it out. There's a little etching on the black plastic next to the switch that says "lift here".

Once you get the switch out, it's easy to tell if it's bad. It's supposed to spring back up when you push it down. If it doesn't come back up, that's the bad switch.

I'm not sure if Ford kept the same design with the VSM through '05. If they did, this is probably the easiest way to find the short:

The VSM is located on the firewall behind the radio. if you lay down on your back from the drivers side footwell and look up behind the radio you can see it. It has 3 plugs, one of these is the door switch circuit. I can't remember which though. Here is the pin layout, ground is on pin 14 and the door switches are on pins 4, 5, 6, 11 and 12. Check for continuity on each one while all of the doors are OPEN. If the doors are closed you should get continuity between each pin and ground. If the doors are open you should not get continuity. If you get continuity on one, that's your short. Run a new wire to that door or try to find the short. Common areas are by the door sills. Pull them up and check each wire.

Good luck troubleshooting and let us know what you find!

 

Thanks for the tips DidieX. I just went out and checked every door and both rear doors and hatch door when opened caused the dome lights to come on, no problem. When I opened both front doors the lights would not come on. So I walked around and opened each door again. Both rear doors and the hatch worked again and this time both front doors caused the dome lights to come on! Now I'm really stumped!
P.S. The door ajar lights did work for all 5 doors.

 

Interesting. Did you notice if the door ajar light was on when the front doors were open but the dome light was off? I think the door ajar light only functions when the ignition is on, so be sure to check everything with the key in the on position.

If the door ajar light is on but the dome lights don't come on, it's likely somewhere in the dome light circuit or a bad instrument cluster (there's relays in there).

If the door ajar light is also off when the dome lights are off then it is either a problem with the door jamb switch circuit, the VSM/GEM or a communication issue between the VSM/GEM and the instrument cluster (this was the issue with my 2002 Ex).