HowToRepairGuide.com: Interior dome light and cargo light will not shut off?

In this case my customer noticed problem on his ford Explorer sport model of year 2002.

In his case,the dome light and cargo lights were not shutting off.

On that basis the troubleshooting is as follows :----
Have you disconnected the battery for 5 min and then put it back and see if the system resets itself, sometimes this works , its like a reboot for the truck ,,, remove the negative battery cable from the battery for 5 min and then put it back on ,,and see if the problems goes away .

IF NOT........ then read further

If you start the truck up and have all the doors closed and look on the instrument cluster and there is a warning lamp on for door ajar ,, then one of the doors has a bad door ajar switch in it.

BUT if there is no warning lamp on ,,then you may have turned the dome lamp switch on , on the dash mmm the same switch that adjusts the dash lamp brightness also turns on the dome lamp if the switch is turn up all the way ,, so make sure the dimmer switch is not turned up all the way causing the dome lamp to stay on.

BUT if there is no door ajar lamp on with the car started , and the dimmer switch is not on all the way , then do you have any add on alarm systems,, most add on alarm systems tie into the dome lamp system , and this could be causing the dome lamp to stay on.

Well if you have keyless entry on this truck , then there is a module located behind the passenger side seat , behind the rear interior panel called the central security module, and it could have an internal problem , but this car is known for the dome lamps to stay on , but there will also be a door ajar lamp on at the same time.

If it is the central security module,then its about $250 for the part and $250 to install,, if you decide to disconnect it , you will loose power door lock , dome lamps, alarm system , remotes wont work.

But if this is not helping then inspect the fuse and relays controlling the system.

The details are as follows :----

There is not one fuse you can remove , that will just kill the dome lamps and not kill other stuff too.So you will have to go after the relay , there is an interior lamp relay located under the drivers side of the dash , toward the center of the dash , above the gas pedal , there you will find a black box with a cover over it , if its never been opened before then it should have some tape on it you have to brake to open this relay box , once you get the cover off, the relay box holds two big relays on top , and four little relays on the bottom ,, the little relays at the bottom of the relay box are the ones you are after ,, the left bottom one is for the dome lamps ,, remove this relay and switch it out with any little relay that is right off it .Then test the dome lamps,if they work ok , then you know the relay was bad and sticking and you can get a new one ,,, if it still acts up you can just remove the relay and this will only kill the dome lamps.

To open the relay box,

there is a tab on either end to release, on the cover, pull on a tab to pop the cover off.

Now if after removing the relay the dome lamp does not shut off,then its not relay issue.

This is how the system works, a door is opened or the dimmer switch is turned on .Then it sends a signal to the GEM, generic electronic module.This module is located in the dash behind the radio.Then the GEM grounds that dome lamp relay which sends power to the dome lamps and turns them on ,,, so you stated there is no door ajar lamp on , and that the dimmer switch is not on , and there is no add on system in the truck , so you may have a bad GEM, but thats a very expensive, and not a common problem ,, so instead of directly replacing this costly GEM module its advisable to get this tested by ford tool.Without using a ford computer to talk to the GEM ,its not possible to see whats keeping dome light on.

This details will help.

Thanks.

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