Interior lighting fault

[K11TCH]

Hi guys I have the 97 explorer, and the interior lights remain on constant. I've read all the online threads but they all mention door ajar light on also, I don't have that, I get the chimes on all doors when open with key in ignition, it's just solely the interior lights. Is there any fuses or relays to check and where would I find them.
Thanks

 

[koda2000]

Maybe a dumb question, but did you try turning the dimmer thumb wheel down? If so, I'm suspecting a bad dimmer switch.

 

[J_C]

Yeah fuses blowing won't make a light stay on. Relays generally fail open so those are doubtful too. There might be some one in a million chance that some kind of short circuit in the GEM could cause a relay to stay on and there are ways to test that, but odds are it's either the position or a failure of the dimmer module as Koda mentioned.

 

[K11TCH]

Cheers guys, I've only had the motor since last week, the previous owner just said the interior lights won't go out so he took all the bulbs out, I've acquired some more so when I'm not working IL be out testing what's what.

 

[koda2000]

Cheers guys, I've only had the motor since last week, the previous owner just said the interior lights won't go out so he took all the bulbs out, I've acquired some more so when I'm not working IL be out testing what's what.

My money's on a bad dimmer switch. They can be taken apart, examined, rejuvenated and lubricated, or just replaced. If it's not a door switch (which apparently it is not, as the "Door Ajar" light isn't lit) the dimmer switch is about the only thing that can be supplying constant power to the dome lights.

 

[K11TCH]

My money's on a bad dimmer switch. They can be taken apart, examined, rejuvenated and lubricated, or just replaced. If it's not a door switch (which apparently it is not, as the "Door Ajar" light isn't lit) the dimmer switch is about the only thing that can be supplying constant power to the dome lights.

Update..... I put new bulbs in the rear domes and the rear load space light I can manually switch them on and off but still won't go out on there own. Front domes have no fitting inside them and dimmer switch only controls the dash and works fine on that.

 

[J_C]

The dimmer module has two separate subcircuits in it. One could work while the other has failed. You could unplug the dimmer module.

If lights don't go out, that's not the problem and you can pull out the interior lamp relay if you want to stop the battery drain and could use a multimeter to trace the circuit.

If lights do go out, time to R&R the dimmer module. Some people have luck taking it apart and cleaning the traces, clearing off old grease and putting a little fresh silicone (dielectric) grease down, and looking for faults. However that is more a fix for the dimming (dash, etc) circuit not the other one. Others just buy a new module, or if you're handy with electronics diagnosis then maybe reverse engineer and test discreet components in it, for example maybe a shorted transistor.

 

[koda2000]

The '97 dimmer switch will not turn off the dome lights if there is a door open/ajar. This function changed in later models, where the dome lights can be shut off even with a door open.

And yes, the dimmer switch has two circuits. One for dimming/brightening the dash lights and one for turning ON the dome lights with the door closed.