Headlights will not shut off even when vehicle ignition is off

fredferrellJanuary 17, 2009

My headlights on my 2001 Ford Explorer are now continuously on while the switch is off and the ignition is off with the keys out. The only way I can shut them off is by pulling the "Parklamps Relay and Main Light Switch" fuse. I unplugged both the main light switch and the automatic light sensor, but it didn't work when I put the fuse back in.

Any recommendations?


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I also wanted to mention that all the lights are on: the front, the back, and the parking (front and back). The fog lights are also on, but there is a separate switch that does turn these off, but all the other lights remain on.

    Bookmark   January 17, 2009 at 12:44PM
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The relay for the automatic light system is stuck on. It's supposed to turn the lights on when it gets dark out.

    Bookmark   January 17, 2009 at 4:14PM
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Were is the relay located? I checked the power distribution box and it isn't in there.

    Bookmark   January 17, 2009 at 5:12PM
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Do your headlamps stay on all the time, or do they time out after a couple of minutes after ignition turn-off.? If so, try this: Turn the lights off before shutting off the ignition.

If your lamps are staying on permanently after: 1) ignition shut-off, and then 2) light switch shut off, suspect something in the headlamp-off-delay feature. (This assumes that your vehicle is equipped with this feature.)

    Bookmark   January 18, 2009 at 1:05AM
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Just wanted to give an update on my troubleshooting. I put the fuse back in and all the exterior lights remain on. I pulled the relays in the power distribution box one by one to still see that the lights remained on. I have looked in a Haynes manual and can still not locate the relay module. The relay I am looking for is the one that controls both the park lamps and the headlight lamps. Does anyone have an idea of where it could be located?

    Bookmark   January 18, 2009 at 11:32AM
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So,why don't you phone the dealer and ask them ?

    Bookmark   January 19, 2009 at 10:59AM
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The headlight relay is inside the "Relay Module" behind the center of the dash.

    Bookmark   January 19, 2009 at 3:16PM
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Ok, here's an update on the troubleshooting:

I was able to locate the relay module and check all the relays. The park lights and the head lights run on seperate relays. When I pulled the relays, the lights would go out.

Next I thought that the Generic Electronic Module might be the issue. I unhooked all the connections to it and left the relays in the relay module and the lights are still on.

This is where I am at. I also pulled all the relays in the relay module except the park and headlights ones to see if the dimmer relay was the issue. I wasn't sure which relay it was so I pulled them all.

The way I see it I have eliminated the following possible points of failure: Main light switch, autolamp sensor, GEM, and dimmer relay.

Any suggestions?

    Bookmark   January 19, 2009 at 4:36PM
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Consider the likelyhood that BOTH relays have failed at exactly the same time.

Now go and find out what turns them on and how.

    Bookmark   January 19, 2009 at 4:52PM
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I have switched out the relays with others that have the same part numbers on them with no luck at it turning off the lights. I also just ran a continuity test between the terminal #2 on the headlight relay (where the power comes from when the relay is energized) and a ground. Since there is continuity, I am guessing I have a short and need to replace some wiring. On the back of the relay module, does it have connectors that plug into it? I am hoping I can get a section of the wiring harness to replace instead of having to run an individual wire.

Please let me know your thoughts.

    Bookmark   January 19, 2009 at 7:01PM
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Hi again Fred.

First, do you have auto dimming headlights? If so, unplug the connector from the rear the rear view mirror and see if your lights go out.

Now that's the last "silver bullet" that can be thrown out. All too often I see people make light of what a tech has to do today to repair someones car. You don't have to read too many threads right here in this forum and you will see just how rare it is to get respect for what we do. We DON'T just swap parts as you did by playing musical relays in order to figure out a problem with someones car. You should have noticed though, that when you were plugging the relays in, they probably clicked because they are "being commanded on". This command could be a false one such as a grounded wire. We don't actually call that a short because shorts blow fuses, that's not happening here.

Looking at the schematic, and not knowing for sure which system you have (there are two designs, one with auto dimming, and one with just Daytime Running Lights) makes it impractical for me to type out each step to lead you to diagnose this thing. Seriously, it would take me about 1/2 an hour to diagnose it, and three hours to type it all out. Average pricing for a tech/shop to diagnose this issue around here would be in the $100 range.
Keep in mind things like "Flash to Pass" and the fact that the multifunction switch is a significant part of the circuit. Any aftermarket alarm systems, could also be in play. I'm not going to be able to go into great detail, make sure there are NO blown fuses in any of the vehicles fuse blocks. A blown fuse would of course be evidence of a short occurring somewhere, and this can result in a back feed which can command a relay on.

Later today I can look closer at what you have written here again. But if you don't have the skills to do the diagnostics on electronics at this level you should plan to have a tech repair this. JMHO.

    Bookmark   January 20, 2009 at 9:13AM
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