Dome light problem

Discussion in 'SN95 V6 Mustang Tech' started by 2001Pony, Jan 11, 2010.


  1. 2001Pony

    2001Pony New Member

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    Drivers side door closes all the way but the dome light doesn't shut off like it's supposed to.
    I'm used to older cars with a button that the door pushes when it closes to shut the light off but I can't find anything like that.
    Where should I be looking?:shrug:
    #1
  2. stangfanatic

    stangfanatic New Member

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    I may be mistaken, but I think the door ajar switch on the SN95 cars was in the bottom rear of the door jamb ( by the bottom of the rear of the door, but on the body)
    #2
  3. MustangLX-5.0

    MustangLX-5.0 Founding Member

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    You sure there is no button? I could've swore the 01's had one. If it is anything like my 96, there should be a button on the door itself a little more than half way up. It closes against a metal plate just below the upper door hinge assembly. The metal plate sometimes gets bent in to where the button can't be pushed on when the door closes.
    #3
  4. Low_Hp

    Low_Hp New Member

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    The 99 to 04 mustangs have two latches. (one for door and one for dome light) They are side by side, the dome one sticks. I had the same problem. Takes some WD-40 and spray in the door latch. Then open and close the door repeatedly. Do it for the other door too just in case. Some use silicone spray after using WD-40 but I havent had any problems without it. Hope it helps.:)
    #4
  5. wmburns

    wmburns SN Certified Technician

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    Door switch interfaces to GEM

    The 99-04 Mustangs use something called a Generic Electronic Module (GEM) to actually control the dome lights. Think of it like a smart relay that can make delay decisions and such.

    The GEM takes input from various sources and decides what to do. For that reason, there no longer has to be separation between warning circuits and Courtesy functions.

    There is only one door ajar switch for each door.

    Try this test. Leave the key in the car and open the door. Do you get a key minder alarm? If the key minder alarm goes off when the door is closed, then the door ajar switch is working.

    If the door ajar switch is working then the problem is either in the head light switch or the GEM itself.

    Start by ensuring that the head light switch is NOT turned fully counter-clockwise as this will cause the dome light to stay on all of the time.

    The GEM is a solid state device and rarely fails. The part is likelyt to be $$ so it makes sense to rule everthing out before replacing.

    Has any radio work been done? The GEM shares the same ground as the radio. If disconnected, the GEM will not work correctly.
    #5
  6. Pizzaman

    Pizzaman Member

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    Funny this topic is here, today i was driving down the road and i got the lighter beep from the dash and my dome light came on. Then it beeped again(dome light still on) and then dome light went off. It did this process several times before finally no more beeping but the dome light stayed on. I got to my destination and got out closed the doors went inside, after 10 minutes or so i forgot to check to see if the dome light had went off and it didnt. I pulled the bulb for now. I did have radio work done a year ago or so.

    The beep was the same as when your dummy lights come on such as the low fuel light. It is NOT the loud "you forgot your keys or lights" beep.

    Headlight switch is not on

    I do get the keyminder alarm upon opening the door after shutting the keyminder still beeps.

    I must be looking at a GEM problem you think?
    #6
  7. wmburns

    wmburns SN Certified Technician

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    Is the door ajar cluster warning light on (not sure if your MY has one)? Does this car have an aftermarket security system? Is the key minder alarm sounding all the time? Must be difficult to drive.

    If opening/closing the door doesn't change anything, look first at the door switch itself. It is located inside the door. The Left front door ajar switch runs to GEM pin#13. The wire color is YE/BK. Also try the WD40/silcone trick as the switch may be sticking.

    The GEM is a solid state device and it rarely fails. More often it turns out to be grounding or some other issue involving a radio install. Other causes such as rodent activity, water, bad grounds should be ruled out.

    Before I go into a long post regarding what to check, are you inclined to fix this yourself? Do you have a Volt Ohm Meter (VOM)? This will require performing some detailed tests and posting the results.

    An option is to replace the GEM. I have never actual bought one and I do not know how expensive they really are. Did I help someone with a turn signal problem. Turned out to be a bad electronic flasher module. I believe the part was $35.
    #7
  8. Pizzaman

    Pizzaman Member

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    The keyminder is not running all the time, in fact that wasnt what initially started this problem. The beep that happened during driving was the softer sound that happens when a cluster light comes on (such as the low fuel). I know there are other instances when this sound happens but i cant think of them right now. The keyminder ding is alot louder more annoying. I probably wont try this if it gets too deep. I will try the WD40 trick however I am not sure what i am looking for in the jam. I am kind of old school, I was looking for the button type from older cars. Do you know what i am looking for in the jam?
    #8
  9. wmburns

    wmburns SN Certified Technician

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    I went outside to look for the door switch on my 2000. Can't find it. The wiring diagram says it is in the door. I suspect that it is actually INSIDE the door attached to the latch.

    HOWEVER, since you stated that the keyminder shuts off when the door is closed, this confirms that the door switch is working.

    Since there is more odd symptoms than what would be expected for just a bad door switch and the switch is working, IMO, look for rodent activity, water, or a bad GEM.

    Good luck.
    #9
  10. Pizzaman

    Pizzaman Member

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    Will do and thanks for your posts and time. Have a great weekend.
    #10
  11. Gixxed

    Gixxed New Member

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    Thanks for this post...... Just had it happen to me....
    WD40 fixed it
    #11
  12. Aeroman

    Aeroman New Member

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    Pretty sure the switch is sensed at the latch. Older vehicles had seperate switches for the dome & door ajar, sounds like it is now integrated with the latch mechanism. Sounds like the this "GEM "so far. If you want to check the latch you'll need to take off the interior door trim & look at the latch from inside the door , there is an electrical plug attached to a switch which senses the latch claw position.
    So you don't have a door ajar warning light illuminated?
    #12
  13. Zac Heulings

    Zac Heulings New Member

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    What if the cip that holds the sensor is broken where can i buy a new clip? or do i have to buy the sensor to?
    #13

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