Electrical Map Light / Snake Light

whitefoxgt

Member
Feb 18, 2004
12
2
13
1990 GT Hatchback. Snake light only works when doors are open or I turn the dimmer switch on all the way which brings on all the interior lights. All the wires look stock and haven’t been touched. Any ideas?

Thank you,
 
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Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
38,607
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Massachusetts
Is your glove box light functional and does it have all the wires? There should be two Light Green/Yellow wires into the glove box light. One is the feed from fuse #8, and the other goes up to the map and vanity lights to feed them.

Tapped into this wire is the right courtesy light switch, which feeds the left switch and then to the dimmer.

My guess is you lost power from/to the glovebox light somehow and you are not feeding the map light normally and only when the dimmer switch is activated. I would test for power at the glovebox light and then from the LG/Y wire on the glovebox light up to the map light to see if you have continuty and constant power there.
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
38,607
14,533
224
Massachusetts
Here are the diagrams. The confusing part is they show the convertible, sunroof and “no sunroof” cars on the same page. The middle pair of wires apply to cars with the map light.

64004110-D261-45E6-9904-D15A77E27F4A.jpeg


ABEC2972-E0CC-4C7B-BBE6-59FA63A931CF.jpeg
 
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whitefoxgt

Member
Feb 18, 2004
12
2
13
Is your glove box light functional and does it have all the wires? There should be two Light Green/Yellow wires into the glove box light. One is the feed from fuse #8, and the other goes up to the map and vanity lights to feed them.

Tapped into this wire is the right courtesy light switch, which feeds the left switch and then to the dimmer.

My guess is you lost power from/to the glovebox light somehow and you are not feeding the map light normally and only when the dimmer switch is activated. I would test for power at the glovebox light and then from the LG/Y wire on the glovebox light up to the map light to see if you have continuty and constant power there.
This makes a lot of sense. I know that the door jamb switch on the passenger side has failed. When the Passenger door is open none of the courtesy lights come on. Only when the drivers door is open will the lights come on. I will start in the glove box and work my way around. Thank you for the info, this was very helpful.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
Try spraying the switch on the door jam with wd40 and pushing, I believe it's just a grounding switch and the spring gets gunked up and sticks, they rarely fail.
 
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