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Old 09-06-2009, 06:27 AM   #1
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Default Dome Lights

So I see it's a common problem for the dome lights to not work, thought I'd do a quick write up for how to check what's wrong with them. From my experience, it's always a bad ground...

As with all light circuits, check the simple stuff first. In this case, that would be things like a fuse or the bulbs themselves.

Dome lights are on 2 different circuits; one to turn them on when the door opens, the other when you press the button for the individual lights. Both circuits are powered by the same "+" source (red wire that plugs into the back of the assembly). This is usually not the issue (as long as you don't have any broken wire or anything). The + wire will run directly to the bulbs, as it does not switch on or off. You can check to see if it's good by using a multimeter to check continuity between the + pin the electrical connector plugs into, and the + contact on each bulb (the one that is centered on the butt of the bulb). If you have continuity, the + is good.

The automatic door light circuit is grounded by the black wire from the electrical plug. Through a combination of rivets and short lengths of wire, the ground runs through the rocker switch (to turn them on with the doors or to stay off) to the casing of each bulb. Once again, you can check to see if you're connection is good by checking continuity between the "-" pin the connector plugs into and the bulb housing (little part that the bulb sits in). Make sure the switch is in the "on when door's open" position, otherwise you will not have continuity.

The push button light circuit grounds through the dome light assembly mounting screws. Each light has it's own grounding screw, but both grounds are also connected with a wire so that if one is bad, they should both still work. Around the mounting hole of the plastic housing is a metal ring that is connected to the ground wires for the bulbs. It is very common for this ring to build up corrosion, thus breaking the ground connection. Give these a good cleaning, and verify you have continuity between the ring's and the bulb holders. Please note that you need to have the push button switches in the "on" position when you do this test.

If the continuity is good at all points, reassemble the dome light assembly. Make sure the 2 mounting screws that act as the grounds are free of dirt or other contaminants, as this can result in a poor connection. If after reassembly the lights still don't work, the problem is likely before the lights themselves and would require more in-depth troubleshooting.
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Old 09-08-2009, 01:02 AM   #2
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hey guys...im havin the same prob aswell, as u said alot of us hav this prob lol
...anywayz i think my problem is my passenger door switch (cant think of the name of it atm haha) cause its broken it stops the circuit from being completed when you close the door, or the other circuit when the door is open.
that could b another problem if some1 is havin those troubles, it would hav taking me a while 2 figure that out if it wasnt for my friend "helping me", by pushing it until the arm in it flung out hahaha, then we noticed that the metal tab inside was broken (so odviously there was no connection)
im goin to attempt to repair the switch till i find a new 1, and i bought a universal one that is completely different, but it mite have to do if worst comes to worst hahaha
so if your grounding in the dome light assembly is good, then you might be in the same boat as me
...so i will keep you posted on the outcome

also...if i cant find these door switchs (cause the mk3 is so bloody rare round here lol) would any1 know if there is another car with similar switches?...or a certain brand that makes a similar aftermarket 1???
...much appreciated for any help
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Old 06-04-2010, 10:46 PM   #3
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Default Toyota supra dome light and horn repair

How do you get the dome light apart? I don't want to break it. Do you pry it off from the base or do the 2 light panels pop out to get to the screws?? No external screws so I would rather know what I am doing. I found a blown 15amp fuse in the fuse box for the dome. Also some idiot had put a big pin display badge you know the kind you pin top your shirt during an election, up into the headliner right in front of the dome light. I had a tough time pulling it out. I suppose this might have shorted them?

I also have no horn though I have checked the fuses and it worked fine when I first started bringing this red Supra back to life?

The Horns are at the front of the car, yet they seem to have two connectors coming off of them but I can't tell how they are hooked up? I looked at my black Supra and it is the same. These connectors have nothing attached to them. My fuse is fine for the horn the steering wheel pad seems to click OK when I push for the horn. I would rather not attach an accessory horn button into the dash.

I can hear the relay behind the kick panel clicking when I try the horn. Does this mean the relay is bad? Or does this mean that the relay is working? Duh!

I am not very good with electrical. My Chiltons manual doesn't even cover the dome light or horn that I can see.
Any thoughts would be greatly appreciated


I went a did some searching and I read that the dome cover just pops off. Mine however does not I have pulled and pulled just short of braking it and it will not release. HELP! HAHA how do you get this damn thing off? Has mine been glued????

I did get the fog lights put in. Turned out I had purchased them from ebay sometime over the past 7 years. Here are pics of the install.


OK I continued on reading other forums and found some info and things to try for the horn
Removed the passenger side horn hooked it directly to the battery and got nothing out of it. Went up to my black Supra took offthat horn tried the same thing nothing happened. The wireing to the black Supra horns ismissing or busted off.

Didn't have a voltage checker so I went to my boxes and found a Honda Shadow motorcycle turning signal.

I took my jack handle and wedged in-between my drivers seat and my steering wheel horn pad (button)

I attached some speaker wire to the ground post of the battery negative terminal and touched the other lead from the turn signal to the horn terminal positive wire.... and I got light! So I know I am getting power from the horn so I figure my horns are bad. There is a boxed contact on the horn and then there is a rubber sheathed something coming off the horn. What is that rubber sheathed thing? I have attached pics. I am wondering how the horn gets its ground because the arm it mounts onto is painted and does not appear to have ever given a ground to this horn.

I got the cover off finally.

Could you further explain to me the soldering one might do? My dome lights are not working. I pulled unit from my other car I hooked it up and it worked fine for about 5 minutes even the dimmer function then it just stopped. I have power to the unit but for the life of me can not figure what happened to make the second assembly fail after a few minutes.

My bulbs are good, my fuse is good, I tried running a new ground made no difference.

What terminals did you solder?

Any thoughts?


Well as luck has it I found a fix for the dome light before anyone could answer my questions. Here is how it went:

After reading how soldering was required and also reading somewhere else that someone inserted a screw somewhere, I took my battery charger, attached the negative to one connector terminal and then started there, Immediately I found the problem. One of the terminals on back of the unit was no longer connecting to the wire underneath! It looked perfectly normal but if I touched power to the center of the rivet it lit up, but if I touched the power to the tab that was connected to the rivet and has the tab that goes in the connector, no light!

So I new this was where the rivet was somehow not connecting. I was lucky in that it was the first contact point I checked. It might be the very weak spot on all these dome lights or you might have to test and search for yourself to see if you have a bad riveted connection on your light assembly. Remember they will appear to look perfectly connected and riveted!

I didn't feel like searching for solder and my soldering gun. I have not soldered anything in many years and as I recall I sucked at it. So I got my drill and a small drill bit and I drilled the solder out.

I then needed to be lucky enough to find a nice small tapered metal screw that I could use in place of the solder. My first thought was.... McDonalds Happy Meal toys! I had to look pretty good to find a small happy meal type toy that had a phillips head instead of the weird triangle screw head.

I found an Easter Toy that once topped a plastic container of candy. I pulled the bunnies screws and Whallah I had a screw that would work. I ran the screw through the open loops left by the rivet being drilled out.

I tested the light and it worked fine! I installed the light back in my Supra and so far so good. Of course I can solder it later if this does not hold but I took a pic for you guys because no one had actually shown what they did.

Check out the last pic to see the screw ran through the connector tab and into the eyelet on the other side that is attached to the positive input lead.

Almost ready for Inspection this was a big one just for my own enjoyment of the car. Can't live without an interior light when you have a 7 year old daughter. Will buy some cheap horns from Auto Zone tomorrow. Cost of repair????
One Dismembered Easter Bunny!

Thanks for reading this post.


My Horn works now, only bought one for now from auto zone for $16.00 thats all I need to pass inspection. Will get the other in a week or so.
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Old 04-03-2011, 01:05 PM   #4
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Great info guys. Thanks. I have been in the dark for too long.
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