Extra Dome Light Issues?
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=84198
Printed Date: May 09, 2025 at 1:59 PM
Topic: Extra Dome Light Issues?
Posted By: italian_virus
Subject: Extra Dome Light Issues?
Date Posted: October 16, 2006 at 11:14 AM
Hello all, I have an inquiry regarding an extra dome light in my 1995 Honda Civic. When i had my roof off i decided to make an extra dome light. All i did was spliced(did not cut) into the existing dome light wire run another wire in between both head visor's, now before i put the roof back up i measured the voltage between the existing dome light connection, and the new wire that was run.. The value came out to the same, no changes. I put the roof back on, measured the voltage again, same voltage across both wires(These values are going with the car on, and the car off). I connected the extra dome light wiring tried the new light.. nothing... The existing dome light is working correctly but the other one does not work.. Now i am aware that you cannot have to much of a load on an existing wire, but its a dome light whats the most voltage it could take????, I tried changing the fuse rating see if that would do anything.. that did nothing as well. BUT when i went to measure the voltage across the existing dome light the voltage was higher, and i was experiencing a voltage drop across the new wire that was installed.. If anyone has any idea on maybe what i am doing wrong.. something i am missing? any help would be greatly appreciated... Thanks
Replies:
Posted By: bsd1
Date Posted: October 17, 2006 at 3:01 AM
Why don't you just use the foglight wiring similar approach: Use the (+)parking light to 85 to energize the relay and get a constant 12v to 87.
But replace (+)parking light wire with your (+)domelight wire. This way it won't even overload your domelight, you don't even have to upgrade your fuse rating, the domelights won't be dimmer than normal.
Posted By: Chris Luongo
Date Posted: October 17, 2006 at 6:13 AM
What did you use for the second domelight, something out of a junk car? Another Honda or something else? How many wires does the new domelight have, two or three?
Here is how the domelight system on most cars, including yours, works:
There should be two wires coming up one of the roof pillars.........probably up the driver's side A-pillar.
One wire carries positive, constant power at all times.
The other wire makes a ground only when the door is open. (usually GREEN/ red on Hondas).
Thirdly, the domelight itself has to be connected directly to groud, so that you can turn it on using the overhead switch........it might get the ground simply through its mounting screws, or there might be a third wire that is connected to body metal up inside the roof somewhere.
(Note: if the domelight were not grounded, it would still work when you open the door---only the manual switch would not work.)
So, maybe some of that would point you in the right direction to troubleshoot this yourself:
--Your new domelight needs constant power on one wire, and ground-when-door-is-open on the other.
--If your new domelight has its own on/off switch, and you want to be able to use it, the light must have its own ground.....but if the switch isn't important, the ground is not necessary.
--If your new domelight IS grounded, the two other wires ARE polarity-sensitive. If you connect them to the Honda's wiring backwards, the Honda's fuse will blow when you open the door. No big deal, but something you should know.
(If the second domelight is NOT grounded, however, polarity wouldn't matter at all.)
Posted By: italian_virus
Date Posted: October 24, 2006 at 11:38 AM
Well the dome light is from another honda, Exactly the same as the one i currently have in the car. I think you just made me realize something, if your telling me that the stock dome light gets its ground from the two mounting nuts, i have no grounded the new lights, because there is no threads to mount it. But the problem is that the new light does not even turn on with the door open/closed, while the original one works..
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