So, I feel like an idiot. I also feel like I’ve done this before. I mean writing this, so forgive me if this is a duplicate post, but when I tried to point it out to someone I couldn’t find it. I had a perfectly working dome light and I made it slightly worse, and slightly better. To remove this light there is a plastic cover that is very fragile. mine was perfectly intact and I got it off and on several times… before breaking it in half. I would have had it done too, had I not made the lower bone-headed moves. Once that cover is off you can remove the two screws from the roof, remove the spade terminals on the back, and finally un-clip the plastic from the metal.
I recommend these solder joints
Here is the inside of my dome light. You can see the discolored plastic where the bulb heat has done some damage over time. You can also see how I have added LED bulbs here. I also added some solder to the riveted joints to prevent them from being high resistance joints in the circuit. The side bulbs have the correct polarity, but the middle one you have to try both ways before you know you’ve got it right. That LED I needed to modify because it came without those two metal ends. The light bulb this emulates has two loops out the glass and I stole the caps from my old bulb. That connection plus the fact the loops on mine were steel and not copper made for a terrible connection to power and a very intermittent light.
so much tree spooge
Grungy but it works, I added tons of solder to firm up the connections on these joints (and got a little silicosis from grinding down the PCB to fit inside the covers). That works, reliably, every time.
I was going to replace the switches because they felt sloppy (felt like the metal cage over the slider was coming off) but I found they’re actually fine and after cleaning them they went back together smoothly and operated that way as well.
beware stress hardening the metal
Ok, on to the part that makes me an idiot. Start with the questions I didn’t ask: What lights are in the dome light? when can they be on? when are they commanded to be on? how many wires does that take? how could they do it with fewer wires? The Map lights can be on at any time, the dome light is on when switched on from the switch to the left of the steering wheel or when the door is opened. This means that the dome light is switched from the dash board area and the map lights are switched at the light. The map lights need an always on power source and ground and the dome light needs to be switchable. Rather than sending 12v and switched 12v with a common chassis return they sent a 12v and switched ground while also using a chassis return. I was not expecting that. I was not expecting that so much that I instinctively jumpered what looked like two ground connections and when it was all installed it acted like a door was open.
My shame (do NOT do this) from top to bottom is 12v (spade), switched ground (spade), chassis ground (screw)
I was so used to switched power and constant grounds that when I tried to test this on a bench I found that the map lights didn’t work. I was applying power to the two spade terminals and got no map lights. When I discovered my error I did not realize that it worked before I took it apart and would probably work once installed. I determined that I would improve it by jumpering the grounds together, and it all worked great. Until I put it in the car. Once I connected the grounds together this made it seem like the door was open all the time, providing a path to ground that an open door was supposed to.
By the time I realized my error and corrected it I had broken the dome light cover. I decided to buy and modify a Ford one because I had heard it was possible. I determined that it needed to be bent slightly around the metal case. I fucked this up too.
extra shame
the plastic bubbled under the heat gun and almost didn’t move at all anyway. I used to be good at this, I swear (this is where I insert the middle school plastic heat bent project that also had bubbles showing I was never good at this).
That’s it. I taped back together my broken cover, stuck it in, and am done. now I have a melted aftermarket ford part, a cracked OEM AMC part, and some LEDs to replace bulbs that weren’t burnt out. Is this a win? The home page for this project is here, it has a link to the album of pictures.
Evan's Techie-Blog 