PART2 :
During a recent pick and pull trip, I happened across a 93 4runner. Amazed to even find a Toyota at all, I jumped in and started looking around even though it’s a second gen. “There has got to be something in here I can use” I thought. This model had a sunroof in it, which had already been pillaged, but looking around the giant hole I found the dome light. It was in great shape and was even gray, so it would match my interior. And from the outside it looked almost exactly like my current dome light in the front of my truck.
I immediately thought that this would be a great addition to the back of the truck. My plan was to mount it directly below the factory rear windshield wiper motor cover in my truck so it would illuminate the entire tailgate area. So, I snagged it, muttering “up-grade”.
I also scored a sweet rear view mirror/ map light / door light combo setup out of the same truck. It too was gray, But that belongs in Part 3, which I will get to later. Back to the dome light project.
So I got the dome light home and the rear wiper motor cover off. Looking at the two, I knew I could get the dome light to fit on the small horizontal section of the cover on the driver side. It was going to be tight, but I was going for it. This would position the light almost in the middle of the truck, right over the tailgate area. So I figured light dispersion would be optimal.
The only issue I had was the way the dome light originally mounted in the 93 4runner. If I just bolted it up the way it was, it would have a large almost .25” gap between the base of the light fixture and the wiper motor cover. Being a perfectionist, this was not going to do for me. So I threw it on the mill and milled off the “extraneous” plastic material so I could get the mounting holes flush. It also significantly reduced the size of the hole I had to cut in the cover to get it to fit. Keep in mind this part is nonessential for it to work, but makes it look a whole lot more professional in my opinion. (Note: I later found out that older style dome lights, like the ones originally equipped in my truck would require much less if any milling to get them to mount flush.)
So, modified dome light in hand, I sized up the hole on the wiper motor cover using a template I made from a simple sheet of paper. I cut the hole in the cover using a razor blade. I chose not to use a reciprocating saw, or cut off wheel or anything like that because I was afraid that the extra heat would melt / distort the plastic and make it look like shizzz. It took a while, but the razor blade worked fine. In addition to milling the bottom of the light, I also had to radius one of the corners of the dome light with a file (only on the bottom side) to fit the curve of the wiper motor cover. It was not much and is not even visible when mounted.
Below are pics of the light mounted to the cover. Looks factory right?…cause it is.
So next was wiring. After staring at the switch and how it worked for a second, I determined that the two wire connector fed the unit constant 12 volts on the straight pin, and the curved pin was used in “door” mode to finish grounding the circuit when the door is opened. When in “ON” mode, the unit was grounded through a bolt hole to complete the circuit. Since my junk was mounted to plastic, instead of a metal substructure, I would need to run a ground wire. No big deal, just used the wiper motor chassis to ground too since there was already a ground wire running up the side of the fiberglass top to it. Also, I added a trick spade connector / ring terminal connector to make it removable because the wiper cover is removable….look at me thinking ahead right? For 12 volts I tapped into the “Dome” circuit like the other light, running a wire all the way up to the fuse box in the kick panel. I pulled the fuse panel completely out and removed the harness from the back. From there I was able to remove the fuse receptacle from the back and solder on my power wire to the existing dome circuit. See the next post (#4) for more detail on this step.
Here is the really trick part. Naturally, when in “door” mode I wanted the light to come on when I opened the tailgate, like you would expect, and go off when you shut it. Well, originally I thought I would simply snag another post style door switch like the front doors use and mount it, cause it would be just as factory fresh. Well, after looking around on the tailgate, I determined that there really wasn’t a good place to drill a hole, let alone be close enough to make contact with the actual door sheet metal when closed. So I scratched my head for a second and then realized that the logic I am looking for is already built into this truck! There is a switch in the actual tailgate latch that is used to control the rear window relay module and the “Back Door” dummy light on the dash.
Basically, for those who do not know, the window relay module will not power the switch for the rear window motor unless the back tailgate is closed, locked, and the top is on. It uses ground switches to determine all of these things. And if the tailgate is not fully closed and locked, the dummy light on the dash illuminates.
After some quick continuity testing and wiring diagram-age, I got the light wired up using the existing logic in the door latch detection switch. In order to get the light to only come on with the door opens and closes, I had to add a diode. Otherwise, the voltage would have back-fed through the back door lock switch to ground, and the dome light would have stayed on until the back door was closed AND locked. Which was not cool.
With the diode in line between the two switches, now it functions as you would expect. Open door, light on. Close door, light off. Even if it stays unlocked. For more information about wiring in the diode to get the desired "door" effect see post 6 below.
Threw in another cool white LED for consistency….and BAM done.
