[Beyond]

Hey guys, newbie here! It's my first time doing any electric mod so I figured I'd ask before I burn down the car or something.

I'm putting in a 2nd dome light in the cargo area and was following the thread on the other forum (Dome Light Installation, Rear - Scionlife.com) , where I will be tapping the power from the OEM dome light wires.

My question: where should I connect the ground wire into? The thread says 1 end will be connected to the mounting bolt of the new dome light, ok, what about the other end?


Any help appreciated! I got everything cut out and tested already, just waiting for the wires to go in.

[gravebox]

1 ground is your main ground, the other is a switching ground connected to a circuit that senses when the doors open and close and when you use your keyless entry.

figure out which one is your constant power by using a test light or meter. once you've found that, figure out which of the 2 remaining wires is your switching wire, you can easily check this wiith a test light and have someone open and close the doors or simply sit in the car with all doors closed and unlock and lock the doors Via keyless entry *if you have it*. you'll notice that it will switch power each time the door opens and closes and when the doors are unlocked and locked. the last remaining wire shouldn't do anything at all.

[PCH]

Originally Posted by Beyond

My question: where should I connect the ground wire into? The thread says 1 end will be connected to the mounting bolt of the new dome light, ok, what about the other end?

The description in that thread is wrong. The dome light uses two grounds and one power. Power wire is always + at all time. One ground is through the screw that holds the dome light to the roof. The other ground is switched and only there when the doors open or unlock requested by the remote.
At the factoryl center light the power is blue/yellow and switched ground is red/yellow so you need to tap and extend those wires to the back and conect both of them to the added dome light the same way.

If you are not attaching the new dome light to the metal roof then you need to run another wire to the chassis from one of the dome light base screws. But if you only want the light to turn on with doors open (Doors and Off modes but no ON mode) you don't have to do that.

[Beyond]

Ok I think I got this figured out now...

Originally Posted by PCH

If you are not attaching the new dome light to the metal roof then you need to run another wire to the chassis from one of the dome light base screws. But if you only want the light to turn on with doors open (Doors and Off modes but no ON mode) you don't have to do that.

Yes that's what I'm doing. I already spliced the 'power' and the 'door' wire to the back unit already.

I will be running the 2nd ground wire from the base of the 1st dome light to the screw mount of the 2nd dome light. So now both dome lights are grounded.

* * *

New problem... I am trying to put the lights back now, but I couldn't find a way to tuck the wires under the headliner without getting in the way of the original dome light??? I can't put the original dome light back in! argggg

I'll keep wiggling for a bit and see if an "ah-ha" moment will come up..

[Beyond]

Ah-ha...

Yes I was fiddling with it last night and realized I spliced the wires to close to the connector and there wasn't enough leeway to tuck the blue splicer block thingys out of the dome light indentation.

So I took those out and respliced the wires 6" further back, seems to work now.

There is a slight gap because of the thick (14 guage) ground wire... I will see if I can get that tucked somehow.

Gonna finish up the light tonight! YES!

[Beyond]

Done! Also installed two 9-pack LEDs.



Contrary to the write up I followed (Dome Light Installation, Rear - Scionlife.com) , you can actually install the rear dome light all the way back until maybe 4" from the edge. I'd prefer moving my light back another 1", as right now with the light installed 14" from the edge, there is a small 3"-4" portion of the cargo area block off by the seat top and remained dark.

Still super happy about the outcome though, everything looks factory and works that way too.

[PCH]

Very nice!