Dome lights not working properly when truck is off

Hey y'all,

I installed some LED's in my dome lights after replacing a burnt bulb and it is giving me some issues. I've done some troubleshooting so I think I know what the problem is, I just don't know how to solve it. Here's what I've figured out: There is nothing wrong with the bulb, it turns on just fine when the truck is on; there is nothing wrong with the door switches, again they work perfectly when the truck is on; so then I figured since my LED is flickering, I could use a resistor but even with a high resistance, nothing worked; finally I tested the voltage and I'm only getting 300 millivolts(0.3 volts) when the truck is off and then 12 when turned on. So I know my problem is the voltage and I think there is a relay somewhere, but I don't know where it is or how to bypass it. I only ever keep the light on door mode so I'm not worried about leaving it on and killing my battery.

It just sucks because I have looked all over YouTube and TacomaWorld and haven't found a single person with the same problem as me. Hopefully someone can help.

 

No relay. It is all controlled by the body ECU.
In the ON position, it receives ground at a mounting screw on the light.
In the DOOR position, it gets ground by the the Body ECU.
Power is ALWAYS supplied by the Body ECU.

How exactly are you checking the voltage?
As in where are you placing the test leads on the meter to check?

 

I tested voltage on the contacts in the dome light. It read almost nothing when truck is off and then full voltage as soon as it's turned on. This is the same with my outlets as well. They don't work until the truck is turned on.

 

The 1st gen body ECU doesn't play well with some LEDs.
Some people have even damaged it using them.

https://www.tacomaworld.com/threads/dome-light-issues-04-prerunner.823116/

 

Ok so I've just been working on it today. I tried to look through the ECU but couldn't find the wire. Instead, I jerry rigged the ground wire into the bulb and the live end straight into my other hot wires for my offroad lights. It worked perfectly. For about a minute. It worked in both DOOR and ON mode and turned off when the door shut. But then after a bit, it stopped working, then randomly started working again. But after it started again, my door unlock button wouldn't work. (I never really use the unlock button so I thought it was fine but then I jokingly said, "watch, in a few minutes the door unlock will work again but the lights won't" and that's exactly what happened. Now it just stays on and doesn't turn off when the door closes.

 

Have a look at the thread I posted above.