Dome Light Only Works in ON position

I’m having some issues with my dome light that I can’t figure out. The dome light will only work when in the on position. I have voltage at the light when in the on position and I’ve cleaned the light contacts. I have also swapped it for a light fixture that I know works because it turns on in my other first gen. Any ideas on what to look for.

 

You are likely missing a ground.
In Door mode, when a door is opened, the Body ECU provides the ground.
I’d first make sure you get the same result by opening each door.
You might have a bad door switch. Or possibly 2 bad door switches. (But not likely).
Then you need to move on to the wiring to the ECU.

There should be 2 wires in the light.
Black - power
Black/White - Ground

The reason the light works in On, is because it uses a different ground. Which looks like the body.

 

You don't happen to have LEDs in it do you, that is a known issue when using LED bulbs.

 

Check the easy things first.

Also those switches get dirty at times and don`t close.

When the doors open the door switches close completing the circuit. check the door switches

when the switch is in the on position it grounds through the screw into the body

Per my 2000 EWD

 

Door switch -> ECU -> Ground
ECU controls all functions in Door mode.

 

If it doesn't work by opening either door, check up at the socket for 12V when door is open. The ground there is probably okay since you can light it with the switch.

As stated by @Bivouac above, at least some years (2001...?) these switches ground thought the bolt that holds them to the body. Try removing the bolt, clean, re-install. If it's a "piercing type" bolt, meaning no weld nut to screw into, tap the hole in the body closed with a small hammer before re-installing the bolt. That way it will get a tighter connection to the metal.

2000 wire diagram: note ground at the door switches (at bottom of pic)

 

Just what year is this from??

We still call it the integration relay not the Body ECU

 

They seem to just be sheet metal screws but with a 20 plus year old truck .
Who knows how often it was changed.

 

2001 FSM

 

PM inbound

 

Thank you Thank You!!

I am very happy with what you sent

Goes to show how one year difference can change so completely .

Can I send you any I would be glad to please let me know.

 

Nope. Your willingness to help others on the forum is payment enough.

 

Your more then Welcome!

 

I have checked both door switches and still nothing not sure what I’m looking for at the ecu

 

looking at TNshooter`s schematic !!

Do you get into much electrical trouble shooting ??

At this point I would run a jumper to test things I have many fused jumper wires of different lengths

Dome switch in door from where the black /white wire attaches ( dome light) to the green wire at your left door switch. Just how did you test the door switches?

If your bulb lights you have an open circuit between those two points. Now the hard work starts.

Good luck.

 

OP still hasn't answered if he's using LEDs, it's a known issue with LED bulbs in some 1st gen trucks.

https://www.tacomaworld.com/threads...s-only-work-when-the-key-is-turned-on.760294/

 

Yes indeed I noted your 1st post .

One can only do so much .

I use LED lights I have no use at all for bulbs. Never had a problem but hyper flash a easy fix.

 

Yea I have LEDs in my dome on my 2nd gen as well, I'm just trying to eliminate that variable as some LED's don't play well with electronic systems.

 

If i can butt in here? Im having a led/dome/map light issue... ive had leds in them for a few months now and everything worked fine. Tonight i switched them out for a brighter dome and dimmer map lights(one is red, works awesome at night)...when i first put the replacements in tonight everything worked as before..even used the same brand...but when i got home the dome did not come on when i opened the door..i got out shut the door and seconds later it turned on for a sec and shut off..wtf? So i hopped in and cycled the switch back and forth and nothing. So i hit the map lights and nothing... so i stuck the key in the ignition and turned on with engine off...they all work, including the dome with the door...any ideas? Gonna eat and go back out at -30f and mess with it lol..

 

Put it back to the way it was when it was working, if it works right again then it just doesn't like those LED's.