please help with light problem

So, my 2003 Tacoma's curtesy lights and dome lights will not come on unless the truck is running, I have checked all fuses that I can think of the blubs are good but replaced for good measure.
I also check the door jamb switches for continuity, and they are both working well. when I check the dome light to make sure it is getting voltage with the truck off, and the dome light switch set to the on position I get 3 to 4 volts with the truck off but with the truck is running, I get 12 volts. When I check the door switches and the power going to them it is also only 4 to 5 volts. so, I'm assuming that it is supposed to be 12 volts there also instead of 4 to 5 volts. but I am at a loss for what to check next I can't find a diagram or anything. any and all help is appreciated guy and girls' thanks in advance.

 

Are you using a LED bulb?

 

yes, but had the problem before that too with normal bulbs.

 

When the dome light switch is on the circuit grounds through the screw on the light . When switched to Door it grounds through the Door switches being closed. (Door Open)

With the engine running you should have with all the loads on Lights ,blower motor on high Radio on 13.5 VDC or more.

Engine off you should have 12.5 VDC.

Check your voltage from the battery to the fuse block Dome fuse see what you have should be 12.5VDC

Battery terminals clean and tight ?

Negative cable to the inner fender making good contact .

Some place you have a major voltage drop

Any aftermarket electrical loads or wiring?

Good luck.

 

what fuse is the dome light fuse in that block? and i have not aftermarket anything on this truck electrical wise.

 

How did you check the fuse and not know which one it is?

You beat me!

 

The body ECU controls the dome lights.
The door switches are just ground signals to the body ECU.

 

that's what I'm hearing I'm also hearing I need to have the dealer put a new one in to be programed. I checked the voltage coming from pins4,10 and 11 which i was told are the ones that feed the door switches power and when i did pin 4 and 10 had 5.8 volts and pin 11 had no voltage.

 

How were you checking the pins?
With the connector unplugged from the ECM?
Or were you back probing the connector with it plugged into the ECM?
5v might actually be correct. I still haven’t found the information as to the switch voltages.

I’d be more focused on the actual voltage to the light than the door switches.

 

I was checking the pin voltage from the back while plugged into the ECM with the truck off and pin 11 had no voltage and the Toyota tech I reached out to said that all 3 of those pins should have 12 volts to them and if they didn't the ECM is faulty.

where else would you suggest look for the voltage loss at the light though?
not sure if I mentioned the dome light and the courtesy lights both don't turn on when I open the door with the switch on door and when I checked the dome light voltage with the truck off it only had 5 volts.
when I start the truck with the door and switch still set to the same the position the dome light jumps up to 12.5 volts. turn truck off drops back down to 5 volts.

here is the diagram the Toyota tech sent me by the way if anyone else wants to check there truck and see if the voltage on the pins 4,10 and 11 is 12volts for sure.

 

While I’m not positive, I do think that the voltage on pin #11 will be 0v with the door open.
I bet if you were to close the door, the voltage will match pins #10 & #4
Or open the other doors and they will match #11 at 0v

 

that is correct I just tried it and in the weird contortionist position I had to get in will all doors closed pin 11 had 5.7 volts pin 4 and 10 had 5.5 volts. I opened both doors and it all went to 0 volts except pin 10 it had 3.5 volts with both doors open.

 

so, I feel dumb but the old non led bulb I had was bad I put a new none led in, and the dome light works when I open the door not the courtesy lights though. so guys how do I make the dome light work with the led?

 

LED's are light emitting diodes, electricity only passes through them one way, did you try flipping the LED the other way in the socket?

 

Yes I did no luck though I did hear from someone that the first gens have problems with some led and that you need some with resistors canbus led lights so I am going to try those next

 

Did you ever figure this out? I have the same issue. Courtesy/Dome lights only come on with engine running. If it were an LED problem, they wouldn't work at all.