I have a 2007 TR4 Sport Ed, V6. When the switch for the interior light on the ceiling over the front seats is set to door, it turns on regardless of whether any of the 4 doors is open or closed. Similarly, when the switch for the luggage compartment light at the back of the cabin is set to door, the light turns on regardless of whether the lift gate is open or closed.

The courtesy lights in each of the four doors turns on when the door is open and turns off when the door is closed.

If I'm looking at the correct wiring diagram (and reading it correctly), each switch in a door is connected to the body ECU. When the door opens, the door switch pulls the line to ground.

The interior and luggage compartment lights are provided with power regardless of switch position on those lights. When the switches for those lights is set to door, the other line to the light is connected to the ILE 13 pin of the body ECU. I assume the ECU pulls this line to ground when a door is open, which turns the light on.

It looks like my issue is a bad ECU. It looks like the ECU pulls the line to interior and luggage compartment lines to ground all the time. I'm looking for input from someone with more experience than me as to whether this makes sense or if I'm overlooking something.

Thanks in advance.

it might be a bad door pin switch, you can take it apart and clean it out and see if any corrosion and such.

It does seem like your door switches are ok because the courtesy lights are functioning but it only takes 1 bad switch to control the interior lights. That includes the hatch which doesn't have any courtesy lights to check.

I wouldn't jump to an internal issue with a body control module without chasing some wires first. If the lights are really being controlled on the ground side (I hate it when electrical is run like that) then a slight abrasion anywhere on the wire could be shorting it to ground anywhere in the system.

Maybe my 2004 is different. Both of those switches in mine are 3-way: always off, always on and door. I have the 330 watt radio with the rear seat headphone option and controller, so that light over the front is larger to accommodate the infrared receiver, but the switches for both lights work the same.

Highly doubt is an ecu issue along with the wiring, feels more like a faulty switch or contact issue, keep in mind it does have 16 years of wear and tear.

My 03 did that after I switched to led interior lights, little wiggle of the switch and forgot about it.

Cabin and cargo area light up regardless of what door you open when both set to "door" also when unlocking. At least mine does.

Thank you for the comments, especially that it only takes one bad switch to cause a problem. I initially assumed each of the door switches were okay because they worked to control the corresponding light in the door. However, I had overlooked the switch for the hatch. After a little research, I realized that the switch for the hatch is within the latching mechanism, which is more difficult to get to than door switches in the door jambs. The switch in the hatch seemed like the problem, but since it's a lot more work to get to I thought I would check the the door switches first just in case.

When a door is open, I think the door switch connects the dome light and door light (via the ECU) to ground. Removing the bolt holding the door switch in and pulling the switch away from the body, removes the path to ground for the two lights. For all doors, removing the door switch caused the door light to go off, but the dome light remained on, with one exception. This seemed to confirm that three of the switches were good. The exception was the rear passenger door. I think it stayed on and then tuned off.

I repeated the process and confirmed that disconnecting the switch for the rear passenger door turned off the dome light. I thought I found the problem. I was deciding whether to pay $32 to get a new switch from Autozone today or order one from Rockauto for $15 and get it in a week, when I thought I would double check that the switch was bad.

I disconnected the switch for the rear passenger door. The dome light went off with a delay. Then I opened and closed each of the other three doors. Opening a door caused the light to go on. Closing the door caused the light to go off, but with a delay.

I'm now thinking all the switches are good and I simply didn't realize or forgot that there is a delay of about 15 seconds before the dome light goes off.

Yes there is a delay unless you click the lock doors button on the remote, then the dome lights go out, at least on my 2004

This is interesting to me as I read all the replies. I've been scouring the EWD for the dome light circuit for the last two weeks while chasing a fuse blowing issue. I did find the cause of the fuse blowing issue but seemed to have created "dome light on for ten min" issue when all doors are closed.

Since the rear hatch door latch has been mentioned, I did replace the latching mechanism last year when the OEM went south. I wonder if this replacement mechanism is the cause of my dome lights staying on for ten min after I close the last door, then go for a drive, or walk away from the vehicle without alarming (at my house for ex).

Some things for me to ponder. If you have any feedback on my issue, please post up here so that we can all learn and not muck up this thread.

Dome light staying on after doors are closed and door open indicator not on
The BCU does have a 15sec delay after the last door is shut.