Dome Light doesn't work with open door

[BobThib]

About 2 weeks ago the 15A dome light fuse on our '99 Carolla blew. The interior lights and radio didn't work. Replaced the fuse and now everything works EXCEPT the dome light and ignition key light when the door is open. The dome light works in the ON postion, but not in the DOOR position.

The door open switches work ok because if the key is in the ignition it buzzes, and the "open door" indicator on the dash works.

I have 12v on both sides of the plug going to the dome light. This is clearly not correct. One side should have 12v, but the other side should be at ground when the door is open.

There must be something that turns the dome light off slowly when the ignition starts and I suspect that's the problem. If anyone has a wiring diagram or any ideas why these two items are not working?

[fishexpo101]

Sounds like the dimmer switch, light switch (light control rheostat) got cooked when the fuse popped. The light "ring" on the ignition and the dome are controlled by that switch. Another possibility is the DRL relay - as they also run to that main relay.

DRL relay - that would be a toughie to diagnose, unless you have a spare DRL relay lying around. The light control is easier to check - three pins - pin 1 is hot (battery), pin 2 is ground. Stick a voltmeter between pin 1 and pin 3, and see if the voltage smoothly sweeps as you turn the light intensity "volume" knob.

Other than that - you'll have to run the wires back and check for breaks in the wiring, shorts to ground, etc. Something had to have caused that 15A fuse to pop the first time around. That is probably what is still giving you headaches now.