Hi all, I am new here,

I have a 1999 Toyota Camry with 190k miles on it. Recently my dome light went out so I have decided to replace it with an LED equvalent. Problem turned out to be when I tried to replace the bulb, the 7,5 dome fuse (under the hood) was blown. I though no big deal so I bought more fuses. I kept blowing the 7.5 fuses so I tried a higher ones. Well call me dumb if you wish (im a newb to cars, but I am trying to learn) I ended up with a 30A fuse in place of 7.5 because everything up to that was blown. Well in the end the lamp turned red hot and melted some of the components of the dome light piece ( wires running up to it seem undamaged when I removed the dome light housing ). When the fuse was blown, by clock, dome light, and trunk light did not work. When I replace the fuse the clock starts to work, and so is the trunk light; whenever I try to plug something into the domelight, it blows the fuse. I am out of options ( and I do not want to go to the mechanic yet ) so please suggest what may be going on with the system. Also, my automatic light stopped shutting off automatically as I close my drivers door.

 

Is this the light on the headliner with the On/Off/On with the door open switch positions?

You have removed the dome light fixture?

The dome light is powered by a red wire. One end of the bulb socket always has power.

The dome light has an On/Off/On when the door is open switch on the fixture.

When the switch is turned to On, the non-powered end of the bulb is grounded to the chassis at the fixture to complete the circuit.

When the switch is turned to Off, the non-powered bulb end is left open, not connected to any circuit or ground.

When the switch is turned to On when the door is open position (Door), the non-powered end of the bulb is connected to a integration relay and then to the door switches. When the door switches closes (door is open) the switch is closed and the light is powered.

The red wire is powered, the bulb in the ON position just connects the bulb that is always powered to ground inside the fixture.

The Dome fuse powers a LOT of circuit including the auto light shut off. Sometimes the Dome fuse is the only fuse powering a circuit, sometimes it is one of several fuses powering a circuit.

I suggest you not keep increasing the fuse amperage as this can cause fires.

Find out with the Dome fuse light powers but determining what does not work when the fuse is blown, then investigate each circuit for a short.

Given the above info try to determine what happens when the dome light switch is placed in the various positions. Is there only one position where the fuse blows?

If the fixture is unplugged from the power wire and the fuse does not blow, then blows when the lamp installed there may be problem with the bulb socket. Installing the bulb may complete the short circuit.

 

When the fuse is blown, the dome light, clock, trunk light, glove compartment, and ignition light doest not work. When fuse is changed, everything above works, but the dome light ( seem like there no power goes to it what so ever; I measured it and it reads something like .002V. ) Now the new thing I noticed is that my headlight do not automatically shut off... i dont know if thats a by-product of the problem. Now back to the dome light. Its weird when I was measuring whether any vlatage was going through the wires: when the fuse was blown the voltage was .060V and when its replace there is almost no juice in the wires (.001/.000V). Tha confused me a little. So I am not sure whether its the fuse or the wiring or the housing/switch problem, and whther its something I can fix on my own.

 

You stated the fuse only blows when the dome lamp is connected. That you removed teh dome lamp holder.

If the fuse does not flow with the dome lamp out of the holder and blows when installed check the holder for a short to chassis.

The Dome fuse also powers the auto light off device. If blown this device may not work.

 

Well I have explained what all I did to isolate the problem. The fuse right now is new and is not blown so everything it powers works except the dome light which does not seem to get any power to it. I checked the holder, and some plastic was melted due to when the bulb heated up. I have examined the wiring and the metal progngs and they do not seem to touch each other to make any short circuit. The switch on the dome is fine I did not see any damage on the inside of it at all.

 

If possible disconnect the power wire from the bulb fixture. If the voltmeter has an ohm function check the resistance between where the power wire attached and chassis. Determine if there is a short between the connections.

The fixture should not be melting in normal operation.