Tail light fuese keep poping

[Voltmaster]

Hey guys,

So my tail light is not functional , the fuse pop immeditley after turning on the head lights.

I thought maybe bad bulb so i disconnected EVERY connected in the back . the fuse still goes . I think its a bear wire , but i striped the whole trunk I cant seem to find it by looking at it.

Does anybody have any tips or anywhere else it could be?
The first time i notice it happening was on way back from LAS VEGAS when the christmas lights stoped me to tell me it does not work , the back was full of [censored] so i think something happend.

thanks

 

[JimPghPA]

Could be a bad socket for one of the bulbs.

You should include details of the vehicle: year, make, model, and any other specifications such as extended cab, trailer towing option, exc. Such information may get you a specific answer from someone here on BITOG.

 

[bvance554]

The only tip i have is find a friend, relative, or coworker who knows electric wiring and schematics really well. Find a wiring diagram and ask them to trace it down. Worked for me. It could be a bare wire but probably not in your trunk. It could also very well be something completely unrelated that is causing the fuse to blow. Thats where the wiring diagram and knowledgable friend help.

 

[JimPghPA]

I have known some who the first thing they would do with something like that would be to remove any after market wires such as add on lights, add on alarm, and anything else that has any wire that did not look factory.

 

[JimPghPA]

If you turn on the running lights and not the head lights, does the fuse still pop? If so then the running lights circuit would include any wire connections and socket/plug for a trailer if you have that connection.

Some vehicles have an add on box to combine the taillights of the vehicle into the required power for single bulb on each side of the trailer. And if your vehicle has that add on its wiring or box could have some problem.

This is all just a guess, without the specific details (such as schematic), including add ons it is all a shot in the dark regarding any suggestions about what it could be.

 

[Voltmaster]

Originally Posted By: JimPghPA
If you turn on the running lights and not the head lights, does the fuse still pop? If so then the running lights circuit would include any wire connections and socket/plug for a trailer if you have that connection.

Some vehicles have an add on box to combine the taillights of the vehicle into the required power for single bulb on each side of the trailer. And if your vehicle has that add on its wiring or box could have some problem.

This is all just a guess, without the specific details (such as schematic), including add ons it is all a shot in the dark regarding any suggestions about what it could be.



The running lights are automatically turned on after 3 seconds of engine start with no way of turning off. The fuse does not pop until i turn on the headlight manually.

I dont have add on box... I got two diffrent haynes manuals no luck of finding out what wires goes where.

 

[Voltmaster]

Originally Posted By: JimPghPA
Could be a bad socket for one of the bulbs.

You should include details of the vehicle: year, make, model, and any other specifications such as extended cab, trailer towing option, exc. Such information may get you a specific answer from someone here on BITOG.


06 corolla CE

it cant be a socket because i disconnected ALL connection for every bulb in back and still tripped immediately.

 

[NHGUY]

I believe there may be a small box in the trunk that acts as a junction or resistor of sorts.I have seen that on older Camrys.Maybe its fried?

 

[The_Jeff]

The parking light circuit also runs all your gauge lights and the light in the radio. When someone monkeys with the radio wiring this light and resultant fuse can be affected.

If you can get at the dash light dimmer and pry it out and disconnect it, that should eliminate a big opportunity for shorting for diagnostic purposes.

 

[mechtech2]

With the lights off, check for shorts in the socket with a multimeter set to resistance. The 'hot' is probably shorted out. But this does not mean it is IN the socket, it may be a connector or a wire downstream.

 

[JimPghPA]

I have an old Keithley 191 digital volt ohm meter that measures down to 1/1000 of an Ohm, and down to 1/100000 of a volt on the 2 volt scale. With that you can measure the resistance of a wire. And because a wire has resistance the further away from a short you get with it, the more the resistance increases. And the closer to the short, the lower the resistance gets. You can locate a short between traces inside of a multi-layer circuit board with that meter. And I have use it for that several times with new boards.

What I am getting to with this is that you can make an equivalent for your application.

Replace the fuse with a small 12 volt bulb, like a small 12 Volt dash light bulb. To do this just take a blown fuse and break away enough of the plastic to solder wires that you connect to the small 12 volt dash bulb, so you can insert the fuse in the regular fuse socket with the wires connected to the bulb. That way you will get some current (a limited safe amount limited by the resistance of the small bulb)to flow through the circuit in question. A digital volt meter with reading down to 10 millivolt (or even down to 1 millivolt would be better) on the 2 volt scale would be easier to find, than a Ohm meter with high resolution like my Keithley 191.

And with the current from a small 12 volt dash light flowing through the wires and the short in your truck, you should be able to trace the voltage drop of the wiring. If you start at the small bulb feeding the wire where the fuse normally would feed the circuit, you will probably see something like fraction of a volt with respect to ground.

It probably would be a good idea to make up a long fairly heavy ground wire for the meter so you do not have to remove the meter ground connection as you move the meter + connection around to trace the wiring until it leads you to the problem. With the stable long ground connection for the meter, the ground reference for the meter will remain constant and the reading you get as you move the + to trace the problem will provide accurate information about weather you are getting closer or farther away from the short. And as you get closer to the short, the voltage reading will become lower.

The small bulb feeding a small amount of current instead of the fuse should be a safe way to introduce a limited current to the circuit so you can trace down the problem. But just to keep it safe, do not leave that feed connected with no one around, and be on the look out for any smell of an electrical problem. If you really want to play it save, you could include a fuse in series with the small bulb.

PS, maybe post how this works for you if you try it. It should work.

 

[JimPghPA]

You can use a regular pin or a hat pin to get through the insulation to tap it for the + probe of the meter for the reading as you progress through the wiring in the vehicle.

 

[JimPghPA]

A last resort would be to go to a junk yard and find a similar vehicle that has enough damage that the junk yard would not mind you damaging the wiring as you rip through it to trace where everything goes. You might find some hidden and good electric control box while you are doing that. Some junk yards are you pull it, and others wont let you near a vehicle.