Tail light fuse blowing

[GMC69]

I went to pick up my new ( to me) 1970 C20 and tried to replace the tail light fuse. It blew right away.

I am just about to start troubleshooting this issue as I just got the truck home. I figured I would see if anyone had suggestions and I can keep checking on my cell, while I trace out the wiring.

The fuse blows just by putting it in, incase anyone was wondering.

[Daddy Brim]

I had the same problem with mine. Check to see if the wires have been hacked. It sounds like you have hot wire grounding out.

[1970 Bowtie]

Had the same problem,PO hack up the rear for trailor lights.His idea of a weather proof connection was electrical tape.I also had a short behind my ds tail light where the hot wire was pinched between the tail light bucket and the body.

[GMC69]

Originally Posted by 1970 Bowtie

Had the same problem,PO hack up the rear for trailor lights.His idea of a weather proof connection was electrical tape.I also had a short behind my ds tail light where the hot wire was pinched between the tail light bucket and the body.

Did your fuse blow instantly when installing it or only when you pressed on the brakes. I thought the tail lights were only hot when the brakes are pressed.

[Daddy Brim]

also check the brake switch it is under the dash on top of the brake peddle

[1970 Bowtie]

Originally Posted by Daddy Brim

also check the brake switch it is under the dash on top of the brake peddle

You beat me to it.Try unpluging the brake light switch and see if it still blows the fuse.

[tr69c10]

I had the same problem mine was the turn signal switch in the column the metal springs things where touching the column housing and shorting out the brake lights dome light and dash lights

[chevytruckluver]

Originally Posted by GMC69

Did your fuse blow instantly when installing it or only when you pressed on the brakes. I thought the tail lights were only hot when the brakes are pressed.

Are you needing help with tail lights (as posted) or with brake lights?

[Longhorn Man]

if the fuse pops as soon as it is installed, then odds are it is the dome light. The dome light stays hot all the time (orange wire) and swiched on the ground side (white wire) best place to look (assuming the light assembly is mounted properly and not broken or dangeling) is under the drivers side door sill plate.

If it pops as soon as you hit the brakes, then check the brake light circuit, if it pops as soon as you turn on the parking lights, then check that circuit.
On the electrical forum you'll find colored schematics.

[GMC69]

Originally Posted by Longhorn Man

if the fuse pops as soon as it is installed, then odds are it is the dome light. The dome light stays hot all the time (orange wire) and swiched on the ground side (white wire) best place to look (assuming the light assembly is mounted properly and not broken or dangeling) is under the drivers side door sill plate.

If it pops as soon as you hit the brakes, then check the brake light circuit, if it pops as soon as you turn on the parking lights, then check that circuit.
On the electrical forum you'll find colored schematics.

Funny you mentioned this. By process of elimination and my meter. I discovered it was the dome light. Ended up that the wires at the plug close to the high beam foot switch were reversed. I pulled them out of the plug and reversed them.

All is good now.


Thanks for all the replies.