Fuse question

[GMCjunkie]

Hey y'all!! My tail lights weren't working, I discovered that I had a burnt fuse and changed it. Tail lights weren't working again, another burnt fuse. I went and bought new 20A fuses and as I went to put it in, as soon as it touched the fuse box it sparked and burnt again. I didn't even push it in to the thingie. What in the heck is going on?? Any insight is greatly appreciated. Thanks!!!
junk

[SS Tim]

Its a basic problem, you have a direct short. That means something in that wire circuit that is normally insulated is contacting a ground and overloading the fuse. Generally a worn or otherwise damaged wire would be my first guess on this. If you have a trailer pigtail start there. Sorry there isn't an easy way for me to tell you all the steps to finding the problem.

[SS Tim]

Prooblem is there are several circuits all powered/protected by that fuse. Here is an example from a service manual. It could be any of them.

Now that I think of it, was anything "on" when you replaced the fuse? With the truck cold and parked the only circuit pulling from that fuse would have been the dome lamps when you opened the door/s (if so optioned).

[GMCjunkie]

Thanks Tim, there shouldn't have been anything on. I didn't even have the key in, and my dome light isn't hooked up. I will have to call my son to help me with this one I think. I will show him your information and hopefully we can trace the problem. Thank you so much!

[SS Tim]

If that is the case then maybe start with the circuits that are always hot. What I mean is powered all the time by the battery. Examples of these are the feed wire to the brake light switch. The dome lamp power wire (its always hot and the switchs ground the lamp circuit to illuminate). The marker lamp feed to the headlamp switch is another possibility.

If you have a factory manual the schematics can help in running down the wires and colors. Just remember your ride old and they are rarely "stock" anymore.

* VIN/Model Decoders
* Power Team Charts (engine/transmission/gear ratio)
* Post Your Pickup SPID Blazer SPID Suburban/Panel SPID
* RTFM ... Read The Factory Manuals... download 'em here

[SS Tim]

Was just looking something else up and wanted to suggest that you look at 12-33 and 12-34 in the downloadable 72 chassis service manual.
This will give you a good breakout of the harness at the instrument panel. From there you can go back to the taillamps as well with the rear body harness drawings. Remember 06&16 will be applicable model codes for your burb.

[GMCjunkie]

Yes sir! Thanks so much for the info!!

[GMCjunkie]

SS Tim I think I got it!! It was one of those middle of the night, laying awake things. You said that there has got to be something touching that was normally insulated. All I could think of was my dome light wires, Ive never hooked up dome light, because I still have to finish my headliner. I taped those wires, but that was soooo long ago. I went out and checked and sure enough, the tape had came loose/unstuck from the ends and I had them tucked in at the edge of my headliner bracket. I taped them back up and put another fuse in and PRESTO!!!! so far so good!!! Thanks so much for your help!

hugs,
junk

[SS Tim]

Sounds like you might have fixed the cause at least for now. Might want to consider making a bracket to hold up the dome lamp until you reinstall a headliner. Then yo can enjoy the benefits of it. Maybe even add in a set of the underdash courtesy lamps with one of Rodger's kits.