Tail lights not working . HELP!!

[Zo6_shawn]

Ok so I’m hoping I can get some help here .. however I’m not working on a tahoe at the moment but a 2003 Silverado , which the electric is very similar .. anyway let me explain

So my tail lights are not working , I do have turn signals , brake and reverse working fine .. it’s only the running lights ..

So this is what I’ve done so far..
I’ve checked all sockets
Checked and replaced junction box on frame .
Tested all wires leading to the light and all have power but the running lights ..
all fuses are good .. checked the ground on the rear of the truck near the rear axel above the spare tire ..

So I’m losing power for that circuit between the fuse box and rear of the truck.. I don’t know where to start

Let me also say that the truck was painted and this is how I picked up the truck .. so the bed was moved to paint the back of the cab .. maybe a short along the frame from removal ??

Any help would be great

 

[rockola1971]

If you dont have 12v at the harness at the rear but you do at the fuse then you have an OPEN not a Short. Your wire is broken or a connector is disconnected (same as is). This may also be BCM related but id have to have a look at a schematic for your setup.
People confuse a short, short to ground with a term many dont know ...Open. A short to ground means the 12vdc is going to ground BEFORE it gets to its load (light bulb, starter, relay coil, fuel pump motor, etc.). When this happens (a wires insulation is rubbed open and the wire touches chassis ground is a good example) the current flow to ground is infinite until it exceeds the fuse rating for that circuit. The fuse pops and done. So if the fuse is good then you dont have a short to ground.
A "short" when used properly as a term means some of the load is bypassed. A good example of this is a ignition coil partially melts. When new its total resistance may be 40ohms but when some of its coils melt together the overall resistance ends up being 12ohm because many of its coils are now bypassed. This causes the current flow to rise (by over a factor of 3 in this case) because resistance goes dowm, current goes up. The windings are rated for a certain amount of current (not a factor of 3) so immense heat builds up and the coil catches fire and it all melts inside. This was NOT a short to ground.

If I come up to your vehicle and cut your 12v+ battery cable 1ft away from your battery I just opened your 12vdc+ circuit. It now has an electrical open. When a light bulb blows it is now an electrical open.