Hi aceee,
If you look at the bezel (Lamp assm.) there are five wires; Red, Yel, Blu, Grn, and White w/Blk marker. The BLUE wire feeds the stop light, and the White w/Blk stripe is the ground. Get hold of a test light (Auto-Zone $4.99) or multi-meter. You need to prove the HOT and the GND to find the culprit. Remove the Double filament bulb from the socket and see the copper contacts inside of the lamp socket. Try to determine which one is the HOT and which is the GND; the colored wires will usually be adjacent to their prospective copper contact. For these tests, wrap the test light's metal probe with vinyl electrical tape to prevent popping a fuse by accidentally short circuiting the probe while working inside of the socket!
Using a KNOWN power source (like the rear 12V receptacle with vehicle IGN ON) connect the 'alligator clip' end, to the copper contact (GND) directly adjacent to the White/black wire inside of the stop-lamp socket, and touch the probe's pointed end with the center copper contact inside of the 12V socket. If the test light, lights up then the ground isn't the problem. Now to test the power supply of the stop-light. With the alligator clip connected to a KNOWN working GND (perhaps a bolt or screwhead at the tailgate latch assembly), touch the pointed end to the copper contact directly adjacent to the BLUE wire inside of the stoplight socket. If this doesn't work, try piercing through the blue insulation directly on that feed wire.
If this time the 'test light' lights up, then the problem is your Blue wire power supply to the stop-light socket. So at very least now you know which part of the electrical circuit is the problem! Just as [MENTION=65614]Antman[/MENTION] alluded to in his earlier post, it may be time to 'dig in' and start taking the electrical socket apart to get at the true problem e.g., broken wire, bent copper HOT contact, dirty ground contact...etc! I know you've checked the fuse and proved the bulb earlier, so your problem is somewhere in that socket assembly, you may even end up replacing it; autozone has them on their turn-style socket display, not expensive at all! please be sure to let us know what you find; someone else here will certainly struggle with this same trouble, 'Best'
rig!
Thanks so much for the info. I will give that a shot this weekend and post back with results.
