11 SILVERADO 2500HD 6.0 W 4;10 USING A MIUTE MOUNT 2 . WHEN PLW IS PLUGGED IN NDER THE HOOD MY LIGHTS DO NOT WORK. WHEN IT IS UNPLUGGED THEY WORK FINE. WHAT DO I LOOK FOR

Check for that fuse in a fuse panel under the dash.
That second wire from the old light is a ground wire, whereas the new light's socket is case grounded if there is no ground wire for the light. If the fuse for the tail lights is good, check if the tail lights lost a ground .

First check the fuse(s) under the hood, fuse box on drivers side, location of fuses on inside of fuse box cover, if fuse is good,then check for power to the fuse (test light) make sure it is connected correctly. If all is good the you will have to replace the plug assembly there is NO repair. Make sure it is a power plug and NOT a cigarette lighter plug.

Check the brake light relay in the box under the hood.

Please see my tip at http://www.fixya.com/cars/r6053280-lights_out_lights_not_out_bulbs_ok and let me know if you have questions.

Did you check for voltage at backup lamp fuse, use a test light. The actual diagram I copied was larger than this and easier to read. This must be a site issue, common to fixya. You could even use a long piece of jumper wire from battery voltage to light green trailer wire, to see if lamp will light. It would'nt hurt to use inline fuse, for testing. If lamp still won't work, maybe problem with trailer wiring. You could even use jumper wire to bypass the connector itself, same color wire?

Most likely the blower motor resistor. It's mounted next to the blower motor under the dash. Also check the 7 wire plug going to it, GM had a problem with that plug, and the wiring getting hot and melting. The plug is $68.00 from the dealership. One of my customer's car had the same problem.

same bulb but 2 seperate elements. wiring diagram u should be able to obtain from your local auto parts store like autozone(preferred)

Blinking or chattering of the compressor clutch usually indicates low "freon" charge.

I am having the same problem on an 04 2500hd there isa 15 amp stop light fuse inside the cab on the side of the instrument panel and a 25 amp stop light fuse under hood. you could also have a break switch issue the switch is located up on the break pedal linkage you should have power on the white wire when you push the pedal in (check with a test light) in my case I have a broken wire along the frame rail in the harness it is a light blue wire,

your truck has fuses for the rear and high mount brake light in the fuse box in the side of the dash when you open the drivers door

You may have faulty wiring for your trailer lights. Look under the back of the truck where the wiring harness leads to the trailer wiring harness. Usualy it is a 3 way plug in the harness. Try unpluging the harness from the trailer wiring and just plug the other 2 wires into eachother
Hope this works for you!