Is the third time break light on a 2008 Malib LED?

check fuses and connections --dead battery--

It seems like the connection is interrupted in the trunk check the wiring

LED,s use different power consumption a normal globe. The brake lights on your car may use the same power supply as the airbag system. Try putting the original standard globe back in. If the airbag light goes out, then that will be the problem. you will not therefore be able to use the LED in that brake light.

LED bulb under ruber gasket

Sounds like a problem with the turn signal switch. The third brake light bypasses that switch.

Checxk for loose wires, Or a break min a wire,

Hi William, To begin, the usual color coding on American vehicles is black is ground. To test this, take a long length of cable and a test light. Connect one side of the test light to battery positive and and the other cable connect to the black wires one at a time. If the light comes on normally you have proved the ground connection, then do the same with the other. Next connect the test light to the green cable and the other cable to the black. Press the brake pedal and observe if the light illuminates. If all is well, connect the black cable from the third brake light to the black cable of your car and the red cable from the after market brake light to one green cable from your car an insulate the other. Then go ahead and mount the third brake light. Regards John

its an led assembly dealer only will sell you the whole light, unless your a wizz at soldering and testing for the right resistors this is the only fix

The third break lights are LED and the circuit board may have gone bad or the solder may have gone bad. The circuit board is built in the third brake light and is a seal unit. You may have to replace the unit, there is a relay for the third brake light and that is located on the glove box behind the panel that say's relays. There are three relays in there, the center is for the fuel pump and the two out side are for the A/C and third brake light. Just swap them around and see if the brake lights come on. Good luck and keep me posted. 

if its the same as an 06 Tundra, you should be able to remove the lense cover from the back of your truck cab with a screwdriver and pull the light bulbs out...Do not remove the screws below the lense cover that removes the fixture, they have a screw insert that will fall into your truck's body and get lost.....hehehehe I learned that from my own experience...good luck!