Can someone help out. My brother has a 99 Tahoe and the rear tailights wont come on (brake and running) the CHMSL ( third brake does comes on). This all started when he removed the front bumper to have it powder coated and also changed the fuel pump. He has it a local shop that is pretty good with this type of thing, but has had no luck finding the problem. I know it's hard to pin point without the vehicle, but was wondering if anyone had a similar problem and could share their ideas.

Just found the problem. When he dropped the gas tank he pulled a plug in the wire harness along the frame rail. The guy that was fixing it said he had a hard time seeing it just felt around and clipped it together and bingo lights.