I recently had a battery charging problem on my 2003 Rubicon and solved it by installing a new rectifier/regulator. In the process, my digital display (combination meter) has gone completely out. It worked fine before I switched batteries and rectifier, now it is out, like it is not getting power. Everything else works: lights, accessory plug, even the back light in the display. I have tested all fuses. There is one component in the fuse box that I can not identify. It is a black, 3-pronged, plug on the bottom right, inside the fuse box. It is not labeled or listed in the manual. Anybody know what it is and could that be my problem? I thought it was the main breaker but the engine runs even if it is out. I put a meter on it and it doesn't appear to have continuity. Any ideas? I've got pictures of the thing.

Thanks