Problems with dome (interior) and maps lights in my 9-3x

Despite many hours of diagnosing and frustration, I haven't been able to figure out why the interior dome lights, map lights and vanity mirror lights in my '10 9-3X are very dim. (The footwell lights, door lights, and lights in the cargo area work as they should.) Also, as each additional light in the circuit is switched on, the lights that are already on dim even more. This would obviously point to a grounding issue. However, I have checked and cleaned the grounds in the cargo/trunk area. I have also checked and replaced fuses, replaced and reprogrammed the BCM twice, and checked the wiring in the headliner and A-pillar. Now that the BCM and the wiring in the headliner and the A-pillar have been seemingly ruled out, I am not sure where to go next. Door modules perhaps? It occurred to me yesterday, that this problem may occur with other GM cars since they share components across platforms. These bloody can-bus systems which rely on computers are super tricky to work on and diagnose. Thanks, Chris

Not to rule out the bloody can-bus system, but I have come across virtually same problem as described in GM, Fords, Chryslers and it is almost always a bad power wire connect problem. If there is only one strand of a multi stranded wire connected, the wire will test good for continuity and voltage, but not carry enough current to power the circuit. Before you start pulling your hair out, pull on the power feed to and from the fuse to the first light in the circuit. If the wire end pulls off, or the wire pulls apart, you have found your problem.