Odd problem with radio and domelight on 2009

[Thymeclock]

Success! I found a solution but I still don't know the cause of the problem.

It occurred to me that since all the other door switches have two wires, and they all activate this circuit, if I could tap into it then the driver's door switch should also work. I noted that one of the wires on the other switches appears to be cream white in color. I located one of that color in the bundle under the threshold of the driver's door. Using a needle pick probe I verified that it was live at 12V. The purple wire that goes to the driver's door switch had a reading of only about 1 volt (although it should have had 12V). The next step was to run that probed wire to ground, and hope that it wouldn't blow a fuse or do anything nasty. When I did, the dome light was activated. Hooray!

The next step was to verify the purple wire as the correct one leading to the switch, as there are two purple wires in that bundle. A continuity test showed that both were continuous with the one that was attached to the switch. Then I needed to bridge the purple with the white wire in the bundle. Since I don't like cutting into wires unnecessarily, I took a 3M tap connector and cut away the portion of the plastic that would usually be used to join a running wire to a single wire. In other words, the clip in the tap would now be used to bridge the two wires without cutting them. I installed the bridge and it works.

But without a schematic, I still have no clue as to what was causing this problem. The problem remains, but the workaround provides a cure.