When the headliner was replaced by the PO, who ever did it reconnected the front dome light incorrectly (*see below). While the ON mode worked, the AUTO mode did not but I didn't notice as I had immediately switched to LED internally when I got the car (LED's don't dim with the stock dimmer module).
I installed BitSyncMaster's "dome light dimmer/parade" module ready for the 4th July parade. BitSyncMaster was very kind in helping me diagnose my mis-wired front dome light, which since it wasn't wired correctly didn't let the module work correctly. Many kudos to BitSyncMaster
Everything is working perfectly just in time for the 4th July
* Toggle was connecting Purple to Ground (ON) and Purple-White to Ground, instead of Purple to Ground (ON) and Purple to Purple-White (AUTO).