: Useful if the connector pins are just dirty or slightly corroded.
: Moisture ingress in the electrical connectors behind the mirror assembly or inside the door panel.
When replacing these drums, always prioritize quality. Cheap, no-name drums are prone to warping and imbalance. Stick with the cross-referenced brands listed above (Dorman, Raybestos, Centric) and always replace drums in pairs (left and right rear) to ensure balanced braking.