This volvo came to our workshop with a drivers door issue Nothing electrical worked on the door including window, mirror and locking Customer had changed module in door with no affect.we checked all powers and grounds they were OK. Then we checked the linbus signal to the module and found it open circuit. Tracing the wiring to the door we found this corrosion on the wirer. Very small but significant. Wirer was repaired and the signal restored With signal restored the door worked perfectly.