Do you know how to use a wiring diagram? If you choose to understand how to fix this rather than throwing parts and time at it, I would suggest getting a diagram and finding your problem. This is about as simple a system as there is. Power starts at the battery positive and ends at the battery negative. In between is a system of fuses, connections, relay/s, switches, connections, and motors and wiring. Start at the beginning and follow the path.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician