A method for manufacturing a blind spot indicator module for a vehicular exterior rearview mirror assembly includes providing a housing, a rear cover and a circuit board. The circuit board is disposed at the housing and the rear cover is attached to a rear end of the housing to encase the circuit board, whereby electrical terminals extending from the circuit board are disposed between a first connector portion of the housing and a second connector portion of the rear cover, thereby forming an electrical connector configured for connection to another electrical connector for electrically connecting circuitry of the circuit board at least to electrical power when the blind spot indicator module is used by an exterior rearview mirror assembly that is attached to a vehicle. The circuitry includes a light emitting diode that emits light when electrically powered, and a diffuser element diffuses light emitted by the light emitting diode.