Bootlid central locking system motor (184H): Connect: Switch

Pin 2 is ground from the rear electrical center in the luggage compartment and pin 1 feeds with 10.2V via an resistor of 680O integrated in BCM. The voltage measured across the pins will be approximately 4.1V when the breaker is made and approximately 7.4V when open. If the control module sees 10.2V or 0V it will be interpreted as an error in the circuit.

In order to save current when the car is not driven BCM will pulse the voltage to the switch for 2.5 ms at 375 ms intervals as soon as the car's bus communication stops.

Fig 1: Identifying Communication Flow - Bootlid Central Locking System Motor

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fig 2: Circuit Diagram - Bootlid Central Locking System Motor

Courtesy of SAAB-SCANIA OF AMERICA, INC.