Windshield Frame Lock Drive Hall Sensors

Two hall sensor switches are installed on the left side top lock drive assembly. Both sensors receive power and ground from the CVM. One switch is the soft top locked to the windshield frame (S142 cowl locked/locking hook closed). The second switch is the locking hooks of the convertible top open (S145 cowl released/Locking hook open). As the slide assembly on the worm gear moves, it covers and uncovers the hall sensors to cause the high/low switching to take place.

The "Locking hook closed" (S142) input provides a high signal when the top frame is locked and a low signal when it is unlocked from the windshield (LED in the soft top switch will start to flash).

The "Locking hook open" (S145) input provides a high signal when the top frame is raised past the tension point.

Fig 1: Identifying Windshield Frame Locking Hook Hall Sensors

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Circuit Diagram - Locking Hook In Closed And Released Positions

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: The Diagnosis Requests list in Control Unit Functions refers to a "CONVERTIBLE TOP LOCKED" switch input (S141). That display is a redundant signal from switch S142. Production E46 Convertibles are not fitted with S141.