AUTOMATIC TRANSMISSION – ZF HP 44-2-36 DESCRIPTION AND OPERATION Inhibitor Switch The inhibitor switch is located externally on the right hand side of the transmission. The switch is located on the selector shaft and secured to the main casing with screws. A protective cover is also fitted over the switch to prevent impact damage. The switch rotates with the selector shaft, moving the switch contacts to correspond to the selected programme. The switch provides signals which allows the EAT ECU to monitor the position of the manual selector spool valve and the selected drive programme. The switch is connected via an integral harness and multiplug on five wires to the EAT ECU. One of the wires supplies a V supply to the switch. The remaining wires are connected to the EAT ECU. When the transmission selector lever is moved to the selected position, one or more of the contacts within the switch are made, completing a circuit back to the ECU. From the switch contacts which are made, the ECU determines which selection is required and responds accordingly. When the selector lever is in Park, the EAT ECU transmits a signal to the immobilisation ECU to enable starter operation. The signal also energises the starter relay, allowing the crank signal from the immobilisation ECU to pass to the starter solenoid. The following table shows which switch contacts are made fora given selector lever position.