CAN communication from manual gearbox or OPC One of the CAN messages expected from the GMS control unit disappears or is missing. In vehicles with OPC or manual gearbox with acknowledgement for engaged neutral in the main gearbox, the clutch pedal must be depressed before changing gear in the transfer gearbox. The fault code is generated only on vehicles with acknowledgement for engaged neutral in the main gearbox. If fault codes 11060, 11070, 11090, 11100 and 11110 have been generated, there is probably an open circuit on the CAN cable to the AWD control unit. In vehicles with manual gearbox, the coordinator functions as a transmission control unit and transmits these messages.