Fault Indication With Serial Data Transfer

Transmission control unit transfers data on the fault indicator line (pin No. 29) relating to the transmission oil temperature and the selector lever coding (4th or 5th gear) to the instrument cluster. The fault light is activated by the instrument cluster when a voltage of 12 volts is applied on this line for longer than one second. This is the case when the EGS control unit is still in its initialization phase (ignition on, engine still not started), or in the emergency program or when the wire has an open (pull-up resistor in instrument cluster).