Repairing Your Porsche 928 Central Warning System CWS Controller

Repairing your Porsche 928 Central Warning System (CWS) controller. This procedure is for a 1984 Porsche 928 S controller. Under the left foot pedal (dead pedal) of the Porsche 928 lives the Central Warning System (CWS) controller. This miracle of 1980’s electronics takes the inputs from the sensors on you 928 and compares them to a reference or another input and then drives the instrument bulbs in the pod cluster that illuminate the warning indicators on the dash display. The system is implemented in an aluminum enclosure ~ 3.5” x 5”x 2” that contains 2 connectors. Each one of the connectors is soldered to a circuit board inside the unit and the two circuit boards are connected together using three flexible printed circuits. One circuit board contains a D8748 8-bit microcontroller. This controller has an 8-bit CPU, 1K x 8 of EPROM memory that stores the code that runs the system and 27 I/O lines that provide the sensor data to the microcontroller.get