The function diagram for ECM PWR includes the following:
• ECM main power relay
• Ignition switch or power relay
The Electronic Control Module (ECM) requires a 12 V power source to function correctly. The operating
power is received from the vehicle batteries through the ECM main power relay contacts each time the
ignition switch is turned ON.
When the ignition switch is turned ON, the ECM provides an internal ground to the coil side of the
ECM main power relay. This closes the relay contacts and provides the ECM with necessary power.