ELECTRONIC CONTROL SYSTEM PDC# Device X1 X2 X1 X2 X3-3 V IGN F4 F12 F41 F46 R 30A...IDM/ECM 20A...RUN/ACC 10A...ECM PWR 5A...ECM KEY PWR ECM RELAY - POSITION 50 ECM X3-5 ECM MPR X3 X4 X3 X4 X4-1 ECM PWR 1 X4-2 ECM PWR PDC 200 A F4 TO IDM RELAY TO ENGINE INLINE 12-WAY F41 R 3 1 5 BATTERY F-46 1 2 STARTER MOTOR RELAY KEY SWITCH F-12 ECM Relay Circuit Operation • The ECM controls its own power up and power down process. When the key is OFF, the ECM stays powered up for a brief period. The ECM then powers down after internal housekeeping functions have been completed. Pin 2 connects the coil to pin X3-5 of the ECM.
Shut Down When the key is OFF and voltage is removed from ECM pin X3-3, the ECM shuts down the engine but keeps the ECM powered up briefly until the internal house keeping is completed. When the key is ON, voltage supplied to pin X3-3 signals the ECM that the operator is going to start the engine. The ECM then supplies a ground circuit to pin X3-5. When this occurs, current flows through the ECM relay coil and creates a magnetic field causing the relay to latch. When latched, the relay connects pin 3 to pin 5 and supplies current to the ECM through pin X4-1 and X4-2.
Key Power The Run/Accessory position of the key switch receives battery voltage from the Power Distribution Center (PDC) fuse F-12. When the key is ON, the switch supplies battery voltage through fuse F46 to ECM pin X3-3. Battery voltage is available at all times through fuses F4 and F41 to ECM relay pins 1 and 3. The two fuses are in series, with F4 feeding both the IDM and ECM relays, and F41 dedicated to protecting the ECM circuit alone. Pin 1 supplies voltage to the relay coil. 27 International ® VT 275 V6 Engine