ELECTRONIC CONTROL SYSTEM PDC# Device X3-8 IDM LOGIC POWER X3-24 IDM MAIN POWER X3-25 IDM MAIN POWER X3-4 IDM MAIN POWER X3-23 IDM MAIN POWER X3-27 IDM MPR X3-7 V IGN F4 F12 F40 F46 R 30A...IDM/ECM 20A...RUN/ACC 10A...IDM LOGIC 5A...ECM KEY PWR IDM RELAY - POSITION 55 X1 X1 X1 X2 X1 X2 X2 X3 X2 X3 X3 X4 X3 X4 2 IDM ECM PDC BATTERY 200 A F4 30 87 R 2 12 TO IDM RELAY F40 6 F-46 85 86 8 9 ENGINE IN-LINE 12-WAY STARTER MOTOR RELAY KEY SWITCH F-12 IDM Relay Circuit Operation • The IDM controls its own power up and power down process. When the key is OFF, the IDM stays powered up for a brief period. The IDM then powers down after internal housekeeping functions have been completed.
When the key is ON, voltage supplied to pin X3-7 signals the IDM to provide a ground circuit to pin X3-27. When this occurs, current flowing through the IDM relay coil builds a magnetic field that causes the relay to latch. When latched, the relay connects pin 30 to pin 87 and supplies current through pin 12 of the engine in-line 12-way connector to pin X3-4, X3- 23, X3-24, and X3-25 of the IDM. Four pins receive voltage to spread the current draw over multiple pins. IDM Logic The IDM also requires voltage for the internal logic circuit. When the IDM relay latches, pin 87 of the relay supplies voltage to the IDM logic circuit through the F-40 fuse in the PDC.
The F-40 fuse feeds through pin 6 of the engine in-line 12-way connector to the IDM pin X3-8. IDM Power Up The key switch receives battery voltage from the Power Distribution Center (PDC) F-12 fuse. When the key is ON, the switch supplies battery voltage through F-46 fuse and pin 9 of the engine 12-way connector to pin X3-7 of the IDM. Battery voltage is available through the PDC F-4 fuse to IDM relay pin 30 and 85 at all times. Pin 85 supplies voltage to the relay coil. Pin 86 takes that voltage through pin 8 of the engine 12-way connector to pin X3-27 of the IDM. 28 International ® VT 275 V6 Engine