The IDM is grounded to the battery negative terminal at IDM Pins X3-1, X3-2, X3-3, X3-22 and X3-26.
The IDM receives VIGN power at Pin X3-7. The power signals the IDM to provide a ground path from Pin X3-27 to 85 to switch the IDM main power relay.
Switching the relay provides power from the battery positive terminal through a fuse and relay contacts 30 and 87 to Pins X3-4, X3-23, X3-24 and X3-25.
Switching the relay also supplies power through a fuse to Pin X3–8 logic power. See truck Chassis Electrical Circuit Diagram Manual for circuit numbers, connector and fuse locations.
Fault Detection / Management
The IDM internally monitors battery voltage. When the IDM continuously receives less than 7 V or more than
16 V a Diagnostic Trouble Code (DTC) will be set.
IDM PWR Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the flashes from the amber and red ENGINE lamp.
DTC525
IDM fault
• DTC 525 is set by the ECM when there is an internal IDM failure. When DTC 525 is set, replace the IDM.
• When DTC 525 is active the amber ENGINE lamp is illuminated.
DTC 523
IDM VIGN voltage low
• DTC 523 is set by the ECM when the voltage from VIGN is less than 7 V.
• DTC 523 can be set due to poor connections between the IDM Pin X3-7 and the VIGN.
• DTC 523 will not illuminate the amber ENGINE lamp
DTC 533
IDM relay voltage high
• DTC 533 is set by the ECM when the voltage from the IDM power relay exceeds 16 V.
• DTC 533 can be set due to an alternator voltage output of 16 V or more. DTC 533 can also be
set when jump starting the engine or incorrect external battery connections exist.
• DTC 533 will not illuminate the amber ENGINE lamp.
DTC 534
IDM relay voltage low
• DTC 534 is set by the ECM when the voltage from the IDM main power relay is less than 7 V.
• DTC 534 can be set due to a poor connections between relay and batteries, poor connections between relay and IDM, a blown fuse, or a failed IDM main power relay, discharged batteries or increased resistance in the battery feed circuits.
• DTC 534 will not illuminate the amber ENGINE lamp.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• Breakout Box
• Relay Breakout Harness
• 12–pin Breakout Harness
• Terminal Test Adapter Kit
