Circuit Deactivation Ignition Module (CDIM)

Vehicles equipped with a 6.7L diesel engine may also be equipped with an extended idle shutdown system. This system is controlled by the PCM and uses several inputs to determine whether or not to shut the engine off. The CDIM disables the ignition switch circuits after the PCM has shut the engine off. For a complete description of the extended idle shutdown system and related components, refer to the INTRODUCTION - DIESEL MODELS .

Once the PCM has determined that the engine should be shut down, it sends a message to the IPC along the HS-CAN. The IPC then sends a message to the CDIM along the MS-CAN. Once the CDIM receives the message from the IPC, the CDIM begins a 60 second timer and monitors the MS-CAN for ignition switch position, brake pedal position and engine RPM. If the RPM remains at 0 and both the ignition switch and brake pedal switch remain undisturbed for 60 seconds, all CDIM internal relays open and the vehicle enters into the standard accessory delay. If one or more of the monitored signals changes during the 60 second time period, the CDIM internal relays remain closed, allowing voltage to remain applied to the ignition circuits.

To reactivate the CDIM and ignition circuits after the engine shuts down, the ignition switch must be turned to the OFF position before attempting to start the engine or before the ignition switch is turned to any other position.

If the vehicle is getting the extended idle shut down system installed at a dealership as opposed to the assembly plant, the PCM must be enabled. To enable the PCM for extended idle shutdown, refer to the Extended Idle Shutdown Initialization General Procedure in ELECTRONIC ENGINE CONTROLS - DIESEL ENGINES .