The function diagram for the ECM / IDM communication system includes the following:
• Exhaust Gas Recirculation (EGR) drive module
• Crankshaft Position Output (CKPO) signal
• Camshaft Position Output (CMPO) signal
• Controller Area Network (CAN 2) datalink
• ENGINE lamp (amber)
The ECM provides two output channels to aid the IDM with engine speed and position signals. The CKPO and CMPO channels are in phase with the CKP and CMP signals received by the ECM.
The ECM and IDM are in continuous communication.
The CKPO and CMPO signals are generated when the ECM switches these circuits to ground. The IDM
uses these signals for engine speed and timing.
The CAN 2 datalink is a bidirectional communication line between the ECM, IDM, and EGR drive module.
The ECM, IDM, and EGR drive module use the datalink to send operating strategies, sensor information, diagnostic demands, and Diagnostic Trouble Codes (DTCs).
NOTE: The engine will not operate without the CAN 2 datalink, CKPO, or CMPO signal.