ELECTRICAL SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
CAT DATA LINK CIRCUIT TEST
N OT E
· Use this procedure if MSD will not communicate with ECM through data link. If MSD will not power up,
refer to Electrical Power Supply Circuit Test in this work package.
· Use this test if engine monitoring system (EMS) displays error or if incorrect values are displayed. An incor-
rect value may be "0" for engine speed.
· CAT data link is standard data link used by ECM to communicate with MSD.
· ECM provides the following two connections for CAT data link from ECM connector J1:
J1:5 (CAT data link negative) to J20:5
J1:4 (CAT data link positive) to J20:4
· MSD may indicate the following error message: "Version of ECM is not recognized and integrity of changed
parameters and displayed data is not guaranteed." This message indicates that the latest version of software is
not installed or software in ECM is newer than software in MSD.
Disconnect and inspect these electrical connectors. Refer to Electrical Connectors Inspection (WP 0022 00):
ECM connector J1/P1 (WP 0053 00).