Mercury MerCruiser MCM 454 Mag MPI Service Manual page 648

SERVICE MANUAL NUMBER 23
TEST DESCRIPTION:
Number(s) below refer to the Step number(s) on the Diagnostic Table:
1. The MIL should be "ON" steady with the ignition "ON," engine "OFF." If not, chart A-1
2. Checks the serial data circuit and ensures that the ECM is able to transmit serial data.
3. If the engine will not start, chart A-3 should be used to diagnose the condition.
5. A scan tool parameter which is not within the typical range may help to isolate the area
Index
90-861326--1 MARCH 1999
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should be used to isolate the malfunction.
which is causing the problem.
GENERAL SYSTEM DIAGNOSTICS
Page 5E-55