Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 100Get this manual
CHARGINGSTARTING SYSTEM
aConnect voltmeter between common engine and Test Point1bTurn ignition key to "Start" position
No voltage reading: Defective starter solenoid
12 Volt Reading
Should hear solenoid click: proceed to TEST 8
aReconnect BLACK cable (with YELLOW sleeve) to starter solenoid Test Point 1bConnect voltmeter between common engine ground and Test Point 7cTurn ignition key to "Start" position
No voltage reading: Check BLACK cable (with YELLOW sleeve) for poor connection or open circuit
12 Volt Reading