Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 83Get this manual
No voltage reading;
proceed to TEST 3
Battery Voltage
a, Disconnect BLACK ground wire(s) from Test Point 2bConnect voltmeter between common engine ground and Test Point 2cTum ignition key to "Start" position,
aReconnect BLACK ground wire(s)bConnect voltmeter between common engine grourn:l and Test Poinl3
12 Volt ReadingCheck BLACK ground wire lor poor connection or open CircuitReconnect ground wire starter solellOid; proceed TEST 70
cTurn ignition key to "Starr position,
No voltage reading; proceed TEST 0
12 Volt Reading
Defective starter solenoid
Electric Start Tiller Handle Model
Neutral start switch Is open or BLACK leads arB disconnected or damaged
No voltage reading; proceed to TEST 5
aConnect voltmeter between common engine ground and Test Point 4bTum ignition key to "Start" position
12 Volt Reading