1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 207Get this manual
Troubleshooting theDown"" Up" andTrailer" Circuits (All Circuits Inoperative) Connec Voltmeter red lead 10 Poin and black lead to Point 3, Ballery voltage should be indicated
No Voltege Indicated:
Battery Voltage Indicated :
Check battery leads lor poor connections or
open circuitsCheck battery chargeTeslluseon trim pump (If eQuipped)AelerlOMOlor and Electrica Tests", see IndexTest thermal overload switch
Connect Voltmeter red lead to Point 10Depress trailer bullan and Check lor battery volage
Battery Voltage Indicated:
Refer 10Motor and Electrical Tests", see Index,
Pump motor is faulty Reier toMotor Repair", see Index
No Voltage ndicated: Connect red Volt meter lead to POintand black lead to ground
No Voltage Indicated: