Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 125Get this manual
WIRING DIAGRAMS
Water Temperature Gauge
WIRING DIAGRAM A
Use this wiring diagram when using separate light switch for instrument lighting
aConnect to12 Volt+12 Volt Light Switch WirePosition Light Bulb to the Switched PositionConnect to NEGATIVE () GroundConnect to TAN Lead located at the Tachometer Receptacle on Commander Side Mount Remote Control or TAN Lead coming from Accessory Ignition Choke Assembly
WIRING DIAGRAM B
Use this wiring diagram when instrument lighting is wired directly to the ignition key switch(Instrument lights are on when ignition key is turned on