Mercury Key Switch + 8-Pin Harness Wiring
- Mike Hill
- Sep 15, 2024
- 2 min read
Updated: Mar 26
When it comes to wiring a boat harness for your 1976 to 2005 Mercury outboard, each wire color serves a specific function that is crucial for the proper operation of your equipment.
Key Switch 6 Wires
RED Wire is connected to the battery, supplying a 12V+ power source to the system.
PURPLE Wire is your key switch turned-on power, providing a 12V+ power supply to various components such as fuel pump and dash lights.
BLACK Wire is the ground wire, ensuring a proper ground from the battery to the engine block to the key for operation.
YELLOW/BLACK Wire is dedicated to the primer "choke" solenoid, which provides fuel to help cold starting the engine..
YELLOW/RED wire hooks to your starter solenoid to engage the starter, allowing you to start the engine.
GRAY Wire serves as the tach lead, providing information on the engine's RPMs (revolutions per minute).
BLACK/YELLOW Wire is your kill switch, turns the motor off and enables the lanyard to stops the engine in case of an emergency.
8-Pin Harness 2 Additional Wires
TAN/BLUE wire is linked to the temperature gauge, monitoring the temperature of the equipment to prevent overheating.
TAN Wire is connected to the warning horn, alerting you to any potential overheating issues that may require you shut the motor off immediately.
Trim Wires
BLUE Wire(s) is designated for the trim up function, allowing you to adjust the trim of your equipment for optimal performance.
GREEN Wire(s) controls the trim down feature, providing you with control over the downward adjustment of the trim.
Understanding the purpose of each wire color is essential for rigging, troubleshooting and maintenance.
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