Sierra Voltage Regulator 18-5743-1, Replaces 815279A2 815279-1, Fits Mercury 16/40 Amp Charging Systems 1989-91

The Sierra 18-5743-1 voltage regulator is a direct-fit electrical component for Mercury outboard engines equipped with a 16 amp or 40 amp charging system, model years 1989-91. It regulates the output of the engine's charging system, protecting the battery and onboard electronics from overcharging while maintaining stable voltage output during operation. The unit is wired with a black, yellow, red, red, yellow, and gray wire set; the black wire connects to engine ground.

This regulator is a straightforward replacement for the original Mercury charging system regulator on covered engines, restoring proper charging function without modifying existing wiring. It is built to the same fit and connection points as the original equipment part it replaces.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-5743-1
• Product Type: Voltage Regulator
• UPC: 808282392321
• Weight: 0.63 pounds
• Wire Colors: Black, Yellow, Red, Red, Yellow, Gray
• Ground Wire: Black wire connects to engine ground
• Charging System Compatibility: 16 amp or 40 amp

Fitment

• Mercury engines with 16 amp or 40 amp charging system, model/years 1989-91

Replaces (OEM)

• 815279A2
• 815279-1

Frequently Asked Questions

What does the Sierra 18-5743-1 voltage regulator fit? This regulator fits Mercury engines equipped with a 16 amp or 40 amp charging system, model/years 1989-91.

What OEM part numbers does this regulator replace? The 18-5743-1 replaces Mercury OEM part numbers 815279A2 and 815279-1.

How much does the voltage regulator weigh? The Sierra 18-5743-1 weighs 0.63 pounds.

What color wires does the 18-5743-1 have? It comes with black, yellow, red, red, yellow, and gray wires.

Where does the black wire connect? The black wire on the 18-5743-1 goes to engine ground.

Will this regulator work with a 40 amp charging system? Yes, the 18-5743-1 is designed for Mercury engines with either a 16 amp or a 40 amp charging system.

Is the Sierra 18-5743-1 a direct replacement for the original Mercury regulator? Yes, it is a direct replacement for Mercury regulators 815279A2 and 815279-1 on covered engines.

Does the 18-5743-1 fit engines from 1992 or later? No, this specific part number, the 18-5743-1, is designated for model/years 1989-91.

What is the UPC for this part? The Sierra 18-5743-1 voltage regulator has UPC 808282392321.

What type of engine charging system does this regulate? The 18-5743-1 regulates output on Mercury outboard engines with 16 amp or 40 amp charging systems.