Sierra Johnson Evinrude Ballast Resistor 1.5 Ohm, Part 18-99377

The Sierra 18-99377 is a 1.5 Ohm ballast resistor built for Johnson Evinrude outboard ignition electrical systems. A ballast resistor regulates the voltage supplied to the ignition coil, protecting the coil and points from excess current during normal running conditions and helping maintain a stable, consistent spark. This is a straightforward electrical component intended as a direct replacement when an existing ballast resistor has failed or is reading outside its rated resistance value, which is a common cause of hard starting, misfiring, or intermittent ignition trouble on affected Johnson Evinrude outboards.

Installation is a simple electrical swap: the resistor mounts in the ignition circuit between the power source and the coil, with wire leads for connection into the existing harness. Because ignition timing and coil performance depend on the resistor holding its rated value, replacing a degraded unit with a correctly rated 1.5 Ohm resistor like the 18-99377 helps restore reliable starting and running performance. The part is sold under the Sierra brand and is intended for use within the Johnson Evinrude outboard electrical system.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99377
• Resistance: 1.5 Ohm
• Application: Johnson Evinrude outboard electrical system
• UPC: 808282399290
• Weight: 0.2 pounds

Fitment

Designed for Johnson Evinrude outboard ignition electrical systems.

Frequently Asked Questions

What is the resistance value of the Sierra 18-99377 ballast resistor? The Sierra 18-99377 is rated at 1.5 Ohm.

What does a ballast resistor do in an outboard ignition system? It regulates the voltage delivered to the ignition coil, protecting the coil and points from excess current and helping maintain a stable spark, which is the function of the Sierra 18-99377 ballast resistor.

What outboards is the 18-99377 ballast resistor designed for? The Sierra 18-99377 is designed for use in the Johnson Evinrude outboard electrical system.

How much does the 18-99377 ballast resistor weigh? It weighs 0.2 pounds.

What symptoms indicate a ballast resistor needs replacing? Hard starting, misfiring, or intermittent ignition trouble on a Johnson Evinrude outboard can point to a failed ballast resistor, which is what the Sierra 18-99377 is intended to replace.

Is the Sierra 18-99377 a direct replacement part? Yes, the 18-99377 is a 1.5 Ohm ballast resistor intended as a replacement in the Johnson Evinrude outboard ignition circuit.

Where does the ballast resistor mount in the ignition circuit? The 18-99377 ballast resistor connects in the ignition circuit between the power source and the coil, wired into the existing harness.

What is included when ordering the 18-99377? Ordering the Sierra 18-99377 gets you one Johnson Evinrude ballast resistor rated at 1.5 Ohm.

Is the Sierra 18-99377 an electrical or mechanical part? It is an electrical component, a ballast resistor, used within the ignition circuit of the Johnson Evinrude outboard electrical system.

Why does the resistance rating matter when replacing this part? Ignition coil performance depends on the resistor holding its rated value, so a replacement must match the 1.5 Ohm rating of the Sierra 18-99377 to maintain correct ignition operation.