Mercury – Malfunction Light Harness | 10-Foot Single-Helm Cable | 84-8M0048049

Overview

Catalyst-equipped MerCruiser engines need a clean, reliable way to connect their dash-mounted malfunction light to the engine’s diagnostic circuit. The Mercury 84-8M0048049 Malfunction Light Harness provides that link. At ten feet long, it’s sized for typical single-helm layouts and delivers a direct connection so the catalyst warning light can illuminate whenever the engine’s OBDM system detects an issue.

Key Features

• 10-Foot Harness – Built for single-helm installations requiring a clean run to the dash light.
• OBDM Connection – Carries the catalyst malfunction signal from the engine to the dash-mounted indicator.
• Catalyst-Engine Compatible – Designed for all MerCruiser engines equipped with a catalyst system.
• OEM Connector Fit – Factory plugs ensure proper pin alignment and secure engagement.
• Clean Routing Path – Flexible jacket makes it easy to run through rigging tunnels or behind panels.
• Reliable Signal Delivery – Allows the malfunction light to trigger accurately when service is needed.

Compatibility

• All MerCruiser catalyst-equipped engines
• Dash-mounted catalyst malfunction light (8M0046481)
• Single-helm harness routing setups

Performance & Practical Benefits

This harness keeps the catalyst malfunction light tied directly into the engine’s diagnostic system. The ten-foot length gives you enough room to route it cleanly from the engine compartment to the helm without stretching or forcing tight bends. Once installed, it ensures the dash light responds immediately when the catalyst system logs a fault—similar to the check-engine light on a car—helping you address issues sooner and avoid bigger problems later.

Why Buy OEM

Catalyst warnings are tied to emissions and engine protection systems, so the wiring needs to be accurate and dependable. Mercury’s OEM harness matches the engine’s electrical logic exactly, preventing false alerts or silent failures that can happen with off-brand wiring. The connectors fit tightly, the shielding holds up, and the harness is built to survive heat, moisture, and vibration in the engine room.

FAQ

Q1: What does this harness connect?
It links the engine’s OBDM catalyst alert circuit to the dash-mounted malfunction light.

Q2: Is it only for single-helm boats?
Yes. The 10-foot length is designed specifically for single-helm routing.

Q3: Will it work on any MerCruiser engine?
It works on any catalyst-equipped MerCruiser engine.

Q4: Does this harness include the malfunction light?
No. The light is sold separately (part number 8M0046481).

Q5: Is installation straightforward?
Yes. It uses OEM connectors and routes like any standard helm harness.