Mercury – Malfunction Light Harness | 30-Foot Single-Helm Cable | 84-8M0048057

Overview

Catalyst-equipped MerCruiser engines rely on a clear and dependable warning light to let you know when the emissions system needs attention. The Mercury 84-8M0048057 Malfunction Light Harness provides a full 30 feet of length—ideal for single-helm boats with long console runs, deep rigging paths, or layouts where shorter harnesses simply won’t reach. Once installed, it gives your dash-mounted catalyst light a clean, reliable connection to the engine’s OBDM alert circuit.

Key Features

• 30-Foot Harness – Longest single-helm option for extended console and rigging layouts.
• OBDM Signal Path – Carries catalyst malfunction alerts directly to the dash indicator light.
• Catalyst-Engine Compatible – Works with all MerCruiser engines equipped with a catalyst system.
• OEM Connectors – Factory Mercury ends ensure proper pin alignment and a secure fit.
• Flexible Routing – Length designed for boats with complex wiring paths or larger hulls.
• Reliable Warning Delivery – Ensures the malfunction light turns on immediately when a fault is detected.

Compatibility

• All catalyst-equipped MerCruiser engines
• Dash-Mounted Catalyst Malfunction Light (8M0046481)
• Single-helm installations requiring a 30-foot harness

Performance & Practical Benefits

This harness gives you enough reach to route the malfunction-light connection cleanly from the engine compartment to the helm—even on large cruisers or deep-V hulls. Once connected, the warning light becomes a dependable early indicator—much like a check-engine light—alerting you the moment the catalyst system needs attention. It’s a simple, essential link that helps prevent minor issues from becoming bigger, more costly problems.

Why Buy OEM

Catalyst fault alerts must reach the dash accurately, and OEM harnessing ensures the signal stays clean. Mercury’s factory connectors, proper shielding, and correct wiring logic eliminate the guesswork and reduce the risk of false alarms or silent failures—issues that often show up with aftermarket cables. With an OEM harness, you’re getting consistent, reliable performance built for harsh marine environments.

FAQ

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

Q2: Why choose the 30-foot version?
It’s the right choice for single-helm boats with long or complicated rigging routes where shorter harnesses won’t reach.

Q3: Will this work on all MerCruiser engines?
It works on any MerCruiser engine equipped with a catalyst.

Q4: Is the warning light included?
No. The light is sold separately (part number 8M0046481).

Q5: Is installation difficult?
Installation is straightforward—plug in the connectors and route the harness through standard rigging channels.