Mercury – Malfunction Light Harness | 20-Foot Single-Helm Cable | 84-8M0048055

Overview

Catalyst-equipped MerCruiser engines rely on a clear dash-mounted indicator to alert you when the catalyst system needs attention. The Mercury 84-8M0048055 Malfunction Light Harness gives you a 20-foot run—ideal for single-helm boats with longer distances between the engine compartment and the dash. Once connected, it provides a clean, reliable path for the OBDM catalyst warning signal so the light can turn on the moment a fault is detected.

Key Features

• 20-Foot Harness – Extra length for single-helm boats with deep or extended routing paths.
• OBDM Alert Connection – Carries catalyst malfunction signals directly to the dash-mounted indicator.
• Catalyst-Compatible – Fits all MerCruiser engines equipped with a catalyst system.
• OEM Connectors – Factory Mercury ends ensure a proper fit and a secure, vibration-resistant connection.
• Flexible Routing – Long enough to run through rigging tunnels, bulkheads, and tight console spaces.
• Accurate Warning Delivery – Ensures the malfunction light activates promptly when service is needed.

Compatibility

• All MerCruiser catalyst-equipped engines
• Dash-mounted Catalyst Malfunction Light (8M0046481)
• Single-helm installations requiring a 20-foot harness

Performance & Practical Benefits

This harness provides the length needed for clean, stress-free routing on larger or more complex helm layouts. Once in place, the malfunction light becomes a dependable visual cue—similar to a check-engine light—alerting you quickly to catalyst faults. It helps you stay ahead of emissions-system issues without adding additional displays or wiring complexity.

Why Buy OEM

Catalyst alerts are tied to essential engine protection routines. Mercury’s OEM harness ensures the signal is carried correctly and the warning light behaves exactly as intended. Aftermarket harnesses often suffer from poor pin alignment or weak shielding, leading to unreliable alerts. The OEM version offers the durability and electrical accuracy needed in a marine environment.

FAQ

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

Q2: Why choose the 20-foot version?
It’s ideal for single-helm boats that need extra length to reach the dash cleanly.

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

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

Q5: Is installation straightforward?
Yes. It installs with OEM connectors and routes like any standard dash harness.