Stop unwanted indicator cross-flashing when upgrading to LED bulbs with the plugpal LED Indicator Diode Harness. Designed for classic cars and motorcycles with negative earth wiring systems, this harness provides a simple and reliable fix for the common LED conversion issue known as sympathy flash.

What Causes “Sympathy Flash”?

On many classic vehicles fitted with a single dashboard indicator warning (tell-tale) light, converting to LED indicator bulbs can cause both left and right indicators to flash together—similar to hazard lights.

Because LED bulbs draw very little current, electricity can backfeed through the dashboard warning lamp into the opposite indicator circuit.

If your indicators operate normally when you remove the dash warning bulb, this diode harness is the correct and permanent solution.

How the plugpal Diode Harness Solves the Problem

Using high-quality automotive diodes, this harness:

• Prevents reverse current flow between indicator circuits
• Eliminates LED cross-flashing issues
• Restores correct left and right indicator operation
• Maintains proper dashboard tell-tale function

A fast, professional fix for classic LED indicator conversions.

Product Features

• Suitable for negative earth vehicles only
• Universal fit for classic cars and motorcycles
• Durable ABS enclosure
• PET braided cable sleeve for added protection
• Adhesive-lined heat shrink for improved moisture resistance
• Crimps supplied for wiring re-termination if required
• Built using quality automotive-grade components

Simple Installation

• Two leads connect to the existing wires feeding the dashboard tell-tale bulb
• Single output wire connects to the bulb
• Supplied earth lead grounds the bulb correctly

In some installations, cutting and re-terminating existing wiring may be required — crimps are included to make this straightforward.

As a universal product, wiring colours in your vehicle may differ from those shown in installation instructions.

The Essential Upgrade for Classic LED Indicator Conversions

If you’re experiencing LED indicator cross-flashing in your classic car or motorcycle, the plugpal LED Indicator Diode Harness provides a dependable, easy-to-install solution.

Restore proper indicator function and complete your LED upgrade the right way.

Installation instructions are attached to the Product Documents section below this description in the auction listing.  This is a universal product so please be aware that the wiring colours on your existing loom will be different to those shown in the instructions.