Hazard flashers, the simultaneous flashing of all four indicators to warn other road users of a stationary or slow-moving vehicle, became standard equipment on UK cars from the mid-1970s, but most classic MGs built before that date left the factory without them. Retrofitting a hazard-flasher system to an earlier car is one of the most worthwhile safety upgrades available, particularly for cars used on modern roads where the ability to signal a breakdown clearly is genuinely valuable and increasingly expected by other road users. This section also covers the complementary headlamp relay kit, a related electrical improvement that addresses a fundamental weakness in the standard headlamp circuit.
Hazard Warning Kits
The hazard warning kit gathers the components needed for a complete installation, a dashboard-mounted illuminated switch with the standard hazard symbol, a dedicated flasher relay that takes power from the battery rather than the ignition switch so the hazards work with the ignition off, the standard requirement for a breakdown warning, and the wiring and connectors to feed all four indicator circuits simultaneously. Quality kits such as the Retronics unit use a microprocessor-based flasher that maintains a consistent flash rate regardless of how many bulbs are working or whether filament or LED bulbs are fitted, are dual-polarity to suit both positive and negative earth cars, and carry a multi-year guarantee. Installation requires routing the supply wire from the battery through the bulkhead with appropriate fusing, mounting the switch in an accessible dashboard position, and tapping the connections into the existing indicator wiring at the front and rear of the car, the result being a fully-functional hazard system that operates independently of the normal indicator flasher relay. On most of the range the system is a retrofit to cars that never had it, while on the few applications that did leave the factory with hazards the kit serves as a renewal where the original switch, relay, or wiring has failed.
LED Compatibility
For cars fitted with LED indicator bulbs, an electronic flasher relay is required rather than the thermal flasher used with conventional tungsten bulbs, as a standard unit will not flash correctly with the reduced current draw of all four LED bulbs operating simultaneously, flashing too fast or not at all. The microprocessor-based hazard units handle both filament and LED bulbs correctly at the proper flash rate, so where LEDs are fitted or planned the LED-compatible relay should be specified.
Headlamp Relay Kits
The headlamp relay kit addresses a fundamental weakness in the standard headlamp circuit, where the full current draw of both headlamps passes through the headlight switch contacts, causing them over time to pit and corrode and produce the flickering at idle that is a common complaint. The relay kit routes the supply directly from the battery through dedicated relays, with the switch operating only the relay coil, the result being brighter headlamps from the reduced voltage drop, elimination of the idling flicker, and significantly longer switch life. Pre-wired with plug-in connectors for straightforward installation and suiting both positive and negative earth cars, the headlamp relay kit is a natural companion to the hazard installation, both being practical electrical upgrades that make a genuine difference to safety and reliability on any classic MG used regularly. The technical team is available to advise on the right specification for a specific car and existing electrical configuration.