The indicator and sidelamp specification changed at several points and differs between home market and export cars, the MGC using the same type as the contemporary MGB Mark II. Chrome bumper cars generally had combined side and indicator lamps below the headlamps in the front wing, with the lens typically white and amber for home market cars, and rear indicators integrated into the combined rear lamp assemblies. The lamp units were moved slightly closer to the radiator grille on 1969 models, and on rubber bumper cars new front indicator lamps were fitted in the bumper.
Components
Front lamp assemblies, backplates, chrome bezels, lenses in all specifications, gaskets, lens screws, wiring connections, and the rubber bumper indicator assembly are all available individually for targeted replacement. When refitting lenses after cleaning or bulb replacement, the gasket must be correctly seated to maintain the water seal, as a leaking gasket allows moisture into the lamp body, corroding the bulb holder contacts and causing intermittent flashing or failure, one of the most common minor electrical faults on older cars.
Flasher Unit & Diagnosis
A critical diagnostic point on the MGB is that when indicators fail, the hazard warning switch should always be checked first, as the indicator circuit runs through it and a failing switch disables the indicators entirely. The flasher unit controlling the indicator rate is a thermal type mounted behind the dashboard, working by heating a bimetallic strip that makes and breaks the circuit at a regular rate, and a failed unit causes either no flashing at all or an incorrect flash rate. The flash rate also changes if the wrong wattage bulb is fitted, a higher wattage bulb causing faster operation while a failed bulb on one side causes the remaining indicators to flash more slowly, which is a useful diagnostic, as faster than normal flashing on one side usually indicates a blown bulb on that side. Side marker lamps in amber front and red rear were fitted to export cars from 1968, with plinths, lenses, and gaskets available for all positions.