The rear lamp units are combined assemblies incorporating stop and tail lamps with flashing indicators and reflectors in a single unit on each side, the MGC using the same type as the MGB Mark II. The only significant change to the MGB rear lamp clusters was for the 1970 model year, when the lens profile changed from rounded to angular. The combined design means a failed bulb can affect multiple functions, for example a blown stop/tail bulb eliminating both the tail light and the brake light on that side, which is both an MOT failure and a safety hazard that should be rectified immediately.
Earthing & Common Faults
Chrome bumper rear lamp clusters rely on their physical fixing to the wings for their earth return, and corrosion at these contact points is the most common cause of unwanted circuit interactions such as stop lamps glowing when indicators operate, which is an earthing fault rather than a component fault and should be investigated first. Bulb holders can also corrode to the point where they no longer make reliable contact with the bulb base, and replacement holders are available individually.
When replacing lenses, new gaskets should always be fitted to maintain the water seal between the lens and the lamp body, as failed gaskets allow moisture into the assembly, causing rapid corrosion of the bulb holder contacts and the flickering or non-functioning rear lights common on older cars.
Reversing & Fog Lamps
Rear lamp assemblies are available for pre-1970 and post-1970 cars in home market and export specifications. Reversing lamp assemblies, lenses, and bulbs are available, mounted on the lower rear panel, with white lenses on most markets. A rear fog lamp is available for retrofitting and is a worthwhile addition for any car driven in winter, as the low profile and relatively dim original rear lighting can make these cars difficult for following traffic to see in heavy rain or fog. Number plate lamps changed several times on the MGB, overrider-mounted for pre-1974, D-shape black for post-1974, with chrome export variants, all available in the correct specifications.