I have been asked to show how to fit reverse lights to a Series Land Rover, such that they illuminate automatically, not needing the driver to operate any switches.
Provision was made for this on all later SIIIs, with suffix D and later gear boxes, but it is a simple job to fit a similar system to earlier units.
If you look at the mounting bracket for the gear stick pivot ball, you may see a drilled hole on the rear face, towards the right hand side. This is for the reverse light switch. It is a spring loaded plunger switch, very similar to the brake light switch, and is operated by the gear box’s reverse selector shaft inhibit flap (the spring loaded flap that prevents the driver from accidentally moving the gear stick into the reverse gate). On the rear edge of this flap is a small steel tab, angled downwards. This simply presses the switch when reverse is selected.
SIII suffix C and earlier boxes have a slightly different flap, without the tab, and may also lack the hole in the stick mounting. It’s a simple mod to sort those out, though, using a strip of folded steel for the tab, secured by the flap adjustment bolt and some JB Weld (an epoxy for metals) or a couple of tack welds. The switch hole is drilled in line with the newly added tab (with reverse selected).
The switch was unavailable when I carried out the mod on my 109, so I used a standard brake light switch for the dual circuit brake system, which required the enlargement of the hole. Using a nut on the shaft of the switch on each side of the gear stick mount, I can adjust the position of the switch to prevent it blocking reverse selection and set it to activate the light at the correct point.
The power is fed to the switch by a dedicated feed from the fuse box. Make sure you include a fuse in the circuit – the first time around, I didn’t and had the start of an electrical fire when the switch output wire contacted the exhaust and melted the insulation, causing an unrestricted short. Thankfully, since I was reversing, I was able to shut off the engine instantly and use the battery isolator switch to cut off all the electrics. It’s amazing how fast an electrical fire fills the interior with choking smoke, thick enough to prevent all vision.
The rear light can be of whatever choice you prefer. I initially used a single rectangular light as used on the very late SIII Countys and earlier Defenders, but recently upgraded to a pair of NAS circular lights. Some use sidelights meant for the front wings, which work fine as long as you don’t use them long – at 5W (sidelight bulb, too dim for reversing) the heat generated is fine, but at 21W (reverse light bulb), the heat starts melting the sprung plastic disc in the light unit that carries the positive bulb contact. The light is then just earthed to the body or chassis. Simple!