When rebuilding or overhauling a vehicle, many people choose to reinstall the old wiring harness, there maybe a number of reasons for this, but it is worth noting that old wiring once flexed and moved whilst being removed from the vehicle is more likely to fail than if left in situ. Cables, particularly in the area of the engine compartment harden over time, the insulation failing and causing short circuits.

Terminals including the Spade type become loose and corroded or contaminated with oil, this all causes voltage drop and potentially a heat build up with poor contacts at these connection points.

A replacement harness will pay dividends in the long run; it is worth noting that the individual sections are available separately on the Defender, i.e. Engine, Chassis and Main (Dash and Forward), Series harnesses are available as a complete set.

Autosparks harnesses are manufactured to the same British Standard Colour coding and cable size system as used by Land Rover, and we can usually help with a wiring diagram to assist with fitment if required.

Fitting a wiring harness may be a daunting prospect for many people, but this shouldn’t be, it is just a case of being methodical, take photographs for reference, and we sometimes advise to remove the old wiring loom leaving the last 3” of cables still attached, this way as the new loom is installed, you are able to quickly see what colour cable is fitted to what point.

Once you have installed your harness and you are ready to test, please use this next piece of advice before connecting the battery for the first time. Not all circuits are fused so it is a good idea to make sure everything is switched off on the vehicle, and then connect the battery indirectly through an inline fuse holder with, say, a 10 Amp fuse installed, this way you can test each circuit individually, knowing that if something isn’t quite right, the wiring is protected. This is a very satisfying process.