80 Series Land Cruiser Headlight Wiring

The following information is applicable to the negatively switched headlight wiring assemblies of Australian and USA 80 series LandCruisers.
Many thanks to Ian Bragg for the words and diagrams.

As most people will soon be aware of when they purchase their 80 Series Land Cruiser, the standard wiring for the headlights leaves something to be desired. It will not support high output headlight globes (blows fuses) and the standard wiring often has high losses of voltage even on the standard 60/55 (H4) globes.

The obvious answer is to either buy (expensive) or make your own headlight harness that supplements part of the existing wiring. Now, due to the negative switching of the Toyota wiring this can be quite confusing the first time you look at it. In addition, it isn't hard to lose the good parts of the original design like the auto-off feature.

Following, is a workable solution to upgrading your lights wiring. The added wiring uses the left hand side headlight connector for connections into the existing wiring. It does NOT cut into or permanently disable the factory wiring. If the new wiring were to fail, all that is involved is to dissconect the wires that are hoodek into one of the factory headlights connectors and reconnect the factory wiring to each headlight assembly. In this modification, we add wiring which is controlled by the factory supplied wiring arrangement.

The added wiring uses the left hand side headlight connector for connections into the existing wiring. Each relay has its own power cable feed straight from the battery. Total cost of parts was about $80 Australian plus cable. The cable sizes used were12G (6mm) to supply power to each relay and ground each headlight globe, and 14G (4mm) to supply power to each globe from the relay. The rest used 16G (3mm) wiring for durability. Headlight connectors used were ones that had flyleads on them. I soldered these to the wiring and then put heat-shrink over the join. Make sure the connectors you get have flyleads of at least 14G (4mm) and are of decent quality.
NB: Not all items are required for USA models.

If you have a query or can see a mistake here, please email me at Ian.Bragg@earthling.net .

Aus Spec Diagrams
US Spec Diagrams
Original Wiring
Modified Wiring
Original Wiring
Modified Wiring

NB: The following.
This represents a standard automotive type relay. It has two outputs (marked 87). I've used one output for the left hand side and the other for the right hand side (86 is the relay switch input). 
This resistor is installed as a current limiting safety measure. The circuit will work without it, but it limits potential current through stalk switch assembly. I have measured momentary current flow in excess of 7 amps without the resistor. The resistor has no (would you believe very, very little) impact on the high beam indicator light brightness. The value is not overly critical, and I chose to use a 27W 5W resistor for robustness. 
This is an inline fuse assembly with a fuse that blows at the value indicated. 
This, for me, was the magic in solving this circuit without hacking into the existing wiring at all. If this diode is excluded, and high beam is selected when you switch the motor off and leave the vehicle (without turning the lights off at the switch), then low beam will switch on, and consequently flatten the battery. The model of diode is not critical (NOT zener), it just needs to be robust with good solid leads.
This indicates the added wiring and hardware.