Recalling that the VW Type 2’s wiring colours were based upon the German DIN standard, and that Germans tend to predominantly favour German-built cars, it might be fruitful to investigate suppliers of automotive electrical cable in Germany; perhaps starting with German E-bay.
https://www.ebay.de/b/Kabel-Kabelbaume-fur-die-Elektrik-im-Auto/179675/bn_886835
Until auto-electrical suppliers such as Merv Plastics (later renamed Vehicle Wiring Products), started making mail-order catalogues available in pre-Internet days, there were few if any easily-identifiable sources of colour-coded electrical cables in appropriate current ratings; especially multi-coloured cables with a dominant base colour and one or more tracer colours. In those days, to the best of my knowledge, my only available recourse, was to visit the local car breakers’ yards and salvage complete or partial wiring looms for the 1974 Triumph Toledo and 1973 VW Type 2 projects.
The cables used in sections of wiring-loom sections behind the dashboard and in the engine compartment, commonly have short runs, so unless one only needs short sections of multi-coloured cable, it is usually preferable to salvage the wiring loom sections with long uninterrupted runs of cable, which run from the front of the passenger compartment to the rearmost extent of the vehicle.
This is what I did for a few of my projects, especially that on the 1973 VW Type 2, which warranted a much more extensive custom, replacement wiring loom (about six times more extensive than the original factory-fitted wiring loom), to facilitate the retro-fitment of a comprehensive instrumentation system for the rear-mounted engine, plus several supplementary lamps, booster fans and other electrical accessories.
To obtain electrical cable of the wiring colours and current-ratings I wanted, I salvaged several partial wiring looms, from a variety of vehicle marques; including BLMC (typically Triumph Dolomite / Toledo and Austin Metro / Maestro / Montego), Vauxhall (typically Astra & Cavalier), Volvo and Honda, plus probably I few I cannot recall. Given that the VW Type 2’s wiring colours were based upon the German DIN standard, it was particularly useful to source cables from British, Japanese & pre-1989 Eastern-European vehicles, whose wiring colours were based upon other national standards.
The 1973 VW Type 2’s original factory-fitted wiring loom, included very few cables of green or blue as the dominant base colour with various tracer colours, apart from blue / red for the courtesy light (the system of colour-coding indicated that red / blue would have been more appropriate, so I changed it!), blue / white for the headlamp main-beam warning light, and a very-short length of green for the ignition distributor condenser (i.e. capacitor). VDO Cockpit accessory gauges or optional wiring kits, were commonly supplied with green cable. Hence, I chose a selection of blue / tracer-colours for the supplementary warning & tell-tale lights and green / tracer-colours for the gauges; creating my own non-standard sub-system of wiring colours which I documented in my vehicle-diary and supplementary electrical-circuit wiring diagrams.
Although many auto-electrical suppliers such as Vehicle Wiring Products, Auto Electric Supplies, Auto Electrical Spares, 12 Volt Planet and Polevolt etc, now have Internet websites, it is still difficult to source some multi-coloured cables with a dominant base colour and one or more tracer colours. I imagine that cables such these are still manufactured for vehicle manufacturers, for use in current production cars, but the challenge is to identify these suppliers and persuade them to supply small quantities to private individuals.
www.carbuildersolutions.com
https://www.vehiclewiringproducts.co.uk
https://www.autoelectricsupplies.co.uk/
https://www.autoelectricalspares.co.uk
www.12voltplanet.co.uk
http://polevolt.co.uk/
