Classic Car Electrical Wiring

Classic vehicle wiring

Classic and vintage vehicle autoelectrical systems often feature more basic automotive wiring systems.
Vintage british vehicle wiring sometimes connects the battery directly to bakelite switch to component, with occasional ignition and auxilliary circuits protected by fuses. Relays and Solenoids may be fitted to provide remote switching.

A typical classic vehicle wiring circuit may use copper cored wiring with a solid colour insulation on cables to supply power to a switch.
Live from the switch to the component may be wired using cable with a solid + tracer colour insulation.

British Rootes Vehicles : Positive Earth Wiring System : Typical Wiring Colours & Circuit Function

Some information interpreted from an old car wiring diagram dating 1940's. Different vehicle wiring diagrams vary !

to brush Fuel levelIgnition Coil to Contact Breaker CB (Points)Stop lamp switch, Fuel guage power, Sreen Wiper switch power
Wire No.Wire ColourFunctionComponent
1RedSidelamps, tail lights, Boot light, Panel lights rheostatLighting circuit
2Red & Yellow
3Red & Blue
4Red & White
5Red & Green
6Red & Brown
7Red & BlackDipper Solenoid Switch
8YellowD Dynamo
9Yellow & Blue
10Yellow & Green
11Yellow & Brown
12Yellow & Purple
13Yellow & BlackBattery Negative to Ammeter to Cigar Lighter fuse
14BlueLights H at Light SwitchHeadlights
15Blue & White
16Blue & GreenCigar lighter fuse to cigar lighter & switch
17Blue & Brown
18Blue & PurplePetrol gauge to tank unit
19Blue & Black
20WhiteIgnitionA3 Voltage Regulator, Ignition to Coil SW, Ignitio to push switch solenoid
21White & Green
22White & Brown
23White & PurpleF Dynamo to Ammeter A
24White & BlackA1 at Current Voltage Regulator, A at Light Switch
25GreenIndicators Trafficator
26Green & Brown
27Green & PurpleScreen Wiper Switch to Motor
28Green & BlackScreen wiper switch
30Brown & Purple
31PurpleHornPower to Horn
32Purple & BlackBrake lights, Fuel level
33BlackChassis Ground to Battery Negative

Wiring faults can arise due to component age and deterioration. Replacement parts may be obsolete and hard to source. Old car wiring systems may lack adequate circuit protection so fitting of additional fuses is often recommended.

Classic vehicle electrical system voltage

Older Classic and vintage car and tractor electrical systems may feature different system voltage to modern vehicles including 6 volt starting and charging. 6 Volt car electrical equipment can be difficult to source. It may be possible to rebuild 6 volt starter motors and dynamos subject to component availability.

Magneto Ignition Systems

Magneto ignition systems are found on earlier petrol classic motor cars and petrol classic tractors such as the early Fordson tractors.

Distributor and Contact Breaker Points Ignition Systems

Distributor ignition systems found on classic vehicle petrol engines feature a two stage ignition coil with primary low tension circuit switched by contact breaker points set to correct air gap. Dwell angle refers to when contact breaker points are closed. A secondary high tension circuit is connected to distributor cap centre terminal. A rotating arm (rotor arm) switches high voltage power between distributor cap king lead terminal and cylinder lead terminals in engine firing order. High tension HT leads carry the ignition spark to spark plugs located in each engine cylinder.


Vintage vehicles may be fitted with a 'Dynastart' unit which combines an electric starter and generator. A v-belt is often used running directly on the flywheel periphery or on crankshaft pulley. Some versons may use chain drive. Dynastart units may be of four pole design with two poles carrying series windings for starting, and two shunt windings for power generation similar to a conventional dynamo. If a dynastarter fails to operate check battery cell condition and electrolyte level, battery voltage and terminal connections, check for slipping belt, jammed or broken drive mechanism.


2 Brush Dynamo
3 Brush Dynamo on earlier vintage vehicles Dynamo charging systems which may be three brush type on earlier vintage vehicles or later two brush types. External control box voltage regulator often mounted in engine bay or bulkhead controls dynamo charging output .

HT Ignition System

Classic and vintage vehicle ignition systems may include
HT ignition coil,
Ignition distributor with mechanical or vacuum ignition advance and retard adjustment.


Classic vehicles may feature Non Standard lighting systems which may be acceptable due to date of manufacture or Mot exempt due to age.

Blast Cleaning

We have Sandblasting and Sodablasting machines for restoration cleaning of classic vehicle parts

Specialist Auto electrical fault finding

Mobile vehicle diagnostics service and repair to vehicle wiring, electronic and mechanical systems including Car Van and Truck diagnostics:


Classic vehicle battery systems may be :
Positive Earth on earlier models.
Negative Earth on later models.
Insulated return wiring system on some commercial vehicles such as ERF.

battery isolator switches

Battery Isolator Switches

We often advise fitment of a battery isolator switch to classic vehicles due to the age of components and to protect the vehicle when not in use.

manufactured battery lead

Battery Leads

Battery leads should be checked for insulation damage caused by chaffing, or oil, fuel and water leaks. Replace damaged or corroded battery leads.

battery terminal

Battery Terminals and Covers

Battery terminals should be kept clean and tight, light greasing with petroleum jelly may help prevent corrosion. Deteriorated battery terminals should be renewed.


Dynamos for Classic Cars

Dynamo charging systems may be three brush type on early vintage vehicles with output control by third brush position. Later dynamos are often two brush type.


Dynamo Voltage Regulator Control Boxes

We can supply brand new dynamo control voltage regulators for classic cars which are copy parts, we have some original equipment secondhand Lucas CAV control boxes in stock where originality is required.




connector block

Block Wiring Connectors
for Classic and Vintage Cars

The original classic vehicle Lucas type bullet wiring connector blocks are often prone to corrosion and a source of wiring faults.
Replacement connector blocks and solder type or solderless crimp terminals are readily available.

workshop assortment boxes

Boxes of Workshop Assortments
for Car Restoration Garages and Repairers

wiring terminals

Cable Terminals and Wiring Connectors

lucar wiring terminals

Lucar Terminals

7 core cable

Cables and Wires

Classic car wiring cables may need replacement due to age, breakdown of insulation, and deterioration of copper core cables. Some older vehicles use copper cored cable with woven insulation which may be sourced by special order.

cable sleeving
Cable Sleeving
Split Conduit tube
Spiral wrap
insulation tape

Insulation Tapes, Adhesives and Velcro


Cable Ties and Cable Clips

wiring grommets
Cable Grommets

Use cable grommets to protect cabling against chaffing of insulation where the cable passes through holes in sheet metal bodywork

megafuse holder

Fuse Boxes and Holders


Early pre 1970 classic vehicles may be fitted with glass fuses, often with one or two 35A or 50A fuses covering multiple circuits.
1970's vehicles were fitted with additional fuses for seperate circuits rated to circuit loading.
1980s vehicles were often fitted with standard ATO blade fuses.

plugs sockets
Plugs and Sockets

Lucas ACR & A127 type plugs for connection of alternator wiring. /td>

Flasher Relays, Normally Open, Normally Closed Relays

Please check the polarity of the vehicle wiring system present if ordering Flasher relays as many are only suitable for Negative Earth vehicles. Relays should be used when fitting additional electrical loads such as spot or driving lamps.

toggle switch


Classic vehicles may use bakelite switches as original equipment. Bakelite type switches may sometimes be carefully dismantled and contacts cleaned then reassembled where replacements are not available.

fuel hoses

Hoses, Tubes and Filters

Multi fuel hose for automotive use ,Heater hose,Brake bleeder tube,Windscreen washer tubing

jubilee hose clips

Hose Clips and Hose Menders

Coolant hose clips and pipe hosetail joiners for use on vehicle cooling systems


Battery Cable

Manufactured Battery Leads

Single Core Cable

Multi Core Cable

Diesel Fuel Injection Equipment Fuel hose
Diesel Glow Plugs and Preheat timer Relays

Electric Doors and Access Steps


Ignition Leads Coils Modules

Jump Lead Clips

Lighting and Marking
Reflective Rear Marking and Marker Plates

Marine Bilge Pumps

Engine Sensors and Switches
Air Mass Flow Meters
Fuel injection
Camshaft and Crankshaft Timing

Panel Lamps

Power Supplies Step Down droppers

Relays & Flasher Units


Welding Cable

Windscreen Wiper Motors

Windscreen Washer Kits

Wiring Tools