Cortina MK1 Electrical Wiring Specifications
Page still under construction
Page last edited:- July 10, 2005 15:17
The following colour codes are used on vehicles up to 1974.
Wiring Colour Abbreviation Wiring actual colours Electrical specification of cable Where the cable is used Comments BL Blue Light switch to headlamp dip switch BL/R Blue / Red Light switch to Dipped Headlamps BL/W Blue / White Light switch to Main Headlamps & Main beam indicator W White From ignition switch to accessories W/R White / Red Ignition switch to starter solenoid W/BR White / Brown Oil warning sender to oil warning lamp W/BK White / Black Distributor to contact CB on ignition coil W/ Y White / Yellow Coil + or SW connection G Green Ignition fuse to wiper motor, & Ignition fuse to instruments G/Y Green / Yellow Stoplight switch to Stoplights G/R Green/Red Left hand (Near Side) indicator feeds G/W Green/White Right hand (Off side) indicator feeds G/BL Green / Blue Temperature gauge to sender unit G/BL Green / Black Petrol gauge to tank sender unit G/BR Green/ Brown Reversing light switch to reversing lamps BR Brown Control Box A1 to ignition switch (on dynamo cars only) Main battery feed to Control Box, and equipment supplied directly from battery.
Also to ammeter if fitted.
Heavy cable BR/Y Brown / Yellow Dynamo to control box (D contact) and ignition warning light. BR/G Brown / Green Control box (F contact) to dynamo field coil. BR/W Brown / White Ammeter to Control box (dynamo cars) R Red Rear Lights and number plate lamp & Light switch to panel light switch Y Yellow R/W Red / White Feeds to instrument panel lamps R/BR Red / Brown BK Black Coil -ve or CB connection & distributor connection.
Also used as Earth wire.
BK/GR Black / Green Wiper switch to wound field wiper motor. Permanent magnet motors may use blue/green, red/green or brown/green GR/.R Light Green / Red Left indicator GR / BL Light Green / Blue GR / P Light Green/ Purple Direction indicator warning lamps to Flasher Unit GR / BR Light Green/ Brown Flasher unit to direction indicator switch GR / W Light Green / White Right Indicator P/Y Purple / Yellow Horn relay to horn P/BK Purple / Black Horn push to horn P/W Purple / White Interior lamp to door switch
Notes on Wires.
1) As far as I know, the Cortina wiring loom conforms to the "Lucas Colour Code" scheme. (Is this the same as BS-AU7a 1983 Colour Code for Vehicle Wiring(??)
2) The first colour stated is the main colour of the insulation. The second colour is the "stripe" or tracer colour which twists along the length of the cable.
3) The MK1 Cortina has only one fuse as standard. It is a 5 Amp in-line fuse next to the flasher unit.
Wire thickness, specifications, and uses:-
Wire grade or thickness Current rating for CONTINUOUS use.
See Note 1
Typical uses 23/ 0.0076 inch
9/ 0.012 inch
14 / 0.010
14 / 0.012
4 - 5 amps
Sidelights, rear lights, interior lights, clock, radio or tape player, anti-theft devices, alarms etc. 28 / 0.012
35 / 0.012
maximum of 14/ 15 amps Headlamps, wiper motor, heater fan, spot-lamps, fog-lamps, heated rear window 44 / 0.012
65 / 0.012
25 - 30 amps Battery charging circuits (dynamo) , horn, cigar lighter, ammeter. 97 / 0.012 45 amps Main charging circuit on alternator cars 37 /0.036
350 - 700 amps Main battery lead and lead to starter motor.
1) Wiring carrying an electrical "load" will experience a small rise in temperature. For this reason, wiring is often rated in amps using the phrase "for continuous use."
2) The first number in the wire grade column refers to the number of strands of wire. The second number refers to the thickness of each strand in thousandths of an inch. The following table gives some metric equivalents.
3) Use these sums to work out current and power:-
Current (I) = Volts (E) / Resistance (R)
Power (W) = Current (A) X Volts (E)
Current (A) = Power (W) / Volts (V)
For example, a 55 watt headlamp will draw 55/12 = 4.59 amps. (Remember, you will have 2 headlamps in the circuit!) Fitting a 75 watt headlamp would increase the current drawn to 75/12 = 6.25 amps.
See my Ohms Law calculator here
Wiring for anyone who speaks metric:-
Wire diameter Wire cross-section Continuous Current Rating / Uses 9 / 0.30 mm 0.65 sq mm 5.75 amps - Side lamps, tail lamps, reversing lamps, horns, etc 14 / 0.30 mm 1 sq mm 8.75 amps - Side lamps, tail lamps, reversing lamps, horns, general wiring. 28 / 0.30 mm 2 sq mm 17.5 amps - Headlamps, fog/driving lamps, windscreen wiper motor etc. 44 / 0.30 mm 3 sq mm 27.5 amps - Charging cable, battery feed, etc 65 / 0.30 mm 4.5 sq mm 35 amps -Charging cable for alternator, dynamo, etc 84 / 0.30 mm 6 sq mm 42 amps - Charging cable for alternator, dynamo, etc 97 / 0.30 mm 7 sq mm 50 amps - Heavy duty alternator, etc. 120 / 0.30 mm 8.5 sq mm 60 amps - Heavy duty alternator, etc. 80 / 0.40 mm 10 sq mm 70 amps - Heavy duty alternator, etc. 37 / 0.71 mm 15 sq mm 105 amps - Starter/ Battery cable 37 / 0.90 mm 25 sq mm 170 amps - Starter/ Battery cable 61 / 0.90 mm 40 sq mm 300 amps - Starter/ Battery cable
More wiring data:-
Resistance in ohms/metre
5 0.5 0.20 0.0838 6 0.6 0.28 0.0582 8 0.8 0.5 0.0328 10 1.0 0.8 0.0210 14 1.4 1.54 0.0107 16 1.6 2.0 0.00819 20 2.0 3.14 0.00524 25 2.5 4.91 0.00335
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The best people I have found for vehicle wiring products, are surprisingly enough,
Vehicle Wiring Products,
9 Buxton Court, Manners Industrial Estate, Ilkeston, Derbyshire, DE7 8EF, UK. Telephone 0115 9305454. -- Tell them I sent you ! Tommy Sandham
A good book to get you started on vehicle electrics is "Electrical Systems, including Tapes and Radios" by David Rowlands. This is Autobook 651 (ISBN 0 85147 576 0). Mine was published in 1975, so is good for "our" cars! -- Tommy Sandham