Cortina MK1 Electrical Wiring Specifications

 

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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     7 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 61 /0.036	350 - 700 amps	Main battery lead and lead to starter motor.

Notes:- 

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:-

Metric Gauge	Diameter mm	Square mm	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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Click here to test a Lucas dynamo

Click here to time your ignition with a strobe light

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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

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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