Note this Appendix is for the Instruments fitted to Colin Ushers Robin Hood only and is not intended for general use.

Table 1 shows connections from a standard Sierra 12 pin Instrument Plug via a 'dummy' socket to a set of individual Smiths 'Classic' Instruments. For my own reasons I have used a new set of colours on my 'dummy' socket.

The Haynes manual shows a 16 pin socket to interface with the Sierra Instrument unit, which includes a Seat Belt Warning Light & 2 Economy lights. Do not take the pin locations in the Haynes manual literally, they are not the same as the actual unit. ie. Pin 5 on the Haynes diagram is pin 11 on the donor edge connector. Work only on colours. Connections to the Sierra unit are made from the PWS Orange Plug and the Warning Lights spur. The spur has paired wires, see notes below. **

Your donor edge connector may have 12 or 16 pins. If you have 16 pins ignore the unwanted pins. Marked NA in the chart below.

Pins are read left to right looking into the edge connector, with wire tails below. The PWS colours are very similar to the Haynes (Ford) colours. The colours in the ACU row are the ones used for (my) conversion to individual gauges. Use whatever you want.

Table 1

The wires highlighted in ORANGE come from the Orange Plug on the PWS loom. The Red/Blue wire is an unswitched 12 volts for Clock, Radio. Beware as these come via a Battery Master Switch so will NOT be live 100%. The Blue/Red is a sender wire for an Electronic Oil Pressure gauge, these wires are supplied by PWS for builders fitting individual instruments. ** The Brown & Black earth wires for the Warning lights are NOT required when fitting the Sierra Instrument Unit as it is earthed thro' pin 11(Brown) but will be required for individual units.

The new Dash has the following Instruments & Warning Lights. Donor Pin Numbers(*) & ACU Colours. All gauge cases must be earthed if panel lighting is required. With a metal panel this is automatic, but you must use the 'U' clamps (the brackets that secure the gauges in position) to ensure 100% reliability.

Pin 2 Black/Blue to 10 volt Voltage Regulator. Regulated output to Temperature & Fuel Gauges. 3rd terminal is earth. (see note below)

Speedometer. Lighting only. Pin 12 Brown/Red to bulb.

Rev Counter/Tacho. The Tacho counts the on/off pulses in the 12 volt supply to the Ignition Coil. No stabilizer is required. The sensor wire (White) is wrapped around a post on the outside of the Tacho. The wire comes from the 12v positive feed to the coil (remove the feed to the coil) round the sensor and then back to the coil positive terminal, completing the ignition circuit. You will need a positive supply to the Tacho, use the feed from Pin 2 Blk/B and possibly an earth. Pin 11 Brown, at the moment mine is showing double actual revs, see note below. Note if the Tacho. does not move try reversing the wires from the coil. The wire from pin 5 on the Sierra plug is not used. Illumination is from pin 12 Brown/Red to the bulb. You must buy a 4 cylinder Tacho. (marked on the dial in small letters). However see note below BEFORE you proceed.

Note:- The Tacho works but shows twice the RPM. I am advised by Speedy Cables that the older type Smiths unit (designed for contact breaker distributors) WILL NOT WORK with Electronic Ignition. (even the very early Ford pattern) These older units can be converted at a cost of £55.00. I am still working on this problem.

The Ford Square Digital Clock. For a simple digital clock the wiring is quite complicated. The clock has 4 wires with a special plug and the pins are NOT numbered in the Haynes Manual. The function of these wires is a bit obscure as an electronic clock needs power all the time (but also a very low battery drain) even with the ignition off, otherwise the clock resets every time you turn the ignition off. It also requires backlighting as the digital display is made very weak to give a low battery drain. So if we use the special Ford clock plug and colours we have - Red, fused supply direct from the battery but always on. Brown to earth. Grey/Yellow, this goes to pin 58 on the Column Lighting switch and provides illumination when the ignition is off but the sidelights are on. Black/Brown, this goes to the ignition switch Pin 15 (Black/Yellow) and supplies a +ve pulse for setting the hours and minutes and a +ve supply for illumination when the car is running. Hence so many wires. As an added feature the display illumination is dimmed when the sidelights are on. (bright in the daytime, dim at night)

Vacuum Gauge. Lighting only. Pin 12 Brown/Red to bulb.

Ammeter. Heavy Red wires from Battery Master Switch in the Alternator/Battery feed. Pin 12 Brown/Red to bulb.

Oil Pressure. From Sender on engine. Blue/Red. (sender required) The +ve supply comes via a 10 volt Regulator. Pin 12 Brown/Red to bulb. I fitted a mechanical unit.

Water Temperature. From sender on engine. Pin 6 Yellow/Red. The +ve supply comes via the 10 volt Regulator. Pin 12 Brown/Red to bulb.

Fuel Level. From sender on Fuel Tank. Pin 7 Black/White. The +ve supply comes via a 10 volt Regulator. Pin 12 Brown/Red to bulb

Warning Lights.

Main Beam. Slate. Pins 1 &11

Ignition Light. Green. Pins 10 & 2 On the Sierra there is a diode (IN5400) in the wire from the Ignition Light to Alternator. This is has the positive end (marked with a triangular shape) towards the light. Current can flow from +ve thro' the light to the Alternator but cannot flow the other way. (No diode fitted to my Robin Hood, but the Light seems to work OK)

Flasher. Green. Pin 4 Slate/Red. Pins 8 & 11 One indicator for Left & Right directions. **

Brake Fluid/Handbrake. White. Pin 9 Earthed via the handbrake micro switch.

Low Oil Pressure. Brown. Pins 3 & 2

Illuminated Rocker Switches. (locate with +ve terminal to the top)

Heater Fan. (Orange)

Bk/V = +ve, Y=A, Bn = -ve.

Twin Fog Lights. (Red)

S = +ve, S/Bk = A, Bn = -ve

Choke. None.

Europa Specialist Spares Voltage Stabilizer (Voltage Regulator) Part Number BR 1307

This device supplies the instruments with a regulated 10 volts from an input of between 10 & 35 volts. Case to Earth, B to (switched) Battery +ve, I to Instruments. (usually the Fuel and Water Temperature gauges only) The B & I terminals are doubles, so you can tap off the second B pin to supply the Tacho +ve. For the B supply use the Black/Blue wire from Pin 2 on the old Sierra Plug. See chart above.

Miscellaneous Items :-

Note:- On the original Sierra the Low Brake Fluid Switch has 3 wires coming out of a moulded rubber plug. Brown to Earth, Brown/Green ran direct to the Handbrake switch and a Brown/Yellow to the Instrument Unit at Pin 9. The PWS loom has only one Brown/Yellow spur wire, and it is suggested that you run this to the Brown/Yellow on the Fluid Warning plug, Run the Brown wire to Earth and then a Brown/Green wire runs all the way to the Handbrake switch.(The Brown/Green is not in the PWS kit) If you do not have, or are not fitting the Fluid Warning Light, (Check SVA ?) run the PWS Brown/Yellow direct to the Handbrake switch. No Earth is needed. The Handbrake switch has only one terminal as the switch has an inbuilt path to earth but CHECK the switch just in case.

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© Colin Usher 2006