I'm re-wiring the dash on a Cooper S with usual S speedo, Smiths temperature gauge and Smiths oil pressure gauge.

Haynes manual wiring diagram (p207 in my edition) says there should be three connections on the instrument regulator. The diagram says 2 green wires go from "B" terminal, one to wiper motor, one to fuse box. Two wires go from another terminal, one to fuel gauge, one to temperature gauge. Then a wire goes to earth from a third terminal.

My instrument regulator has four spade connections. Two are joined on a terminal marked "B" and two are joined on a terminal marked "1". I am guessing wires to wiper motor and fuel gauge go to terminal marked "1"? As the regulator is mounted on the speedo and there seems to be an earth connected to the speedo, does that mean there is no need for a third terminal for earth?

Finally, to which of the two terminals on both the fuel gauge and the temperature gauge do I connect wires from the respective sender units - or does it not matter?

Thanks from a newbie.

Oh I know this one!

Voltage regulator - job is to regulate the voltage to the temp gauge and the fuel gauge. So it has 12V in and puts out around the 9.5V mark or there abouts.

Reason - NFI but that's the way the Smiths guges were made and they needed the lower voltage to read correctly.

So you should have 2 sets of terminals one set is marked "B" - that stands for "Battery" and is the 12volt supply into the regulator [dark green wires].

The other set of terminals is marked "I" [as in "eye"] and stands for "Instruments" - one wire to temp gauge and the other to the fuel gauge [light green wires]

Tthe sender wires go direct to the instruments, the regulator is only to step down the voltage of the power supplied to the gauges

Hope it helps
Dat

thank you!!

1 The Haynes manual is for UK built cars and doesn't necessarily apply to OZ built cars. Get an OZ w/shop manual with OZ wiring diagrams.
If I remember correctly, and I am NOT 100% certain on this, the way the wires are laid out is slightly different between MK1, MK1.5 and MK2 Cooper 'S' cars. The MK1 uses a different wiper motor to the MK1.5 and MK2 cars. The voltage stabilizer is also slightly different as the mounting bracket is different on MK 2 cars.
2 The 1 is an I (Instrument)
3 The E (earth) terminal is actually the metal case. It is attached to the metal body of the speedo housing. The speedo housing is connected to a body earth.
3 There are green wires everywhere. The supply from the fuse box goes to B (Battery). The supply to the wiper motor goes from B to the wiper motor. The supply to the 2 gauges goes from I to each gauge.
4 The voltage stabilizer is to supply an average 10 Volts to the fuel and temp gauges. The gauges work on a Bi-metallic strip principle. As the strip is heated it bends and alters the needle position. This is heated by a current dependant on the resistance of either the temp sensor or fuel tank sender. As the level of fuel or temp changes the current flow through the gauge changes and the heating of the Bi-metallic strip changes and hence the indication changes. This requires a constant voltage to work properly. The voltage stabilizer also works on a Bi-metallic principle and produces an AVERAGE voltage of approx 10 Volts. Because it is an AVERAGE voltage the instruments are very slow to respond otherwise the reading would change each time the Votage stabilizer output voltage varied.
The point of all this is that it doesn't matter which way you make the connections at the gauges.

Regards
RonR

Thank you Ron. Very helpful.