[Mgs] What is this part?

[Paul Hunt]

The instrument voltage stabiliser is inside the cabin, is about a quarter the
size of that and had green and light-green/brown wires.  The starter relay
should be on the right-hand inner wing by the fusebox, not the firewall.
Off-hand I can't think of any electrical components on the firewall after the
D-type OD relay and vacuum switch (several wires) on the left-hand (facing
forwards) side, and the later fuel pump inertia switch.

Whilst green is fused ignition, red is parking lights, and you would never
normally have the two connected together so it looks like an aftermarket gizmo
or PO bodge.  Unlikely to be a relay, it *could* be a ballast resistance to
power the headlights on dim when the parking lights were on, some cars of the
80s had a similar system, but only when the ignition is on.  Or possibly a
2-stage resistor for the heater fan.

The thing to do is disconnect the wires from the device and either see what no
longer works, or measure the voltage on each wire with each electrical circuit
in the car powered on and off in turn.  Assuming you can't trace the wires to
see where they go, of course.

PaulH.
  ----- Original Message -----
  ... It  is
  located in the engine compartment on the passenger side(left hand  drive) on
the
  firewall.  It is about 5-inches below the windshield  washer reservoir(and
  heater fan motor), has one red and two green wires attached  and is about 2
1/2
  inches wide.