There must be a pin-out diagram on the net somewhere, but your 4 wires usually consist of:
A thick wire with a red tracer = +12V
A thick brown wire = Engine or chassis ground.
A thick brown wire with a tracer colour = Engine or chassis ground.
A thin wire = ECU signal.
Do a continuity check with a multimeter on the brown wires to the battery and the engine. If you get beeps, then 100% the red wire is 12V and the thin one is ECU.