1.9 watercooled temp sender wiring fault?

[Heimdall]

Hi

My temp gauge stopped working so i replaced the sensor/sender but it didnt fix. Ive checked on the haynes maual wiring diagram and it shows that the sensor has a brown wire and a red/yellow wire that leads up to the gauge. My sensor however, has the brown but also a lilac/black wire instead of the red/yellow. This leads into the junction box at the back of the engine bay and goes to a relay and not a connector plug. Does anyone know what the relay does? Also if i short the red/yellow to the lilac/black, the temp gauge reads half but even when cold. Cheers

[bigherb]

There are two sensors on the thermostat housing. The one at the front should be the one you want not the one in the side, they work differently so put the correct sensor back in the lilac/black position.