That sensor on the water neck isn't for the glow plugs from what we dicussed over the violet wire and the GP Relay thread...
Someone believed that it was for the heating/cooling to tell the fan (the inside one) when to not be on due to cold water in the system.

He verified this when he hooked his glow plug circuit (we have been playing around a bit) to this sensor and it was dependednt on how the heater controls we set.

Anyway the glow plugs are ambient sensed. We have been designing a circuit so that the glow plugs are water temperature dependet (do a search for that thread "violet wire")

The GP's heat more if the engine is cold but poster starter glowing is only achievable by the newer relay OR our handy dandy circuit that I came up with.

Just thought I would set things straight..