Alhambra/Sharan engine pre heaters

[David Fox]

Hi I have a problem with the engine pre heaters on my 1.9TDi Alhambra/Sharan.

I have changed the glowplugs to no avail, I have (at last !) found the fuses and relays and checked these which are ok There is no power to the glowplugs when ignition is turned on although there is power to the relay and low tension fuse feeding the relay.

Is there some sort of inhibitor which is telling the glowplug power supply that they are not needed. A temp. sensor perhaps ?

I can get the car to start immediately if I manually power up the glowplugs from the battery direct.

Any clues or help would be much appreciated.

[kenney]

The glow plug relay receives information from the ECU,which in turn receives information from the engine temp sensor.Remove the contact on the sensor and see if the glow plugs function

[David Fox]

Many thanks it works now ! so I need a new water temp sensor can I leave it unplugged til i get one ?
David

[kenney]

You can try with a new sensor,not sure if it will make any difference You can not leave the connector off,because the glow system will be working,even when the engine is hot.Another matter is,it all depends on the ambient temperature if the engine needs the glow system to start.A TDI engine should start without the glow plugs working with a temp of 10 degrees or warmer,if it does not then there is something else wrong,among other things the basic setting of the timing.