Your on the right track, there is no fixed glow plug time / timer, its controlled by the ECM

With ref if needed or not............well make up your own minds........

The 4 glow plugs are located in the engine block on the inlet side, in cylinder 1 to 4. Cylinder 5 has no glow plug. The
glow plugs are a vital part of the engine starting strategy.

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In the event of a glow plug failure any of the following symptoms may be observed:
Difficult starting.
l Excessive smoke emissions after engine start.

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Land Rover seem to think they are quite important, granted in the summer not really needed you can flick the key with no issues, but when its cold like recently, they do help and its obvious when you come to start. I always wait for the light, no matter what time of year / temp it is.

The received wisdom (not just for Landies) is that using the glo plugs helps minimise engine wear. I'm not too sure why though

cold start with glow plugs stops bore wash and reduces wear, also stops Diesel knock where fuel doesn't ignite correctly

fanatic said:

cold start with glow plugs stops bore wash and reduces wear, also stops Diesel knock where fuel doesn't ignite correctly

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Now I know. Ta.