whats the best way of testing glow plugs?

[Morephun]

in the morning I get spanner light on and it goes out after a while....replaced one end of last year , looks like another has gone..this vec causing loads of bother at the minute. cheers guys

[bladeage1]

You should test the resistance using a circuit tester but to be honest I am not sure what the correct resistance should be but it will be on the forum somewhere.

[mrk]

iirc its about 3 or 4 ohms

[AntSSSS]

I always replace all 4 when one fails - as the others will be not far behind.

I also think these should be a 60k (ish) service item. they swell when covers 100K's of miles and thats what causes them to break in the head when removed,