warden,

On the MB diesel the light goes off in the cabin when the car can be started. The glow plugs continue to glow after the indicator light stops from 15 to 40 seconds depending on the temp. I used to get rough starts even in warm weather until I learned this fact. I thought that the glow plugs turned off when the cabin light turned off so I would turn it over once it would shut off. Now I just give it a good ten count even in the summer and it starts up great, no smoke or rough idle.

To check the glow plugs I am not sure. I guess that you could ohm test them but I would suggest just replacing them if you think that you are having any problems or live in a climate that can get cold. When ever I get a used diesel I always change out the glow plugs, They are pretty cheap.


Good luck

bob c