Originally Posted by Johnhef

fuse is in the relay box, just remove the cover and check it closely.

quick-n-easy on testing glow plugs is to remove the connector leading off the relay to the plugs and you'll see it numbered 1 thru 6. get your meter, set to resistance and check each of them while grounding the other test lead. anything up to 1 ohm is good, anything way over that or open circuit is bad.

for example- I just did plugs on the SDL tonight, its light wasnt coming on:
1) .8 ohm
2) .9 ohm
3) Open
4) .8 ohm
5) 16.5 ohm
6) .8 ohm

Now I'm not sure if its a set rule but most of the ones I've seen that the light fails to come on for, usually have 2 or more failing. one out and the light will usualy come on.

it's easier to just remove the intake manifold- you'll need two gaskets for going back on, unless yours are fairly new. the one I did tonight just crumbled when I took it off. You can typically get away with resuing the large green rings on the intake tubing.