where are the glow plugs on a 1999 1.7 diesel astr?

Glow plugs screw into head about wher spark plugs are on a gas engine ....should be close to your injectors .......
Should have a wire attached to them ....unplug wire and unscrew them counter clockwise AS like a spark plug..
You can test them by grounding the screw side and putting 12 volts to the term side ...not too long thou ..just enough to see if their heating up .....

bg
November 2005