You don't have to use anything but a circuit tester on the glow plugs in this year.

Hook the clip to the positive batter terminal and touch the glow plug, be careful not to touch anything that could ground it like the engine or metal injection lines and if it lights up its good, if not its out. Pretty simple huh?

The other method of checking the glow plubs by ohms it for 1979 and later.

Good Luck

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Ryan
1985 300D Turbo Diesel
1984 200 Euro