a 12 volt bulb like a turn signal bulb, one lead to a glow plug, the other to ground. Test the brightness of the bulb on the battery first, then watch the brightness across the glow plugs when glowing, it should be slightly dimmer. If it is very faint, then you have battery or connection problems.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked