Did you hear your glow plug relay click? Is so, good chance it's funky contacts in the power relay in the glow plug controller. Clean it up with sand paper and see if that helps. I had this problem in my other diesel and sanding the contacts fixed it. It's also happening to my 300D (a few days ago- been very cold here also) and I will try the sanding trick again.

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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