Ford Edge Preheating Lamp and Smoke

Whoa, that sounds messy! That smoke on acceleration isn't good. I'm no expert, but have you checked the voltage at the glow plugs? Maybe one is dead, even if the control unit is throwing errors? Also, what kind of smoke is it? Black, blue, or white? That could give you a clue.

I haven't checked the voltage at the glow plugs. How do I perform this check safely? The smoke is black. Does that provide any further insights?

Okay, black smoke usually means you're running rich – too much fuel, not enough air. That could be related to the glow plug issue if the engine's struggling to start properly when cold, but it also points to other problems like a faulty sensor messing with the fuel/air mix. As for checking the voltage, honestly, if you're not super comfortable with electrical stuff, it's probably best left to a pro. You can easily fry something (or yourself!). Given the black smoke and the preheating light staying on, it's probably best to get it to a workshop. They can diagnose the root cause properly.

I appreciate the advice. Given the potential complexities and the risk of causing further damage, I will bring the vehicle to a workshop for professional diagnosis. The glow control unit was indeed defective, traced back to a faulty plug connection as I suspected. The repair cost 95€.