W124 Diesel no start, no preheat light, blown fuse
 

I have a 1987 300TDT.

Engine cranks but won't start. Found glow plug fuse blown, replaced, it blows again. I never see the preheat light come on.

I took the controller/relay module out. Manually activated the relay. No voltage drop anywhere. I assume the control portion is fine since the fuse blows. No smell of anything burnt up.

Tested the wiring harness and each glow plug circuit. Readings for each cylinder were 0.1 ohm. I was able to test two glow plugs at the end of the plug with the wire attached, same readings.

It was getting harder to start recently and ran rough when it first started.

Now it cranks but blows fuses, no pre-glow lamp activation.

My understanding is the glow plugs fail in high resistance.

I don't see how I can get at these glow plugs without pulling the intake manifold.

Will these short due to carbon buildup in the head? Or do I have a wiring problem or is it time to remove, ream and replace the glow plugs?

0.1 ohm sounds too low

http://www.peachparts.com/shopforum/...2.46.58-am.png

https://www.dieselgiant.com/glowplugrepair.htm

This link will show you how to test glow plugs , but first unplug the six pin plug from relay so the glow plugs are not receiving power and then turn the key to see if fuse blows