Some people have found bad Glow Plugs testing them on the Batttery that were good when they did the Test with an Ohm Meter.
I looked for My Block Heater and could not find it. One day while I was doing something else I found the Block Heater Cord shoved up under the front Bumper and tied there.
Sure enough I have a Block Heater. It is just real difficult so see as there is a Bracket that comes down below the Turbocharger that blocks the view.
See post #9 is a pic of a Glow Plug that Ohmed out OK but was bad when tested on the Battery.
http://www.peachparts.com/shopforum/diesel-discussion/311514-glow-plugs-bad-how-tell.html