Having trouble cranking unless block warmer plugged in. Glow plugs less than 6 mos old. Cranked very easy until recent cold weather snap(not really cold live in North Atlanta). Now won't crank even in garage w/o block warmer. Glow plug indicator comes on (don't know if this indicates anything). Purchased from MB mechanic and he said to check fuse and solenoid. However, cannot locate a fuse or identify GP solenoid. Looking for schematic and fuse panel/solenoid layout to troubleshoot from.

Would like a good shop manual. Any recommendations?

Thanks