Trouble Starting 1996 C280

[MikeD]

My 1996 C280 (sport edition) cranks but will not start, and the central locking and air systems are not working.

Here are the symptoms:
1) Engine cranks but will not start
2) Central locking system not working
-No vacuum pump sounds when trying to lock/unlock
-Car locks/unlocks front driver's side only with key
-Lock/unlock button in center console has never worked
-Trunk can lock/unlock manually using key
-Infrared light on key fob illuminates when pressed but no response from car (no vacuum sounds, lights on mirror, etc.)
3) Pressing buttons to switch air vents on Digital Climate Control does not work
-Digital CC can be cycled through various air directions but continues to blow from same vents
-Again, no vacuum pump sounds when switching between air vents

I have tried changing the vacuum pump located in the car, but this did not change anything or fix the problem. I checked for disconnected vacuum hoses at the pump, throttle body, and front of the engine block. I checked the fusebox on the driver's side under the hood, and no fuses were bad. Has anyone experienced a similar issue or know what might be wrong?

[Sulaco]

Check all fuses and relays first. Could also be dead aux pump in the trunk. Have any of those features worked when the engine was running?

[MikeD]

Embarrassing enough, it was just that the fuse for the central locking system was blown. I guess I looked over that one when I initially checked the fuses!

[berwyn83]

Had the same problem and the crank position sensor was the culprit.