We have a customer with a 2000 Mercedes-Benz ML 320 that has been complaining about their vehicle stalling and not re-starting for periods of 15 minutes. We checked with other competing forums such as BenzWorld.org and Mercedes shop with no apparent help what-so ever. We did notice that when the vehicle was hot and it would not start there was NO SPARK going to the plugs.
What we did find was information pertaining to the CPS or "Camshaft/Crankshaft position sensor." There are two of these sensors found on the ML 320. One is located on the passengers side head and the other is located on the drivers side of the bell housing back behind the drivers side head.
We removed these sensors to inspect them visually for any sorts of problems. I have attached photos. Whats important to remember is that the bolts that hold them on are an inverted torx "E8".
The sensor on the transmission bell housing behind the drivers side cylinder head is called the "Crankshaft reference/position sensor". This little bugger is in a real tight spot. You must use a 5 or 6 inch extension on a 1/4 drive E8 socket with a 1/4 ratchet. Take off the plastic engine cover and perch on the center of the intake or you wont be able to see it. Once the inverted torx bolt has been removed it pulls from the transmission rather easy. Installing it you must draw the sensor down with the bolt, rather than push the sensor down and start the bolt. (Two wire connector)
The sensor on the front passengers cylinder head is the "Camshaft reference/position Sensor" and the bolt that holds it on is rather hard to remove and must have had thread lock compound installed from the factory. BE VERY CAREFUL REMOVING THIS BOLT as it could snap off in the head. I recommend being easy with it and unscrewing it, screwing it back, working it ever so carefully. Also remember that this sensor has an oil seal that you must be careful with and re-use. (Three wire connector)
After testing both the Crankshaft and Camshaft Position Sensors while Cold and Hot we found that the CRANKSHAFT POSITION SENSOR failed to supply a signal to the ECM while hot (90C).
