Common Failures with 272/273 Engines, ME97

I'd be interested to find out more about your passthrough programming and can coding. Do You do other modules?what is the cost associated with it. Good read btw

I've never run into it on a Mercedes but similar situation on BMW. If you're doing a valve cover/gasket and forget the ground wire at the cover and start it you are toast. You get oil level codes, BSD, and alternator codes. Order a new DME.

So Drewtech is now doing Mercedes or is it through Farsight? Are you able to do all modules on all years (OBD2)?

Mike

I have seen to O2 senor, alternator, and Throttle faults. I tried to go through BBA reman to get it repaired and after 3 attempts I was finally returned my customers money. 

One note about this although it is a rare situation, it's possible to have the 1337 Alternator Serial Interface code without an alternator, wiring, or ME module problem on certain vehicles.

If the vehicle is California Emissions it may be equipped with a Premair sensor which monitors whether a special ozone reducing radiator is installed or not. The ME monitors the Premair sensor for circuit faults and also for rationality; it detects if the temperature of the radiator is following the expected performance of the cooling system.

That Premair sensor is connected to the alternator LIN inside the engine module (M272/ME97) and sometimes it shorts the LIN bus to voltage. A normal voltage reading for the LIN bus is generally 7-8 volts (officially it's 7.5-10) and this depends on whether the system voltage is from the alternator or the vehicle battery as the LIN voltage thresholds are set at a percentage of system voltage, not a specific voltage. A stable/incorrect voltage on the LIN wire is a tip off that the circuit has a fault but what you really want to do is unplug the Premair sensor and check if the alternator code goes away.

You can check the LIN voltage before and after disconnecting the Premair sensor for confirmation it is shorting the line. LIN voltage should not change dramatically as components are added and removed.

I have seen this a few times now and other technicians have seen it as well, sometimes the sensor or wiring is damaged in a collision. The other code you are likely to see together with 1337 is 1897 "The Premair Sensor has a Sporadic Malfunction"

Hope this helps

… S-Class

Something we see pretty commonly. I usually don't document it however.