Vehicle
2014 RAM 1500 SLT 5.7L Eng VIN T
Title
MDS Cylinder #1 Shutdown at Idle
Complaint
The diagnostic scanner shows MDS #1 shutdown is always active and code P1411 is set.
Cause
The lock pin in the MDS lifter was not locking in and returning the lifter to normal operation, when the lifter was removed it was visible that the pin was not locked in or even visible. After the repair, the PCM removed power to the solenoid on its own. Even though there is nothing in the diagram that I can find, on this particular truck the PCM when detecting a failure to disengage the MDS on a cylinder, will lock that cylinder out electronically to prevent excessive clearance in the valve train.
Correction
Replaced the MDS lifter, allowing oil pressure from the solenoid to push the locking pin in place and free the lifter to collapse and regulate pressure to the valves.
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