Diagnostic Overview - Dual Stage Engine Oil Pump Solenoid
It is important to note that the Stuck On and Stuck Off diagnostic calibrations are reversed from the fault code descriptions. Reading what the diagnostic is checking for as a failure mode will appear to be opposite of what the fault description is calling out. Meaning that the Stuck Off diagnostic test is actually checking for a Stuck On condition, and the Stuck On diagnostic test is actually checking for a Stuck Off condition. This IS NOT incorrect.
The PCM performs multiple diagnostics for the Dual Stage Engine Oil Pump and solenoid. The HSD control circuit is monitored for opens and shorts. The PCM also performs diagnostics to detect if the pump is stuck in the high or low operating mode. The PCM checks the rationality of the Engine Oil Pressure Sensor before the Oil Pump Solenoid stuck on/off diagnostic runs. Typically a faulty EOP Sensor will set a fault and disable the Oil Pump Solenoid stuck on/off diagnostic.
- Stuck off Diagnostic: During higher engine speeds the PCM commands the Oil Pump Solenoid off (high mode) and monitors for the engine oil pressure to be too low.
- Stuck on Diagnostic: At idle, or lower engine speeds the PCM commands the Oil Pump Solenoid on (low mode) and monitors for the engine oil pressure to be too high.
Component or system rationality diagnostics are typically designed to detect a mechanical failure in the component (solenoid, motor, actuator) or overall system performance issue. A circuit fault against a component or sensor being used to monitor the system should be diagnosed before a rationality fault. However, do not assume that the wiring or circuits are good if you do not have a circuit fault. In some circumstances a circuit issue could also cause a rationality fault to set without a circuit fault. Rationality faults are designed to catch any failure that could be missed in other diagnostics. An example could be a small amount of resistance in the power supply, control or ground circuit to a component, usually at the harness connector terminals, that could cause a component not to energize when commanded on. In many cases a few ohms of resistance at a connector may not cause a circuit fault to set. It is always a good practice to learn and understand how the rationality checks are performed and the faults are detected. Then check the connectors and circuits for the wiring conditions that could cause that failure mode (open or shorted circuit) before replacing any components.
Since the Engine Oil Pump operates in high mode when the solenoid is not energized (off), it is more likely for a P06DE-Engine Oil Pressure Control Circuit Stuck On fault to set due to a wiring or connector issue on this system. The P06DE fault detects a pump stuck in high mode failure.