The function diagram for the IPR includes the following:
• Engine Oil Temperature (EOT) sensor
• Injection Control Pressure (ICP) sensor
• Manifold Absolute Pressure (MAP) sensor
• Barometric Absolute Pressure (BAP) sensor
• Camshaft Position (CMP) sensor
• Crankshaft Position (CKP) sensor
• Accelerator Position / Idle Validation (APS/IVS) sensor
• Electronic Control Module (ECM)
The IPR valve controls oil pressure in the high-pressure injection control system that actuates the injectors. The IPR valve consists of a solenoid, poppet, and a spool valve assembly. The IPR is mounted in the body of the high-pressure pump. The ECM regulates ICP by controlling the ON/OFF time of the IPR solenoid. An increase or decrease in the ON/OFF time positions the poppet and spool valve inside the IPR and maintains pressure in the ICP system or vents pressure to the oil sump through the front cover.
NOTE: The engine may not operate with an IPR fault, depending on the mode of failure.