Diagnostic Procedures
NOTE:
After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST procedures to ensure all electronic engine control systems are working properly and DTCs are no longer present.
NOTE:
Exhaust Back Pressure Regulator (EPR) is not used on F650-750.
Perform this test when directed by QUICK TEST. This test is only intended to diagnose the following components and circuits:
- Exhaust Backpressure Regulator (EPR)
- Wiring Harness Circuits (PWR GND & EPR Signal)
- Powertrain Control Module (PCM)
Valve position is controlled by switching output signal circuit to 12 volts inside PCM. ON/OFF time is dependent upon exhaust backpressure.
- Output Functions
EPR is a variable position valve that controls exhaust backpressure during cold ambient temperatures to increase cab heat and decrease amount of time needed to defrost windshield. PCM uses measured exhaust backpressure, intake air temperature and engine load to determine desired exhaust backpressure. - Detection & Management
An open or shorted to ground control circuit can be detected by an on-demand output circuit check performed during KOEO ON-DEMAND SELF-TEST. An exhaust backpressure step test, in which PCM commands and then measures specific preprogrammed pressures, is performed during KOEO ON-DEMAND SELF-TEST. If PCM detects an Exhaust Back Pressure (EBP) or Intake Air Temperature (IAT) sensor fault, it will disable exhaust backpressure regulator.