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P0148-HIGH PRESSURE COMMON RAIL (HPCR) CHECKSUM
For a complete wiring diagram Refer to Section 8W.
When Monitored:
While the engine is running.
Set Condition:
A deviation between the fuel pressure set point and the actual fuel pressure.
Possible Causes
OTHERS DTC'S PRESENT
FUEL LEAKS
FUEL CONTROL ACTUATOR
FUEL PRESSURE SENSOR
CASCADE OVERFLOW VALVE
CHECK VALVE DAMAGED OR BLOCKED
FUEL RETURN LINES OBSTRUCTION, DAMAGE, OR DEBRIS
LIFT PUMP FLOW
AIR IN FUEL SYSTEM
LEAKING FUEL INJECTORS OR HIGH PRESSURE CONNECTORS
PRESSURE LIMITING VALVE
HIGH PRESSURE FUEL PUMP
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. OTHERS DTC'S PRESENT
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With the scan tool, read DTCs.
Are any other DTC's present?
Yes
Repair other DTC's first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No
Go To2
2. FUEL LEAKS
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Ensure that the fuel level is above 15% using the scan tool.
Visually inspect the low and high pressure side of the fuel system for fuel leaks or damaged components.
Do you have any fuel leaks or damaged components?
Yes
Repair the fuel leak.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No
Go To3
3. FUEL CONTROL ACTUATOR
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Check for a mechanically stuck Fuel Control Actuator (FCA). Using the scan tool, actuate the fuel control actuator.
NOTE: The fuel control actuator will only click when cycled off..
Do you hear a click from the actuator when you cycle the actuator off with the scan tool?
Yes
Go To4
No
Replace the fuel Injector pump.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
4. FUEL PRESSURE SENSOR
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Using the scan tool, monitor the fuel pressure reading from the fuel rail pressure sensor at idle and at 2000 RPM
Is the fuel rail pressure reading higher at 2000 RPM than at idle?
Yes
Go To5
No
Replace the fuel pressure sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
5. HIGH FUEL PRESSURE
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Using the scan tool compare the fuel rail pressure set point with the actual fuel rail pressure.
Is the actual fuel rail pressure higher than the fuel rail pressure set point?
Yes
Go To6
No
Go To9
6. CASCADE OVERFLOW VALVE
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Perform the no trouble code test "*fuel pump return flow test" .(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Did the fuel injection pump pass the test?
Yes
Go To7
No
Replace the Fuel pump.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
7. CHECK VALVE DAMAGED OR BLOCKED
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Check the fuel drain line check valve in the rear of the cylinder head for signs of damage, blockage, or debris.
Is the check valve damaged or blocked?
Yes
Repair the cause of the damaged or blocked check valve or replace the valve.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No
Go To8
8. FUEL RETURN LINE OBSTRUCTION, DAMAGED OR DEBRIS
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Check the fuel return lines for signs of obstruction, damage, or debris.
Are the fuel drain lines damaged or blocked?
Yes
Repair cause of high fuel drain line restriction.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No
Go To9
9. LIFT PUMP FLOW
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Perform the no trouble code "*LIFT PUMP FLOW TEST". (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Did the Lift pump pass the test?
Yes
Go To10
No
Replace the Lift Pump.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
10. PRESSURE LIMITING VALVE
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Perform the no trouble code test "*PRESSURE LIMITING VALVE ON THE FUEL RAIL FOR INTERNAL LEAKS".
Did the pressure limiting valve pass the test procedure?
Yes
Go To11
No
Replace the Pressure Limiting Valve.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
11. LEAKING FUEL INJECTORS OR HIGH PRESSURE CONNECTORS
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Perform the no trouble test "*INJECTOR RETURN FLOW TEST". (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Are any Injectors leaking or high pressure connectors leaking?
Yes
Replace or repair the leaking fuel injectors or high pressure connectors.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No
Go To12
12. HIGH PRESSURE FUEL PUMP
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Perform the no trouble code test "*HIGH PRESSURE FUEL PUMP PERFORMANCE TEST". (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Did the fuel pump pass the high pressure fuel pump performance test?
Yes
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
Replace the High pressure fuel pump.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
