ECM-281C: Text Message. Pressure Too High (B5204T5; 2007): Fault-tracing: Verification: Verification
HINT: After carrying out the repair, check that the fault has been remedied.
- Run the engine to operating temperature. Allow the engine to idle.
- air conditioning (A/C) off
- Read off the fuel pressure and the fuel pressure desired value.
- Start the quick test when the engine is running at idling.
During the course of the quick test, the control module regulates the pressure for different target values in different steps (530, 490, 450, 410, 440, 490, 530 kPa). Each step takes 10 seconds. The test usually starts with the pressure momentarily going up to 650 kPa.
NOTE:Because the by-pass valve in the fuel pump (FP) will be open at approximately 650 kPa, the pressure will not go higher than this.
HINT: The illustration to the left shows an example of normal regulation.
- The upper digital display and the graphic display (red font color) indicate the absolute fuel pressure, calculated from the fuel pressure sensor
- The central digital display and the graphic display (blue font color) indicate the control module target value for the absolute fuel pressure
- The lower digital display indicates the relative fuel pressure (white font color), calculated from the fuel pressure sensor and the atmospheric pressure sensor (= absolute pressure minus atmospheric pressure). If a manometer is connected during the test, it must indicate this pressure.
Check that the value for absolute fuel pressure is the same as the target value for absolute fuel pressure. If the values are not the same, this indicates a fault in the pressure regulation. The values may differ during the quick test when the target value is changed. This is due to sluggishness in the fuel regulation and is normal. In some cases, it can take up to 5 seconds before the fuel pressure reaches the target value for the fuel pressure.
Is the function OK?
- YES
VERIFIED: Troubleshooting has been completed.
- NO
Refer to Information