COMPONENT LOCATION
GENERAL DESCRIPTION
At Commom rail diesel engine, rail pressure regulator is controlled based on rail pressure sensor signal in order to maintain optimum rail pressure according to current engine rpm and load.
However when the problem that leads rail pressure to out of target value intended by ECM occurs due to mechanical or electronical reason, ECM shuts engine down and sets DTC by limiting fuel (stops injector operation) in order to prevent engine from being controlled abnormally. "rail pressure monitoring error" is the DTC which diagnose 1).supplying state of low pressure fuel and 2).mechanical operating conditions of high pressure pump and 3).rail pressure regulator indirectly based on rail pressure sensor output voltage and rail pressure sensor duty. thus, repair relavant to this DTC requires mechanics the total understand of fuel system.
DTC DESCRIPTION
P1186 is set when the rail pressure is lower than the specified minmum value for each engine speed ( 800RPM : 120bar, 2000RPM : 180bar, 3000RPM : 230bar, 4000RPM : 270bar ). This code is due to 1) rail pressure regulator sticking at closed position and valve seat wear 2) excessive fuel leakage of injectors 3) abnormal fuel pumping quantity at high pressure pump 4) insufficient fuel supply from low pressure pump.
DTC DETECTING CONDITION
Item | Detecting Condition | Possible Cause |
DTC Strategy | Voltage monitoring
| Fuel pressure regulator sticking Fuel pressure regulator circuit Fuel leakage from injectors Abnormal fuel pumping quantity at high pressure pump Clogged fuel filter
|
Enable Conditions | Engine run(when engine speed is above 700RPM)
|
Threshold Value | when the rail pressure is lower than the specified minmum value for each engine speed ( 750RPM : 120bar, 2000RPM : 180bar, 3000RPM : 230bar, 4000RPM : 270bar )
|
Diagnostic Time | Crank rotates 30 times
|
Fail Safe | Fuel Cutt | YES | |
EGR Off | NO |
Fuel Limit | YES |
MIL | YES |
MONITOR SCANTOOL DATA
Monitoring Rail pressure data
Connect scantool to Data Link Cable (DLC).
Warm engine up to normal operating temperature.
Turn "OFF" electrical devices and A/C.
Monitor "FUEL PRESSURE" parameter on the scantool
Monitoring Rail pressure sensor graph mode
Disconnect Rail pressure regulator connector of high pressure pump
Disconnect Injector connectors of all cylinders.
Monitor Rail pressure data (Graph mode) as cranking for Approx. 5~10 sec.
Is the current data displayed correctly ?
? Go to "VERIFICATION OF VEHICLE REPAIR"
Check low pressure line for being clogged (clogged fuel filter or folded fuel hose) |
Check junction of High pressure pump for fuel leakage |
Check Injector return line for fuel leakage ? If all cheking point written above is normal, after replacing High pressure ASSY' and Go to "VERIFICATION OF VEHICLE REPAIR" procedure |
TERMINAL AND CONNECTOR INSPECTION
Electrical systems consist of a lot of harness and connectors, poor connection of terminals can cause various problems and damge of component.
Perform checking procedure as follows.
Check damage of harness and terminals : Check terminals for contact resistance, corrosion and deformation.
Check connecting condition of ECM and component connector : Check terminal seperation, damage of locking device and connecting condition between terminal and wiring
noteDisconnect the pin which requires checking at mail connector and insert it to the terminal at female connector for checking connecting condition ( after checking, reconnect the pin at correct position )
Is the problem found?
? Repair the trouble causing part and go to "Verification of Vehicle Repair"
? Go to "Circuit Inspection " or "Component Inspection"
CIRCUIT INSPECTION
Rail pressure sensor circuit Inspection
Refer to P0192,P0193,P0190
Rail pressure regulator circuit Inspection
Refer to P1182,P1183,P1184
COMPONENT INSPECTION
Rail pressure sensor Component Inspection
Refer to P0192,P0193,P0190
Rail pressure regulator Component Inspection
Refer to P1182,P1183,P1184
Injector Component Inspection
Refer to P0261~P0272
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault is corrected.
After connecting scantool select "Diagnostic Trouble Codes(DTCs)" mode to and then clear DTC.
Drive the vehicle within DTC Enable conditions in General information.
After selecting "Diagnostic Trouble Codes(DTCs)" mode and check DTC is recorded again.
Are any DTCs recorded ?
? Go to the DTC guide of recorded No. in scantool.
? System operates within specification.