COMPONENT LOCATION
GENERAL DESCRIPTION
5V power supply which is used in electrically controlled diesel engine is generated by constant voltage IC inside of ECM.keeping 5V at constant is necessary for precise signal detection and calculation of various sensors.ECM, monitoring this voltage, sets entire system to limp home mode (engine speed is fixed at 1250RPM) as producing DTC to prevent system from abnormal control due to the unreliable sensor signals when the voltage is beyond the specified value.
DTC DESCRIPTION
P1525 is set when voltage above 5158mV - the maximum voltage of sensor power supply2 generates from ECM - is detected for more than 0.1 sec. This code is due to short to battery in sensor power circuit or the failure of constant voltage IC inside of ECM.
DTC DETECTING CONDITION
Item | Detecting Condition | Possible Cause |
DTC Strategy | Voltage monitoring
| RPS power supply circuit APS 2 power supply circuit ECM component
|
Enable Conditions | Ignition "ON"
|
Threshold Value | when the voltage is below the minimum voltage of sensor power supply (above 5158mV)
|
Diagnostic Time | 100ms
|
Fail Safe | Fuel Cutt | NO | Limp home mode is activated (engine speed is fixed at 1250RPM )
|
EGR Off | NO |
Fuel Limit | YES |
MIL | NO |
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 "Power circuit Inspection "
POWER SUPPLY CIRCUIT INSPECTION
Check power circuit voltage
Ignition "OFF", Turn engine "OFF".
Disconnector RPS connector(C356) and APS connector(C308)
Ignition "ON"
Measure the voltage between RPS connector terminal 1 and APS connector terminal 5
Is the measured voltage within the specification?
? Go to "Component Inspection"
? Go to "2. Check short to ground in power circuit" as follows
Check short to battery in power circuit
Ignition "OFF", Turn engine "OFF".
Disconnect RPS connector(C356), APS connector(C308), ECM connectors(C333-1,C333-2)
Ignition "ON"
Measure the voltage between RPS connector terminal 1 or APS connector terminal 3 and chassis ground.
Is abnormal voltate measured in this test?
? Repair short to battery and go to "Verification of Vehicle Repair"
? If the circuit is insulated well and the sensor power supply from ECM is high, replace ECM and go to "Verification of Vehicle Repair"
COMPONENT INSPECTION
Ignition "OFF", Turn engine "OFF".
Disconnect RPS connector(C356) and APS connector(C308)
Check that sensor connector power supply is within the specification after turning Ignition "ON"
Connect RPS connector and APS connector in turn.
Does change of sensor power supply occur as connecting sensor connector?
? Replace RPS or APS
? Go to "Verification of Vehicle Repair"
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.