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DTC P0490-00: EGR valve (stepper motor) circuit malfunction (battery short)
 
 
 
 
CIRCUIT OPERATION
  • MFI relay is built into the IPDM E/R.
  • Power is supplied to the exhaust gas recirculation (EGR) valve connector terminal number 2 and number 5 from the MFI relay connector terminal.
  • The ECM connector terminal number 20, number 21, number 22 and number 23 makes the power transistor in the unit be in ON position, and that makes currents go on the EGR valve connector terminal.
 
 
TECHNICAL DESCRIPTION
The ECM checks whether a short circuit to the power supply exists or not by measuring the EGR valve (stepper motor) drive circuit voltage when the current is flowing through the coil of the EGR valve (stepper motor).
 
 
DESCRIPTIONS OF MONITOR METHODS
When the EGR valve (stepper motor) drive circuit voltage is over the specified range, it is judged that a malfunction exists.
 
 
MONITOR EXECUTION
Continuous.
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Exhaust gas recirculation (EGR) stepper motor monitor
Sensor (The sensor below is determined to be normal)
  • Mass airflow sensor
  • Engine coolant temperature sensor
  • Intake air temperature sensor
  • Barometric pressure sensor
  • Manifold absolute pressure sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
Check Condition
  • Output status ON.
  • 12V battery positive voltage is between 10.0 and 16.5 volts.
Judgment Criterion
  • When EGR valve is energized, the ECM voltage is more than 6.7 volts for 1.4 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
None.
 
 
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function, OBD-II Drive Cycle – Pattern 1 OBD- II DRIVE CYCLE.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • EGR valve (stepper motor) failed.
  • Shorted EGR valve (stepper motor) circuit or connector damage.
  • ECM failed.
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
1.STEP 1. Check EGR valve itself.
Check EGR valve itself [Refer to ENGINE, Engine, Motor and Emission Control – Emission Control – Exhaust Gas Recirculation (EGR) System EXHAUST GAS RECIRCULATION (EGR) VALVE (STEPPER MOTOR) CHECK].
Q: Is the check result normal?
Replace the EGR valve [Refer to ENGINE, Engine, Motor and Emission Control – Emission Control – Exhaust Gas Recirculation (EGR) System EXHAUST GAS RECIRCULATION (EGR) VALVE REMOVAL AND INSTALLATION].
 
2.STEP 2. Check harness between EGR valve connector terminal number 1 and ECM connector terminal number 20.
Check output line for short circuit.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
3.STEP 3. Check harness between EGR valve connector terminal number 3 and ECM connector terminal number 21.
Check output line for short circuit.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
4.STEP 4. Check harness between EGR valve connector terminal number 4 and ECM connector terminal number 22.
Check output line for short circuit.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
5.STEP 5. Check harness between EGR valve connector terminal number 6 and ECM connector terminal number 23.
Check output line for short circuit.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
6.STEP 6. Test the OBD-II drive cycle.
After erasing the DTC, carry out test drive with the drive cycle pattern, and recheck the DTC.
(1) Use scan tool (M.U.T.-III SE) to erase the DTC.
(2) Carry out test drive with the drive cycle pattern (Refer to Diagnostic Function, OBD-II Drive Cycle – Pattern 1 OBD- II DRIVE CYCLE).
(3) Use scan tool (M.U.T.-III SE) to recheck the DTC.
Q: Is DTC P0490-00 set?
Replace the ECM (Refer to ENGINE CONTROL MODULE (ECM) REMOVAL AND INSTALLATION).
Intermittent malfunction (Refer to GENERAL INFORMATION, General Information – How to Use Troubleshooting/Inspection Service Points – How to Cope with Intermittent Malfunctions HOW TO COPE WITH INTERMITTENT MALFUNCTIONS).