P0490
DTC P0490: EGR Value (Stepper Motor) Circuit Malfunction (Battery Short)EGR Value Circuit Part 1:
EGR Value Circuit Part 2:
CIRCUIT OPERATION
The EGR valve power is supplied from the MFI relay (terminal No. 2).
The ECM (terminals No. 31, No. 32, No. 47, No. 48) drives the stepper motor by sequentially turning "ON" the power transistors in the ECM and providing ground to the EGR valve (terminal No. 1, No. 3, No. 4, No. 6).
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 not flowing through the coils 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 stored in memory for the item monitored below)
Not applicable
Sensor (The sensor below is determined to be normal)
Not applicable
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
Ignition switch is "ON" position.
Battery positive voltage is at between 10 and 16.5 volts.
Judgement Criterion
When the EGR valve is energized, the ECM voltage should be 6.7 volts or more for 1.4 seconds..
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3. OBD-II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
EGR valve (stepper motor) failed.
Harness damage.
Connector damage.
ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991658: Test Harness Set
STEP 1. Check harness connector B-12 at EGR valve and harness connector B-10 at ECM for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 2.
NO: Repair or replace it. Then go to Step 5.
STEP 2. Measure the EGR valve motor coil resistance.
1. Disconnect the EGR valve connector B-12.
2. Measure the resistance between EGR valve connector terminal No. 2 and either terminal No. 1 or terminal No. 3.
Standard value: 20 - 24 ohms [at 20 °C (68 °F)]
3. Measure the resistance between EGR valve connector terminal No. 5 and either terminal No. 4 or terminal No. 6.
Standard value: 20 - 24 ohms [at 20 °C (68 °F)]
Q: Is the measured resistance between 20 and 24 ohms [at 20 °C (68 °F)]?
YES: Go to Step 3.
NO: Replace the EGR valve. Then go to Step 5.
STEP 3. Check for short circuit to power supply between EGR valve connector B-12 and ECM connector B-10.
Q: Is the harness wire in good condition?
YES: Then go to Step 4.
NO: Repair it. Then go to Step 5.
STEP 4. Check the EGR valve operation using special tool MB991658.
1. Remove the EGR valve.
2. Connect special tool MB991658 to the EGR valve. (All terminals should be connected.)
3. Use the jumper wires to connect terminal No. 5 of the EGR valve connector to the positive battery terminal.
4. Check to ensure that the motor operates when the terminal No. 1 and No. 3 of the EGR valve connector are respectively connected to the negative battery terminal using a jumper wire.
- Vibration should be present at each application of voltage to test clip combination.
5. Then, use jumper wires to connect the terminal No. 2 of the EGR valve connector to the positive battery terminal.
6. Check to ensure that the motor operates when terminal No. 4 and No. 6 of the EGR valve connector are respectively connected to the negative battery terminal using a jumper wire.
- Vibration should be present at each application of voltage to test clip combination.
7. Reinstall the EGR valve, using a new gasket, and tighten to the specified torque.
Tighten torque: 23 ± 6 N.m [17 ± 4 ft.lb.]
Q: Is the EGR valve operating properly?
YES: Replace the ECM. When the ECM is replaced, register the ID code. Refer to ID Code Registration Judgment Table
NO: Replace the EGR valve. Then go to Step 5.
STEP 5. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 3. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0490 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.