P0402
SYSTEM DESCRIPTION
The EGRC-BPT valve monitors exhaust pressure to activate the diaphragm, controlling throttle body vacuum applied to the EGR valve. In other words, recirculated exhaust gas is controlled in response to positioning of the EGR valve or to engine operation.
ON BOARD DIAGNOSIS LOGIC
If too much EGR flow exists due to an EGRC-BPT valve malfunction, off idle engine roughness will increase. If the roughness is large, then the vacuum to the EGR valve is interrupted through the EGRC solenoid valve. If the engine roughness is reduced at that time, the EGRC-BPT valve malfunction is indicated.
DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
CAUTION: Always drive vehicle at a safe speed.
NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
TESTING CONDITION: For best results, perform test at a temperature above 5°C (41°F).
With Consult
1. Install vacuum gauge between EGRC-BPT valve and EGR valve as shown in the illustration.
2. Start engine and warm it up to normal operating temperature.
3. Stop engine and wait at least 5 seconds.
4. Turn ignition switch "ON" and select "EGRC-BPTN P0402" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT.
5. Start engine and let it idle.
6. Touch "START".
7. Check the output voltage of "THRTL POS SEN" (at closed throttle position) and note it.
8. When the following conditions are met, "TESTING" will be displayed on the CONSULT screen and the bar chart may increase. Maintain the conditions many times until "COMPLETED" appears.
Selector lever: Suitable position
CMPS-RPM (REF): 1,800 - 2,000 rpm (A/T) 2,200 - 2,600 rpm (M/T)
Vehicle speed: 30 - 60 KPH (19 - 37 MPH) (A/T) 30 - 100 KPH (19 - 62 MPH) (M/T)
B/FUEL SCHDL: 2.3 - 2.9 msec (A/T) 1.6 - 2.2 msec (M/T)
THRTL POS SEN: (X +0.15)- (X +0.41) V (A/T)
(X +0.25)- (X +0.38) V (M/T)
X = Voltage value measured at step 6)
- The bar chart on CONSULT screen indicates the status of this test. However, the test may be finished before the bar chart becomes full scale.
- If the bar chart indication does not continue to progress, completely release accelerator pedal once and try to meet the conditions again.
- If "TESTING" does not appear on CONSULT screen, retry from step 2).
9. If CONSULT instructs to carry out "OVERALL FUNCTION CHECK", go to next step. If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".
10. Open engine hood.
11. Raise engine speed to 2,000 - 2,400 rpm under no load and hold it. Then touch "NEXT" of CONSULT screen.
12. Check vacuum gauge while keeping engine speed at 2,400 ± 400 rpm.
Vacuum should be 0 to -150 mmHg (0 to -5.91 inHg).
If NG, go to "DIAGNOSTIC PROCEDURE".
If OK, touch "YES" on the CONSULT screen.
13. Check rubber tube between intake manifold collector,
EGR-solenoid valve, EGR valve and EGRC-BPT valve for cracks, blockages or twists.
If NG, repair or replace.
If OK, touch "YES" on the CONSULT screen.
OR
OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the EGRC- BPT valve. During this check, a 1st trip DTC might not be confirmed.
1. Install vacuum gauge between EGRC-BPT valve and EGR valve as shown in the figure at left.
2. Lift up vehicle.
3. Start engine and shift to 1st gear or 1 position.
4. Check vacuum gauge while keeping engine speed at 2000 - 2800 rpm. Vacuum should be 0 to -150 mmHg (0 to -5.91 inHg).
If NG, go to "DIAGNOSTIC PROCEDURE".
If OK, go to next step.
5. Check rubber tube between intake manifold collector, EGRC-solenoid valve and EGRC-BPT valve for misconnection, cracks or blockages.
If NG, repair or replace.
DIAGNOSTIC PROCEDURE
COMPONENT INSPECTION
1. Plug one of two ports of EGRC-BPT valve.
2. Vacuum from the other port and check leakage without applying any pressure from under EGR-BPT valve.
Leakage should exist.