EGR Function (Close)

SYSTEM DESCRIPTION
This system outs and controls vacuum applied to the EGR valve to suit engine operating conditions. This cut-and-control operation is accomplished through the ECM and the EGRC-solenoid valve. When the ECM detects any of the following conditions, current flows through the solenoid valve. This causes the port vacuum to be discharged into the atmosphere. The EGR valve remains closed.
- Low engine coolant temperature
- Engine starting
- Engine stopped
- Engine idling
- Excessively high engine coolant temperature
- Mass air flow sensor malfunction


COMPONENT DESCRIPTION





Exhaust gas recirculation (EGR) valve
The EGR valve controls the amount of exhaust gas routed to the intake manifold. Vacuum is applied to the EGR valve in response to throttle valve opening. The vacuum controls the movement of a taper valve connected to the vacuum diaphragm in the EGR valve.






EGRC-solenoid valve
The EGRC-solenoid valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the coil in the solenoid valve is energized. A plunger will then move to flow the vacuum signal [from the intake manifold collector to the EGR valve.]

The vacuum signal passes through the solenoid valve. The signal then reaches the EGR valve. When the ECM sends an OFF signal, the plunger is returned by the spring which cuts the vacuum signal.






CONSULT REFERENCE VALUE IN DATA MONITOR MODE
Specification data are reference values.






ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values, and are measured between each terminal and (25) (ECCS ground).









ON BOARD DIAGNOSIS LOGIC
If the absence of EGR flow is detected by EGR temperature sensor under the condition that calls for EGR, a low-flow malfunction is diagnosed.

It EGR temperature sensor detects EGR flow under the condition that does not call for EGR, a high-flow malfunction is diagnosed.



DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

CAUTION: Always drive vehicle at a sate 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.
- During the test, P0400 will not be stored in ECM even though "NG" is displayed on the CONSULT screen.

TESTING CONDITION:
Always perform the test at a temperature of -10°C (14°F) or higher.












With CONSULT
(1) Turn ignition switch "ON".
(2) Check "COOLAN TEMP/S" in "DATA MONITOR" mode witch CONSULT.
Confirm COOLAN TEMP/S value is within the range listed below.

COOLAN TEMP/S: Less than 40°C (104°F)

If the value is out of range, park the vehicle in a cool place and allow the engine temperature to stabilize. Do not attempt to lower the coolant temperature with a fan or means other than ambient air. Doing so may produce an inaccurate diagnostic result.

(3) Start engine and let it idle monitoring the value of "COOLAN TEMP/S". When the engine coolant temperature reaches 70°C (158°F), immediately go to the next step.
(4) Select "EGR SYSTEM P0400" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT.
(5) Touch "START".
(6) Accelerate vehicle to a speed of 40 km/h (25 MPH) once and then stop vehicle.
If "COMPLETED" with "OK" appears on CONSULT screen, go to step 9).
If "COMPLETED" does not appear on CONSULT screen, go to the following step.

(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. Maintain the conditions until "TESTING" changes to "COMPLETED". (It will take approximately 30 seconds or more.)

CKPS-RPM (POS): 1,500 - 2,300 rpm (A/T)
1,700 - 2,400 rpm (M/T)
Vehicle speed: 10 km/h (6 MPH) or more
B/FUEL SCHDL: 2.5- 4 ms (A/T)
2.3 - 3.7 ms (M/T)
THRTL POS SEN: (X + 0.37) - (X + 0.6) V (A/T)
(X + 0.30) - (X + 0.81) V (M/T)
X = Voltage value measured at step 7)
Selector lever: Suitable position

If "TESTING" is not displayed afier 5 minutes, retry from step 2).

(9) Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS". If "NG" is displayed, refer to "DIAGNOSTIC PROCEDURE".







Electrical Diagrams






Circuit Connectors

1 Of 2:

DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION






EGR valve
Apply vacuum to EGR valve vacuum port with a hand vacuum pump.
EGR valve spring should lift.
Check for sticking.
If NG, repair or replace EGR valve.









EGRC-solenoid valve
Check solenoid valve, following the table as shown below:
If NG, replace the solenoid valve.












EGR temperature sensor
Check resistance change and resistance value.
If NG, replace EGR temperature sensor.






EGRC-BPT valve
1. Plug one of two ports of EGRC-BPT valve.
2. Vacuum from the other port and check for leakage while applying a pressure above 0.981 kPa (100 mmH2O, 3.94 inH2O) from under EGRC-BPT valve.
3. If a leakage is noted, replace the valve.