Component Diagnosis Charts - C3 System

- Chart C-7C EGR Valve Check.:

- Wiring Diagram for Chart C-7C EGR Valve Check.:

CHART C-7C EXHAUST GAS RECIRCULATION CHECK (VIN Y & 9)

CIRCUIT DESCRIPTION
The Exhaust Gas Recirculation (EGR) valve is controlled by a normally open solenoid (allows vacuum to pass when de-energized.)
When the ECM energizes the solenoid, by completing a ground circuit, the EGR is turned "OFF". The ECM controls EGR based on the following inputs:
a. Coolant Temperature
b. Throttle Position
c. Engine RPM
d. TCC State
e. Barometric Pressure

CHART DESCRIPTION
1. This tests for restricted valve or passage in manifold. Engine should run roughly or stall as valve is opened manually.
2. EGR valve diaphragm should begin to move as the engine speed approaches 2000 RPM.
3. This step should result in the EGR solenoid being energized, shutting off vacuum to the EGR valve diaphragm. This indicates EGR system is functioning properly.
4. Vacuum below 23.6 kPa (7" HG) at 2000 RPM is insufficient for proper EGR operation. Lower vacuum readings require repair.
5. Disconnecting the four wire EST connector with diagnostic terminal grounded causes ECM to ground CKT from ECM terminal "T" to EGR solenoid terminal "B". The light should be on.(EGR vacuum off.)
CSteps 1, 2, and 3 represent an EGR system operation check.