DTC 53
Code 53 "EGR System":
Wiring Diagram - EGR System:
CODE 53 EGR SYSTEM MALFUNCTION
(California only)
Circuit Description:
The ECM operates a solenoid to control the Exhaust Gas Recirculation (EGR) valve. This solenoid is normally closed. By providing a ground path, the ECM energizes the solenoid which then allows vacuum to pass to the EGR valve. The ECM monitors EGR effectiveness by de-energizing the EGR control solenoid thereby shutting off vacuum to the EGR valve diaphragm. With the EGR valve closed, manifold vacuum will be greater than it was during normal EGR operation and this change will be relayed to the ECM by the MAP sensor. If the change is not within the calibrated window, a Code 53 will be set.
The ECM will check EGR operation when:
Vehicle speed is above 50 mph.
Engine vacuum is between 40 and 51 kPa.
No change in throttle position while test is being run.
TCC "ON."
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
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 test 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. With the ignition "ON" and engine stopped, the ECM normally grounds terminal "T" to energize the EGR solenoid. This step checks for a defective (always open) solenoid or an electrical circuit problem.
6. The EGR solenoid is normally de-energized with the engine idling at normal operating temperature. This step checks for a defective (always closed) solenoid or an electrical circuit problem.
7. This step determines whether ECM is providing ground to terminal "T" or CKT 435 is shorted to ground.
Diagnostic Aids:
Vacuum lines should be thoroughly checked for internal restrictions. The ECM uses the pressure sensor for checking EGR operation. If there is a question of pressure sensor accuracy use pressure sensor check CHART C-1D. If no problems are found, refer to "Intermittents" in DIAGNOSIS BY SYMPTOM - NO TROUBLE CODE STORED.