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Test TC-140A: EGR System Failure

NOTE: This test applies to BE/BR bodies equipped with 5.9L diesel engines only. For connector terminal identification, CONNECTOR IDENTIFICATION . For component location and wiring diagram, see WIRING DIAGRAMS article.
  1. Using scan tool, read DTCs. If EGR SOLENOID CIRCUIT DTC is set, perform TEST TC-17A: EGR SOLENOID CIRCUIT . If DTC is not set, go to next step.
  2. Remove Intake Air Temperature (IAT) sensor. Inspect IAT sensor for excessive soot build-up. Replace IAT sensor if necessary and go to next step. If IAT sensor is okay, go to next step.
  3. Reinstall IAT sensor. Start engine and allow it to idle. Using scan tool in EGR SYSTEM TEST mode, select FLOW. Monitor IAT sensor temperature until it stabilizes. If IAT sensor increases more than 10 degrees, go to next step. If IAT sensor temperature does not increase more than 10 degrees, go to step 6)  .
  4. Condition required to set DTC is not present at this time. EGR SYSTEM FAILURE DTC sets if PCM energizes EGR solenoid and no significant change in IAT occurs. Possible causes are: open or blocked EGR valve vacuum supply, blocked exhaust transfer tube to intake manifold, failed EGR valve, failed PCM, failed connectors and terminals, or failed EGR solenoid or transducer. Go to next step.
  5. Inspect all related wiring and connectors. Repair wiring and connectors as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connectors and terminals are okay, test is complete. Perform TEST VER-2A: ROAD TEST VERIFICATION .
  6. Disconnect vacuum supply hose at EGR solenoid. If vacuum does not exist at EGR solenoid, repair vacuum supply as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If vacuum exists, go to next step.
  7. Reconnect vacuum supply hose. Disconnect EGR solenoid-to-EGR valve vacuum supply hose at EGR solenoid. Ensure EGR solenoid is still actuating. If EGR solenoid is not allowing vacuum to pass through, replace EGR solenoid and perform TEST VER-2A: ROAD TEST VERIFICATION . If vacuum is passing through, go to next step.
  8. Reconnect vacuum supply hose at EGR solenoid and disconnect it at EGR valve. If vacuum does not exist at EGR valve, repair vacuum hose or check valve as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If vacuum exists, go to next step.
  9. Remove EGR valve. Connect a vacuum pump to EGR valve. Slowly apply 10 in. Hg while observing EGR valve poppet. If poppet does not start to open at 10 in. Hg, replace EGR valve and perform TEST VER-2A: ROAD TEST VERIFICATION . If poppet opens, inspect EGR tube, and intake and exhaust manifolds for carbon build-up and repair as necessary. Retest EGR system.
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