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Home >> Jeep >> 1996 >> Cherokee Classic, Part Time, Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Tests W/Codes - 4.0L >> Diagnostic Trouble Code (DTC) Identification >> Test TC-46A - EGR System Failure

Test TC-46A - EGR System Failure

NOTE: For connector terminal identification, refer to CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article in this section.
  1. Start engine and allow it to idle. Using scan tool in EGR SYSTEM TEST mode, press No. 2 on scan tool key pad to block EGR flow. Monitor Intake Air Temperature (IAT) sensor temperature until it stabilizes. Go to next step.
  2. Press No. 3 on scan tool key pad to actuate EGR solenoid, and allow EGR to flow. Monitor IAT temperature sensor. If temperature does not increase after EGR is actuated, go to step 5). If temperature increases after EGR is actuated, go to next step.
  3. 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.
  4. Inspect all related wiring and connectors. Repair wiring and connectors as necessary and perform TEST VER-2A . If connectors and terminals are okay, test is complete. Perform TEST VER-2A.
  5. Disconnect vacuum supply hose EGR solenoid. If vacuum does not exist in supply hose, repair vacuum supply as necessary and perform TEST VER-2A. If vacuum exists, go to next step.
  6. 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 . If vacuum is passing through, go to next step.
  7. Reconnect vacuum supply hose at EGR solenoid and disconnect it at EGR valve. If vacuum does not exist in hose, repair vacuum hose or check valve as necessary and perform TEST VER-2A. If vacuum exists, go to next step.
  8. 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 . If poppet opens, inspect EGR tube, and intake and exhaust manifolds for carbon build-up and repair as necessary. Retest EGR system.
NOTE: A break in test sequence occurs at this point. Sequence skips from TEST TC-46A to TEST TC-48A. No tests have been omitted.
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