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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 33 (Engine Controls - Tests W/Codes - 3.8L) >> Self-Diagnostic Tests >> Test TC-25A - EGR System Failure (DTC 32)

Test TC-25A - EGR System Failure (DTC 32)

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, 1995 Dodge Caravan, and 1995 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS  section at the end of this article.
  1. Start engine. Allow engine to idle for at least 2 minutes. Disconnect vacuum supply hose from Exhaust Gas Recirculation (EGR) solenoid. Connect a vacuum gauge to end of disconnected hose. If vacuum gauge indicates less than 10 in. Hg, repair vacuum supply to EGR solenoid. Perform TEST VER-2.
  2. If vacuum gauge indicates more than 10 in. Hg, reconnect vacuum hose to EGR solenoid. Disconnect vacuum hose from EGR valve. Connect a vacuum gauge to end of disconnected hose. While observing vacuum gauge, momentarily raise engine speed to more than 2000 RPM.
  3. If vacuum gauge indicates less than 5 in. Hg while throttle is opened, replace EGR valve assembly. Perform TEST VER-2. If vacuum gauge indicates more than 5 in. Hg while throttle is opened, remove vacuum gauge.
  4. Connect a vacuum pump to EGR valve. With engine idling, slowly apply vacuum to EGR valve. If engine idle becomes rough as vacuum is applied, go to next step. If engine idle does not become rough, remove EGR valve and inspect manifold and EGR backpressure tube for restrictions. If restrictions are present, clean as necessary. Perform TEST VER-2. If no restrictions are present, replace EGR valve assembly. Perform TEST VER-2.
  5. Turn ignition off. Apply vacuum to EGR valve. Observe vacuum gauge. If vacuum is not held for at least 10 seconds, replace EGR valve assembly. Perform TEST VER-2.
  6. If vacuum is held for at least 10 seconds, condition required to set DTC is not present at this time. EGR SYSTEM FAILURE DTC sets when Powertrain Control Module (PCM) performs a test of EGR system and does not detect any change in Oxygen Sensor (O2S) signal. Possible causes are: EGR valve not opening, EGR backpressure tube blocked or EGR passages in manifold blocked. Go to next step.
  7. Inspect all related vacuum hoses and connectors, and repair as necessary. Perform TEST VER-2. If no problems are found with vacuum hoses and connectors, see INACTIVE DTC CONDITION  .
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