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DTC P1491: EGR Valve Lift Insufficient Detected

  1. Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES  under SELF-DIAGNOSTIC SYSTEM. Connect SCS Service Connector (07PAZ-0010100 ) to 2-pin service check connector located under passenger side of instrument panel. See Figure. Start engine and hold at 3000 RPM with no load and transmission in Park or Neutral, until cooling fan comes on. Test drive vehicle for approximately 10 minutes with engine speed at 1700-2500 RPM. If DTC P1491 resets, go to next step. If DTC P1491 does not reset, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at EGR valve, harness connector located at right shock tower and PCM connectors.
  2. Start engine and allow to idle. Backprobing, measure voltage between EGR valve 6-pin connector terminals No. 4 (Pink wire) and No. 6 (Black wire). If battery voltage does not exist, go to next step. If battery voltage exists, substitute a known-good PCM and recheck. If DTCs do not reset, replace original PCM.
  3. Turn ignition off. Disconnect EGR valve 6-pin connector. Connect a fused jumper wire between positive battery terminal and EGR valve 6-pin connector terminal No. 4 (Pink wire). Connect a fused jumper wire to EGR valve 6-pin connector terminal No. 6 (Black wire). Start engine and let it idle. Connect second fused jumper to negative battery terminal. If engine stalls or runs rough, go to next step. If engine does not stall or run rough, replace EGR valve.
  4. Turn ignition off. Disconnect PCM 25-pin connector. Check for continuity between PCM harness connector terminal No. 7 (Pink wire) and EGR valve 6-pin harness connector terminal No. 4 (Pink wire). If continuity exists, go to next step. If continuity does not exist, repair open in Pink wire between EGR vales 6-pin connector and PCM 25-pin connector.
  5. Check for continuity between ground and EGR valve 6-pin harness connector terminal No. 6 (Black wire). If continuity does not exist, repair open in Black wire between EGR valve 6-pin connector and ground terminal G101 located at right rear of engine next to IAT sensor. If continuity exists, substitute a known-good PCM and recheck. If DTCs do not reset, replace original PCM.
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