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DTC P1609: Internal ECM Error

  1. On XK8, if DTC P1609 is present, replace ECM. On XJ Series, turn ignition off. Disconnect ECM harness connector EM11. Measure resistance between ECM harness connector EM11 terminal No. 3 (Purple wire) and ground point G121. See Figure. See WIRING DIAGRAMS article. If resistance is more than 10 megohms, go to next step. If resistance is 10 megohms or less, repair short to ground and retest system.
  2. Disconnect ECM harness connector EM13. Measure resistance between ECM harness connector EM13 terminal No. 1 (Pink/Brown wire) and ground point G121. If resistance is more than 10 megohms, go to next step. If resistance is 10 megohms or less, repair short to ground and retest system.
  3. Allow engine to cool and perform a drive cycle. Drive cycle must include idling, quick acceleration and cruising, while engine is warming up to and including normal operating temperature. Check for DTCs. If DTC P1609 is present, replace ECM. If DTC P1609 is not present, system is okay.
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