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ECM Power & Ground Circuits

  1. Start engine. If engine is running, go to next step. If engine will not start, turn ignition on. Measure voltage between ground and ECM harness connector terminal No. 36 (Black/Yellow wire).Battery voltage should be present. If battery voltage is present, go to step 7). If battery voltage is not present, repair open in Black/Yellow wire (1.6L) or Black/Red wire (2.0L) between ECM harness connector and ignition switch.
  2. Turn ignition off. Measure voltage between ground and ECM harness connector terminals No. 46 (White wire) and No. 109 (Orange/Blue wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check harness and connectors between ECM and battery. Check 25-amp fusible link.
  3. Turn ignition on and off while measuring voltage between ground and ECM harness connector terminals No. 38 (Orange/Blue wire) and No. 47 (Orange/Blue wire). With ignition on and for a few seconds after turning ignition off, battery voltage should be present. A few seconds after turning ignition off, approximately zero volts should be present. If voltage is as specified, go to step 7). If battery voltage exists for more than a few seconds, check ECM relay. ECM relay is located next to ECM. See RELAYS  under RELAYS & SOLENOIDS.
  4. If battery voltage does not exist for a few seconds, disconnect ECM harness connector. Disconnect ECM relay. Check continuity between ECM harness connector terminals No. 38 (Orange/Blue wire) and No. 47 (Orange/Blue wire) and ECM relay harness connector terminal No. 5 (Orange/Blue wire). See Figure . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open in Orange/Blue wire.
  5. Measure voltage between ground and ECM relay harness connector terminals No. 1 (White wire) and No. 3 (White wire). See Figure . Battery voltage should exist. If battery voltage exists, go to next step. If battery voltage does not exist, check harness and connectors.
  6. Check continuity between ECM harness connector terminal No. 4 (White/Green wire) and ECM relay harness connector terminal No. 2 (White/Green wire). See Figure . Continuity should exist. If continuity exists. check ECM relay. See RELAYS  under RELAYS & SOLENOIDS. If relay is okay, go to next step. If continuity does not exist, repair harness or connectors.
  7. Turn ignition off. With ECM harness connector disconnected, check continuity between ground and ECM harness connector terminals No. 6, 13, 39, 48, 107, 108 and 116 (all wires are Black). Continuity should exist. If continuity exists, check ECM pin terminals and ECM harness connector terminals for damage or corrosion. If continuity does not exist, repair harness or connectors.
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