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Power & Ground Circuits (Altima)

  1. Start engine. If engine starts, go to step  6. If engine does not start, turn ignition off and on. Measure voltage between ground and ECM harness connector terminal No. 38 (Red wire) by backprobing. For ECM location, see Fig 1. For ECM terminal identification, see Fig 2. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See WIRING DIAGRAMS article.
  2. Turn ignition off. Disconnect ECM harness connector. Check continuity between ground and ECM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118 (Black wires). See Fig 2. If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in affected wire. See WIRING DIAGRAMS article.
  3. Disconnect ECM relay harness connector located near ECM. Measure voltage between ground and ECM relay harness connector terminals No. 1 and 3 (White/Blue wires). See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See WIRING DIAGRAMS article.
  4. Turn ignition off. Check continuity of White/Green wire between ECM harness connector terminal No. 4 and ECM relay harness connector terminal No. 2. See Fig 2 and Figure . Also, check circuit for short to ground and short to voltage. Repair circuit as necessary. If circuit is okay, go to next step.
  5. Reconnect all harness connectors. Check fuel injectors and circuits. See FUEL CONTROL  under FUEL SYSTEM. Repair as necessary. If no problems are found, go to next step.
  6. Measure voltage between ground and ECM harness connector terminals No. 70 and 113 (White/Blue wires) by backprobing. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See WIRING DIAGRAMS article.
  7. While turning ignition on then off, measure voltage between ground and ECM harness connector terminals No. 56 and 61 (White/Red wires) by backprobing. Battery voltage should exist for a few seconds after ignition is turned off, then drop to about zero volts. If voltage is as specified, go to step  13. If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds after ignition is turned off, go to step  12.
  8. Turn ignition off. Disconnect ECM harness connector. Disconnect ECM relay harness connector located near ECM. Check continuity of White/Red wires between ECM relay harness connector terminal No. 5 and ECM harness connector terminals No. 56 and 61. See Fig 2 and Figure . Also, check circuit for short to ground and short to voltage. Repair circuit as necessary. If circuit is okay, go to next step.
  9. Measure voltage between ground and ECM relay harness connector terminals No. 1 and 3 (White/Blue wires). See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See WIRING DIAGRAMS article.
  10. Turn ignition off. Check continuity of White/Green wire between ECM harness connector terminal No. 4 and ECM relay harness connector terminal No. 2. See Fig 2 and Figure . Also, check circuit for short to ground and short to voltage. Repair circuit as necessary. If circuit is okay, go to next step.
  11. Check continuity of White/Blue wire between ECM harness connector terminal No. 113 and ECM relay harness connector terminals No. 1 and 3. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary. If circuit is okay, go to next step.
  12. Check ECM relay. See RELAYS  under RELAYS & SOLENOIDS. Replace, if necessary and retest system. If relay is okay, go to next step.
  13. Turn ignition off. Disconnect ECM harness connector. Check continuity between ground and ECM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118 (Black wires). See Fig 2. Also, check circuits for short to voltage. Repair circuit(s) as necessary. If all circuits are okay, go to next step.
  14. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Locating ECM Harness Connector (Altima)
G98F01295Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Identifying ECM Connector Terminals (Altima)
G95C31502Courtesy of NISSAN MOTOR CO., U.S.A.
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