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Power & Ground Circuits (Sentra 1.8L)

  1. Start engine. If engine starts, go to next step. If engine does not start, turn ignition off and on. Measure voltage between ground and ECM terminal No. 43 (Black/Red wire) by backprobing. See Figure and Fig 1 . If battery voltage exists, go to step  8. If battery voltage does not exist, repair open or short circuit between ECM and fuse block. See WIRING DIAGRAMS article.
  2. Turn ignition off. Measure voltage between ground and ECM terminal No. 67 (White/Blue wire) by backprobing. See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, repair short or open circuit between ECM and fuse block. See WIRING DIAGRAMS article.
  3. While turning ignition on and off, measure voltage between ground and ECM terminals No. 110 and 112 (White wires) by backprobing. Battery voltage should exist for a few seconds after turning ignition off. If voltage is as specified, go to step  8. If battery voltage does not exist, go to next step. If battery voltage exists for more than a few seconds, go to step  7.
  4. Turn ignition off. Remove ECM relay. See Fig 2. Disconnect ECM harness connector. Check continuity of White wire between ECM harness connector terminals No. 110 and 112 and ECM relay harness connector terminal No. 5. See Figure 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. Measure voltage between ground and ECM relay harness connector terminals No. 1 and 3 (White/Blue wires). If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See WIRING DIAGRAMS article.
  6. Turn ignition off. Check continuity of White/Green wire between ECM relay harness connector terminal No. 2 and ECM harness connector terminal No. 31. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary. If circuit is okay, go to next step.
  7. Check ECM relay. See RELAYS  under RELAYS & SOLENOIDS. Replace, if necessary and retest system. If relay is okay, go to next step.
  8. Turn ignition off. Disconnect ECM harness connector. Check continuity between ground and ECM harness connector terminals No. 48 and 57 (Black wires) and terminals No. 106 and 108 (Black/Yellow wires). Continuity should exist. Also, check circuits for short to voltage. Repair circuit(s) as necessary. If circuits are okay, go to next step.
  9. 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 (Sentra)
G00051968Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Locating ECM Relay (Sentra)
G00051958Courtesy of NISSAN MOTOR CO., U.S.A.
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