2002 Nissan-Datsun Sentra SE-R, AutomaticFACTORY OEM SERVICE PROCEDURE

Power & Ground Circuits (Sentra 1.8L)

  1. Start engine. If engine starts, go to step  4. If engine does not start, go to next step.
  2. Turn ignition off, and then on. Backprobing at ECM, measure voltage between ground and ECM terminal No. 43 (Black/Red wire). See Figure and Figure . If battery voltage exists, go to step  13. If battery voltage does not exist, go to next step.
  3. Check following:
    • Check fuse block fuse No. 17 (10-amp).
    • Check for poor, loose, corroded or damaged terminal connections in fuse block junction block harness connector M1. See WIRING DIAGRAMS article.
    • Check for poor, loose, corroded or damaged terminal connections in in-line harness connectors E9 and F47.
    • Check for poor, loose, corroded or damaged terminal connections in in-line harness connectors M19 and E108.
    • Check for open or short in circuits between ECM and fuse.
    If problem is found, repair as necessary. After repair, retest system.
  4. Turn ignition off. Backprobing at ECM, measure voltage between ground and ECM terminal No. 67 (White/Blue wire). See Figure. If battery voltage does not exist, go to next step. If battery voltage exists, go to step  6.
  5. Check following:
    • Check fuse block fuse No. 17 (10-amp).
    • Check for poor, loose, corroded or damaged terminal connections in fuse block junction block harness connector E24. See WIRING DIAGRAMS article.
    • Check for poor, loose, corroded or damaged terminal connections in in-line harness connectors E9 and F47.
    • Check for open or short in circuits between ECM and fuse.
    If problem is found, repair as necessary. After repair, retest system.
  6. Turn ignition on, and then off. Backprobing at ECM, measure voltage between ground and ECM terminals No. 110 and 112 (White wires). See Figure. Battery voltage should exist at each terminal for a few seconds after turning ignition off. 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, go to step  12.
  7. Turn ignition off. Disconnect ECM 116-pin harness connector. For ECM location, see Figure. Remove ECM relay from fuse and relay panel. For ECM relay location, see Fig 1. Check continuity of White wires between ECM harness connector terminals No. 110 and 112 and ECM relay harness connector terminal No. 5. See Figure and Figure . Continuity should exist. Also, check circuit for short to ground and short to voltage. If no problem is found, leave relay and harness connector disconnected and go to next step. If problem is found, repair circuit as necessary. After repair, retest system.
  8. Measure voltage between ground and ECM relay harness connector terminals No. 1 and 3 (White/Blue wires). If battery voltage does not exist, go to next step. If battery voltage exists, leave relay and harness connector disconnected and go to step  10.
  9. Check for open or short in circuits between ECM relay and fuse. See WIRING DIAGRAMS article. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, retest system.
  10. Check continuity in White/Green wire between ECM harness connector terminal No. 31 and ECM relay harness connector terminal No. 2. Continuity should exist. Also, check circuits for short to ground or short to voltage. If problem is found, go to next step. If no problem is found, go to step  12.
  11. Check for open or short in circuits between ECM relay and ECM. See WIRING DIAGRAMS article. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, retest system.
  12. Working with ECM relay, apply battery voltage and ground to terminals No. 1 and 2. See Figure. When battery voltage is applied, continuity should exist between terminals No. 3, 5, 6 and 7. When battery voltage is removed, continuity should not exist. If relay tests okay, go to next step. Replace relay, if test values are not as specified.
  13. Turn ignition off. Disconnect ECM 116-pin harness connector. For ECM location, see Figure. Check continuity between engine ground and ECM harness connector terminals No. 48 and 57 (Black wires) and No. 106 and 108 (Black/Yellow wires). Continuity should exist. Also, check circuits for short to voltage. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, retest system.
  14. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
Fig 1: Locating Engine Control Module Relay (Sentra 1.8L)
G00051958Courtesy of NISSAN MOTOR CO., U.S.A.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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