1993 Nissan-Datsun Sentra SE-R, AutomaticFACTORY OEM SERVICE PROCEDURE

ECM Power & Ground Circuits (ALTIMA)

  1. Turn ignition on. Measure voltage between ground and ECM harness connector terminals No. 38 (Orange wire) and No. 47 (Orange wire). See Figure and Figure . ECM is located under center of instrument panel (connector is on passenger's side). Battery voltage should be present. If battery voltage is present, go to step 3). If battery voltage is not present, go to next step.
  2. Turn ignition off. Disconnect ECM harness connector. Check continuity between ground and ECM harness connector terminals No. 6 (Black wire), No. 13 (Black wire), No. 107 (Black wire), No. 108 (Black wire) and No. 116 (Black wire). See Figure and Figure . Continuity should exist. If continuity does not exist, repair harness or connectors. If continuity exists, check ECM pin terminals for damage or connection of ECM harness connector.
  3. Turn ignition off. Disconnect ECM harness connector. Disconnect ECM relay. ECM relay is located next to ECM. Check continuity between ECM relay harness connector Orange wire (terminal No. 3) and ECM harness connector terminals No. 38 (Orange wire) and No. 47 (Orange wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair harness or connectors.
  4. Measure voltage between ground and ECM relay harness connector White wire (terminals No. 1 and 5). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check for open in harness or connectors. Check 25-amp fusible link. Check continuity between ECM relay harness connector White wire and battery.
  5. Measure voltage between ground and ECM harness connector terminal No. 46 (White wire). Battery voltage should be present. If battery voltage is present, go to next step. If battery voltage is not present, check for open in harness or connectors. Check 25-amp fusible link. Check continuity between ECM relay harness connector White wire and battery.
  6. Check continuity between ground and ECM harness connector terminals No. 39 (Black wire) and No. 48 (Black wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair harness or connectors.
  7. Check continuity between ECM harness connector terminal No. 4 (White/Green wire) and ECM relay harness connector White/Green wire (terminal No. 2). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair harness or connectors.
  8. Turn ignition on. Measure voltage between ground and ECM harness connector terminal No. 36 (Black/Red wire). Battery voltage should be present. If battery voltage is present, check ECM relay. See RELAYS under RELAYS & SOLENOIDS  . If relay is okay, check ECM pin terminals and ECM harness connector terminals for damage or corrosion. If battery voltage is not present, check harness and connectors. Check continuity of Red/Black wire between ECM harness connector and ignition switch.
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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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