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Power & Ground Circuits (Frontier & Xterra)

  1. Start engine. If engine starts, turn engine off and go to next step. If engine does not start, turn ignition off and on. Measure voltage between ground and PCM harness connector terminal No. 24 (White/Green wire on 4-cylinder models, or White/Blue wire on V6 models) by backprobing. See Fig 1 and Fig 2 . If battery voltage exists, go to step  8. If battery voltage does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  2. Measure voltage between ground and PCM harness connector terminal No. 80 (Light Blue wire) by backprobing. See Fig 2. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
    Fig 1: Locating PCM & PCM Harness Connector (Frontier & Xterra)
    G98J01320Courtesy of NISSAN MOTOR CO., U.S.A.
  3. While turning ignition on and off, measure voltage between ground and PCM harness connector terminals No. 67, 72 and 117 (Black/Pink 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. Disconnect PCM harness connector. Disconnect ECCS relay harness connector, located near PCM. Check continuity of Black/Pink wires between ECCS relay harness connector terminal No. 3 and PCM harness connector terminals No. 67, 72 and 117. See Fig 2 and Figure . If continuity exists, go to next step. If continuity does not exist, repair open in Black/Pink wire(s).
  5. Measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5 (Light Blue wires). See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  6. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1 (Light Green/Red wire on 4-cylinder models, or Orange/Black wire on V6 models). See Fig 2 and Figure . If continuity exists, go to next step. If continuity does not exist, repair open circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  7. Check ECCS 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 PCM harness connector. Check continuity between ground and PCM harness connector terminals No. 10, 19, 116 and 124 (Black/Red wires) and terminals No. 25 and 32 (Black/Yellow wires). See Fig 2. If continuity exists, go to next step. If continuity does not exist, repair open ground circuit(s).
  9. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article.
Fig 2: Identifying PCM Harness Connector Terminals (Frontier, Pathfinder, Quest & Xterra)
G96H10790Courtesy of NISSAN MOTOR CO., U.S.A.
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