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Powertrain Control Module (Pcm): 240SX

  1. Start engine. If engine starts, go to step 6). If engine does not start, go to next step.
  2. Turn engine off and leave ignition on. Using DVOM, measure voltage between PCM harness connector terminal No. 38 (Black/Red wire) and ground by backprobing connector. See Figure. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in Black/Red wire between fuse block and PCM.
  3. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. See Figure. If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
  4. Disconnect ECCS relay (located behind PCM). Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5. See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
  5. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1 (Red/Black wire). See Figure & Figure . If continuity exists, go to next step. If continuity does not exist, repair open or short in Red/Black wire.
  6. Turn ignition on. Using DVOM, measure voltage between ground and PCM harness connector terminals No. 70 and 113 (Red wire) by backprobing connector. If battery voltage is present, go to next step. If battery voltage is not present, repair blown fuse or open or short in appropriate Red wire between fuse block and PCM.
  7. Turn ignition off. While turning ignition on then off, measure voltage between ground and PCM harness connector terminals No. 56 and 61 by backprobing connector. Battery voltage should exist with ignition on and for a few seconds after ignition is turned off. If voltage is as specified, go to step 12). 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 11).
  8. Turn ignition off. Disconnect PCM harness connector. Disconnect ECCS relay (located under PCM). Using DVOM, check continuity between ECCS harness connector terminal No. 3 and PCM harness connector terminals No. 56 and 61. See Figure & Figure . If continuity exists on both wires, go to next step. If continuity does not exist on either wire, repair open or short in appropriate wire. See WIRING DIAGRAMS article.
  9. Turn ignition on. Using DVOM, measure voltage between ground and ECCS relay harness connector terminals No. 2 and 5. See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, repair blown fuse or open or short in appropriate wire.
  10. Turn ignition off. Check continuity between PCM harness connector terminal No. 4 and ECCS relay harness connector terminal No. 1. See Figure & Figure . If continuity exists, go to next step. If continuity does not exist, repair open or short in Red/Black wire.
  11. Check ECCS relay. See RELAYS  under RELAYS & SOLENOIDS. If continuity is as specified, go to next step. If continuity is not as specified, replace ECCS relay and retest system.
  12. Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity between ground and PCM harness connector terminals No. 10, 19, 39, 43, 106, 112 and 118. See Figure. If continuity exists on all wires, go to next step. If continuity does not exist on any wire, repair open in appropriate wire. See WIRING DIAGRAMS article.
  13. Check PCM harness connector terminals for damage or corrosion. Repair as necessary, reconnect all connectors and retest system.
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