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Home >> Nissan-Datsun >> 1995 >> Quest XE >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests 3.0L >> Miscellaneous Controls >> Radiator (Cooling) Fan High Speed Control Test

Radiator (Cooling) Fan High Speed Control Test

  1. Turn ignition off. Disconnect radiator fan high-speed (No. 2) relay. See Figure . Turn ignition on. Measure voltage between ground and radiator fan high-speed (No. 2) relay harness connector terminals No. 2 and No. 3 (Blue/Yellow wires). 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. Check 10-amp fuse located in fuse box under left instrument panel. Replace fuse as necessary. Check 120-amp and 65-amp fusible link located in fusible link and fuse box next to battery. Replace fusible link(s) as necessary. If fuse and fusible links are okay, repair open harness or connectors.
  3. Turn ignition off. Disconnect radiator fan high-speed (No. 3) relay. Check continuity between radiator fan relay No. 2 harness connector terminal No. 2 (Blue wire) and radiator fan relay No. 3 harness connector terminal No. 2 (Blue wire). See Fig 1 .
  4. Also check continuity between radiator fan relay No. 2 harness connector terminals No. 3 (Blue/Yellow wire) and radiator fan relay No. 3 harness connector terminals No. 3 (Blue/Yellow wire). Continuity should exist in all checks. If continuity exists in all checks, go to next step. If continuity does not exist in any check, repair open harness or connector.
  5. Disconnect radiator fan motor harness connector. Check continuity between radiator fan motor harness connector terminal "a" (Blue/Red wire) and radiator fan relay No. 2 harness connector terminal No. 5 (Blue/Red wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Blue/Red wire or connectors.
  6. Check continuity between radiator fan relay No. 2 harness connector terminal No. 5 (Blue/Red wire) and radiator fan relay No. 3 harness connector terminal No. 5 (Blue/Red wire). See Fig 1 . Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Blue/Red wire or connectors.
  7. Disconnect ECM harness connector. ECM is located behind glove box. Check continuity between ECM harness connector terminal No. 10 (Brown/White wire) and radiator fan relay No. 2 harness connector terminal No. 1 (Brown/White wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Brown/White wire or connectors between ECM and relay.
  8. Check continuity between radiator fan relay No. 2 harness connector terminal No. 1 (Brown/White wire) and radiator fan relay No. 3 harness connector terminal No. 1 (Brown/White wire). Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Brown/White wire or connectors.
  9. Check radiator fan relays No. 2 and No. 3. See RELAYS  under RELAYS & SOLENOIDS. Replace relay(s) as necessary. If relays are okay, check fan motor(s). See RADIATOR FAN MOTOR TEST  . Replace motor(s) as necessary. If fan motors are okay, check ECM terminals, harness, and connector terminals for damage, corrosion or improper connection. Repair or replace as necessary.
  10. If vehicle is A/C equipped, disconnect high-pressure switch harness connector. Check continuity between ground and high-pressure switch harness connector Black wire terminal. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Black wire or connectors.
  11. Disconnect ECM harness connector. ECM is located behind glove box. Check continuity between ECM harness connector terminal No. 45 (Blue/Black wire) and high-pressure switch harness connector Blue/Black wire terminal. Continuity should exist. If continuity exists, go to next step. If continuity does not exist, repair open Blue/Black wire or connectors.
  12. Reconnect all disconnected relays and connectors. With engine running and A/C system on, check continuity between high-pressure switch terminals. With high pressure increasing to 326 psi (22.9 kg/cm2 ), no continuity should exist (fan off). With high pressure decreasing to 264 psi (18.6 kg/cm2 ), continuity should exist (fan on).
  13. If continuity is not as specified, replace high pressure switch. If continuity is as specified, check ECM terminals, harness, and connector terminals for damage, corrosion or improper connection. Repair or replace as necessary.
Fig 1: Testing Radiator Fan High Speed Circuit
G93D80229Courtesy of NISSAN MOTOR CO., U.S.A.
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