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DTC P1490: Low Speed Fan Control Relay Circuit

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION  . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Monitored with ignition in RUN position and battery voltage more than 10 volts. Set condition is when an open or shorted condition is detected in low speed fan relay control circuit. Possible causes are: ignition switch output circuit open, low speed fan relay defective, intermittent wiring harness failure, low speed fan relay control circuit open, low speed fan relay control circuit short to ground or PCM defective.
  1. Turn ignition on with engine off. Using scan tool, actuate low speed fan relay. Low speed fan relay is located in Power Distribution Center (PDC) at driver's side front corner of engine compartment, just in front of strut tower. If relay is clicking, go to next step. If relay is not clicking, go to step  4 .
  2. Turn ignition off. Inspect wiring and connectors for damage. If wiring and connectors are okay, test is complete. If wiring and connectors are not okay, repair or replace as necessary. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  3. Turn ignition on with engine off. Using scan tool, actuate high speed fan relay. Wiggle wiring harness between high speed fan relay connector and Powertrain Control Module (PCM) connector. If wiggling interrupted relay actuation, repair wiring harness as necessary where wiggling caused problem to appear. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  . If wiggling did not interrupt relay actuation, test is complete.
  4. Turn ignition off. Disconnect low speed fan relay. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of low speed fan relay. See Fig 1 . If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, replace low speed fan relay. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
    Fig 1: Testing Relay
    G94C31759Courtesy of CHRYSLER CORP.
  5. Turn ignition on with engine off. Using DVOM, check voltage of low speed fan relay connector terminal No. 84 ignition switch output circuit (Light Green/Black wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open ignition switch output circuit. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  6. Disconnect Powertrain Control Module (PCM) connector C2 (located nearest to rear of vehicle). PCM is located to left of Power Distribution Center (PDC) in engine compartment. Inspect electrical connector and clean/repair as necessary. Using a DVOM, check resistance of low speed fan relay control circuit between low speed fan relay connector terminal No. 86 (Dark Blue/Tan wire) and PCM connector C2 terminal No. 55 (Dark Blue/Tan wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open low speed fan relay control circuit. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II 
  7. Using a DVOM, check resistance of low speed fan relay control circuit between PCM connector C2 terminal No. 55 (Dark Blue/Tan wire) and chassis ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair low speed fan relay control circuit short to ground. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
  8. Turn ignition off. If no other potential causes are remaining, PCM is assumed to be defective. Replace PCM. Perform TEST VER-2A: ROAD TEST FOR NON-OBD II  .
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