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DTC P1491: Rad Fan Control Relay Circuit

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For circuit identification and wiring diagram, see CHEROKEE wiring diagram in WIRING DIAGRAMS article.
NOTE: DTC P1491: RAD FAN CONTROL RELAY CIRCUIT is monitored with ignition on and battery voltage more than 10.4 volts. DTC may be stored in Powertrain Control Module (PCM) if PCM senses open or shorted condition in radiator fan relay control circuit. Possible causes are: defective radiator fan control relay, defective PCM, defective connector or defective wiring.
  1. Turn ignition on, with engine off. Using scan tool, actuate radiator fan relay. Radiator fan relay is located in Power Distribution Center (PDC). PDC is located next to battery. Refer to label under PDC cover for relay location. If radiator fan relay clicks, go to next step. If radiator fan relay does not click, go to step 4).
  2. Ensure ignition is on, with engine off. Wiggle wiring harness from radiator fan relay to PCM while actuating radiator fan relay. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. If radiator fan relay stops clicking at any time while wiggling wiring harness, repair wiring harness where wiggling caused radiator fan relay to stop clicking. Perform TEST VER-5A. If radiator fan relay does not stop clicking at any time while wiggling wiring harness, go to next step.
  3. Turn ignition off. Visually inspect related connectors and wiring harness. Repair connectors and wiring harness as necessary. Perform TEST VER-5A. If connectors and wiring harness are okay, test is complete.
  4. Turn ignition off. Remove radiator fan relay. Radiator fan relay is located in Power Distribution Center (PDC). PDC is located next to battery. Refer to label under PDC cover for relay location. Clean and/or repair connector as necessary. Using an ohmmeter, check resistance between radiator fan relay terminals No. 85 and 86. See Figure. If resistance is less than 100 ohms, go to next step. If resistance is 100 ohms or more, replace radiator fan relay. Perform TEST VER-5A.
  5. Ensure ignition is off. Ensure radiator fan relay is still removed. Turn ignition on, with engine off. Using a voltmeter connected to ground, probe radiator fan relay connector, fused ignition switch output circuit (White wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open fused ignition switch output circuit. Perform TEST VER-5A.
  6. Ensure ignition is off. Ensure radiator fan relay is still removed. Disconnect PCM Gray connector. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. Clean and/or repair connector as necessary. Using an ohmmeter, check resistance between ground and PCM connector, radiator fan relay control circuit (Dark Blue/Pink wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair radiator fan relay control circuit for short to ground. Perform TEST VER-5A.
  7. Ensure ignition is off. Ensure radiator fan relay and PCM connectors are still disconnected. Using ohmmeter, check resistance of radiator fan relay control circuit (Dark Blue/Pink wire) between radiator fan relay and PCM. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open radiator fan relay control circuit. Perform TEST VER-5A.
  8. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-5A.
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