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DTC P1491: Rad Fan Control Relay Circuit

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION  . For wiring diagram, see WIRING DIAGRAMS article.
NOTE: Radiator fan control relay is referred to as radiator fan relay in test procedures. Radiator fan relay control circuit is monitored when ignition is on, battery voltage is more than 10 volts and Powertrain Control Module (PCM) requests radiator fan to be turned on. DTC may be stored in PCM if an open or shorted condition is detected in radiator fan relay control circuit. Possible causes are: defective radiator fan relay, defective PCM, or defective connectors or wiring.
  1. Turn ignition on with engine off. Using scan tool, actuate radiator fan control. If radiator fan cycles on and off, go to next step. If radiator fan does not cycle on and off, go to step  4 .
  2. Ensure ignition is still on and radiator fan control is still actuated. Wiggle wiring harness and connectors from radiator fan relay to PCM while noting operation of radiator fan. Radiator fan relay is located in power distribution center at driver's side front corner of engine compartment, near battery. See Figure . PCM is located at passenger's side front corner of engine compartment on inner fender panel. If cycling of radiator fan was not interrupted while wiggling wiring harness and connectors, go to next step. If cycling of radiator fan was interrupted while wiggling wiring harness and connectors, repair wiring or connectors as necessary. Perform TEST VER-2  .
  3. Turn ignition off. Inspect wiring harness and connectors between radiator fan relay, PCM and radiator fan. If no problems exist, test is complete. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-2  .
  4. Turn ignition off. Remove radiator fan relay from power distribution center at driver's side front corner of engine compartment, near battery. See Figure . Turn ignition on with engine off. Note cavities in power distribution center for radiator fan relay. See Figure . Using voltmeter, check voltage at cavity No. 86 (Light Green/Black wire) in power distribution center for radiator fan relay. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open between ignition switch, fuse No. 9 (10-amp) and Light Green/Black wire between fuse No. 9 and cavity No. 86 in power distribution center for radiator fan relay. Fuse No. 9 is located in junction block on end of driver's side of instrument panel, near door opening. Perform TEST VER-2  .
  5. Turn ignition off. Ensure radiator fan relay is removed from power distribution center. Disconnect PCM connectors. PCM is located at passenger's side front corner of engine compartment on inner fender panel. Using ohmmeter, check resistance between cavity No. 85 (Dark Blue/Pink wire) in power distribution center for radiator fan relay and terminal No. 17 (Dark Blue/Pink wire) on PCM connector C2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Dark Blue/Pink wire between PCM and cavity No. 85 in power distribution center for radiator fan relay. Perform TEST VER-2  .
  6. Ensure radiator fan relay is removed from power distribution center. Using ohmmeter, check resistance between ground and terminal No. 17 (Dark Blue/Pink wire) on PCM connector C2. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-2  . If resistance is less than 5 ohms, repair short to ground on Dark Blue/Pink wire between PCM and cavity No. 85 in power distribution center for radiator fan relay. Perform TEST VER-2  .
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