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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: Radiator fan control relay circuit is monitored when ignition is on, battery voltage is more than 10 volts. DTC may be stored in PCM if an open or shorted condition is detected in low speed radiator fan control relay circuit. Possible causes are: defective radiator fan control relay, defective radiator fan, defective PCM, or defective connectors or wiring.
  1. Turn ignition on with engine off. Using scan tool, actuate radiator fan control relay. 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. Turn ignition on with engine off. Using scan tool, actuate radiator fan control relay. Wiggle wiring harness and connectors from radiator fan control relay to the PCM while noting operation of radiator fan. Radiator fan control relay is located in Power Distribution Center (PDC). See Figure. PCM is located in engine compartment, between air cleaner and radiator. 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-2A .
  3. Turn ignition off. Inspect wiring and connectors between radiator fan control 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-2A .
  4. Turn ignition off. Disconnect radiator fan control relay. Radiator fan control relay is located in Power Distribution Center (PDC). See Figure. Using test light, check for voltage at radiator fan control relay cavity No. 73 (Gray wire). If test light illuminates brightly, go to next step. If test light does not illuminate brightly, repair high resistance or open on Gray wire between radiator fan control relay cavity No. 73 and fuse No. 6 in PDC. Perform TEST VER-2A .
  5. Ensure ignition is off. Disconnect PCM connectors. PCM is located in engine compartment, between air cleaner and radiator. Using ohmmeter, check resistance of Dark Blue/Pink wire between radiator fan control relay cavity No. 70 and PCM connector terminal No. 55. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit on Dark Blue/Pink wire between PCM and radiator fan control relay in PDC. Perform TEST VER-2A .
  6. Check resistance between ground and PCM connector terminal No. 55 (Dark Blue/Pink wire). If resistance is less than 5 ohms, repair short to ground on Dark Blue/Pink wire between PCM and radiator fan control relay in PDC. Perform TEST VER-2A . If resistance is 5 ohms or more, go to next step.
  7. Reinstall radiator fan control relay in PDC. Ensure PCM connectors are still disconnected. Connect one end of a jumper wire to PCM connector terminal No. 55 (Dark Blue/Pink wire). Momentarily touch other end of jumper wire to ground. If radiator fan actuates, replace PCM. Perform TEST VER-2A . If radiator fan does not actuate, replace radiator fan control relay. Perform TEST VER-2A .
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