LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Dodge and Ram >> 2001 >> Durango 5.9 Z, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1491: Rad Fan Control Relay Circuit >> Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P1491: Rad Fan Control Relay Circuit: Testing

  1. Turn ignition on. Using scan tool, actuate RADIATOR FAN RELAY. Check radiator fan operation. 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 on and radiator fan control relay is still actuated. Wiggle wiring harness and connectors between radiator fan control relay and PCM while observing operation of radiator fan. Radiator fan relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. See Figure. PCM is located in engine compartment on passenger-side inner fender panel. If radiator fan operation was not interrupted while wiggling wiring harness and connectors, go to next step. If radiator fan operation was interrupted while wiggling wiring harness and connectors, repair wiring harness as necessary where wiggling caused radiator fan operation to be interrupted.
  3. Turn ignition off. Inspect wiring and connectors between radiator fan relay and PCM. If any problems exist, repair wiring or connectors as necessary. If no problems exist, test is complete.
  4. Turn ignition off. Remove radiator fan relay from PDC. Radiator fan relay is located in Power Distribution Center (PDC). PDC is located in engine compartment, next to battery. See Figure. Disconnect PCM connectors. PCM is located in engine compartment on passenger-side inner fender panel. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Pink wire between radiator fan relay cavity terminal No. 85 and PCM harness connector C2 terminal No. 17. See Figure and Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Pink wire between radiator fan relay and PCM.
  5. Ensure ignition is off, radiator fan relay is removed from PDC and PCM is disconnected. Measure resistance between ground and PCM harness connector C2 terminal No. 17 (Dark Blue/Pink wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Pink wire between radiator fan relay and PCM.
  6. Ensure ignition is off and PCM is disconnected. Reinstall radiator fan relay into PDC. Connect one end of a jumper wire to PCM harness connector C2 terminal No. 17 (Dark Blue/Pink wire). See Figure. Turn ignition on. Briefly tap other end of jumper wire to ground and observe radiator fan operation. If radiator fan turns on, go to next step. If radiator fan does not turn on, replace radiator fan relay.
  7. At this time, PCM is assumed to be defective. Replace PCM.
scientia non olet · About LEMON Manuals