Skip to content
GTECH Calibration
Portal

P1491

Radiator Fan Control Relay Circuit Open Or Shorted.

  • Dodge
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
4
AreaAuxiliary emission controls
91
FaultThe specific fault in that area

What it means

On Dodge vehicles, P1491 means the powertrain control module has detected a fault in the radiator fan control relay circuit. The module commands the relay on or off and monitors the circuit. It saw an open circuit or a short that did not match the commanded state, so it set the code. Which relay and fan arrangement is involved depends on the model and engine.

Symptoms

  • Engine overheating, especially in traffic or at idle
  • Radiator fan not running, or running constantly
  • Air conditioning performing poorly when stationary
  • Temperature gauge climbing higher than normal
  • Check engine light on
  • Fan running after the engine is switched off

Possible causes

  • Faulty radiator fan control relay (stuck or failed internally)likely
  • Damaged, chafed or corroded wiring in the relay control circuitlikely
  • Poor connection or corroded terminals at the relay socket or connectorlikely
  • Blown fuse or fusible link feeding the relay or fanpossible
  • Faulty radiator fan motor drawing excess current or shortingpossible
  • Fault in the powertrain control module driver for the relayrare

How to diagnose

  1. Read all stored codes and freeze frame data to see engine temperature and conditions when the code set, and note any other codes.
  2. Check engine coolant level and condition, as overheating can accompany this fault.
  3. Visually inspect the relay, its socket, the connectors and the wiring to the fan for heat damage, chafing, corrosion or water ingress.
  4. Check the relevant fuses and fusible links for the fan circuit using the wiring diagram for the specific model and engine.
  5. Using a scan tool with bidirectional controls, command the fan relay on and off and listen for the relay click and fan operation.
  6. Test the relay itself on the bench or by swapping with a known good identical relay, following the wiring diagram.
  7. Check for power, earth and control signal at the relay socket, and test the control wire for continuity and shorts to earth or voltage.
  8. Check fan motor current draw and condition, and only then suspect the control module if the circuit tests good.

How to fix

  • Replace the faulty radiator fan control relay.
  • Repair or replace damaged wiring and clean or renew corroded terminals and connectors.
  • Replace blown fuses or fusible links after finding and fixing the cause of the overload.
  • Replace the radiator fan motor if it is seized or drawing excessive current.
  • Repair or replace the powertrain control module only after all wiring and components have been proven good.

Can I keep driving?

Medium severity

Short, careful trips are possible, but without a working fan the engine can overheat in traffic, so fix it soon. Stop immediately if the temperature gauge climbs towards hot.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

This code for other makes

Nearby codes