P1490moderate severityPowertrain
Low Speed Fan CTRL Relay Circuit
on 2003 Dodge Ram Van 5.9L V8 · 4WD
What this code means
The PCM has detected a malfunction in the low-speed cooling fan relay control circuit. The relay that runs the cooling fan at low speed for normal cooling is not functioning properly.
Symptoms
- Check Engine Light
- Engine running warmer than normal
- Cooling fan does not run at low speed
- Fan only runs at high speed or not at all
Common causes
- Faulty low-speed fan relay
- Fan resistor or module failure
- Wiring issue in relay circuit
- Corroded relay socket contacts
- PCM driver circuit malfunction
Diagnostic steps
- Test low-speed fan relay by swapping with identical relay
- Check relay socket for proper voltages
- Test fan resistor or speed control module
- Inspect wiring for opens or shorts
- Check PCM control output
Repair notes
Replace the low-speed fan relay or fan resistor module; repair wiring if damaged.
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