Faulty low speed fan relay (failed coil or stuck contacts); Damaged, corroded or loose wiring or connectors in the relay control circuit, including open circuit or short to earth or voltage; Blown fuse or poor power supply to the relay; Corroded or burnt relay socket or fuse box terminals; Fault in the engine control module output driver; Failed fan motor or its wiring drawing excess current and affecting the circuit (depends on model and fan layout).

P1490

Low Speed Fan CTRL Relay Circuit Open Or Shorted.

Pontiac
Powertrain
Manufacturer code
Medium severity

How this code is built

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

What it means

P1490 on a Pontiac means the engine control module has detected a fault in the circuit that switches the low speed cooling fan relay. The module commands the relay on or off and monitors the circuit. If the voltage it sees does not match the command, because the circuit is open or shorted, it sets the code.

Symptoms

Engine temperature rises or the temperature warning appears in traffic or when idling
Cooling fan does not run at low speed, or runs constantly
Air conditioning performs poorly or cuts out when stationary
Malfunction indicator lamp on
Fan running after the engine is switched off, or flat battery if the relay sticks on

Possible causes

Faulty low speed fan relay (failed coil or stuck contacts)likely
Damaged, corroded or loose wiring or connectors in the relay control circuit, including open circuit or short to earth or voltagelikely
Blown fuse or poor power supply to the relaypossible
Corroded or burnt relay socket or fuse box terminalspossible
Fault in the engine control module output driverrare
Failed fan motor or its wiring drawing excess current and affecting the circuit (depends on model and fan layout)rare

How to diagnose

Read the stored codes and freeze frame data, noting engine temperature and speed when the code set, and check for other cooling or fan codes
Check coolant level and look at the fan and relay area for damage, water ingress or burnt connectors
Check the relevant fuses and confirm the relay is the correct type and seated properly
Command the low speed fan on with a scan tool if supported, and listen for the relay clicking and the fan running
Swap the relay with a known good identical one, or test the relay coil and contacts on the bench
Check the relay socket for power, earth and the control signal from the control module using the wiring diagram for your model
Test the control wire for continuity, and for shorts to earth or voltage, with the module connector disconnected
Check the fan motor current draw and its wiring if the relay and control circuit are sound

How to fix

Replace the faulty low speed fan relay
Repair or replace damaged wiring and connectors in the relay control or supply circuit
Replace the blown fuse after finding and correcting the cause of the overload
Clean or replace corroded relay socket terminals or the affected fuse box section
Replace the fan motor if it is drawing excess current or is seized
Repair or replace the engine control module only after wiring and relay faults are ruled out

Can I keep driving?

Medium severity

Short, cautious drives are possible, but with the low speed fan not working the engine can overheat in traffic, so fix it soon. Watch the temperature gauge and stop at once if it climbs.

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