Why is the Low Water Light Flashing on a Surface Mount Pump Controller?

• If a pump is running and the water source is depleted, the red Low Water light will begin to flash. This indicates that it is using the 30-minute restart delay.
• Once the delay ends, the Low Water light will stop flashing, and the controller will restart the pump.
• If water begins to flow through the flow switch the light will stay off and the pump will continue to run.
• If water does not flow through the flow switch the controller will stop the pump from running and the Low Water light will begin to flash again.
• This feature helps to prevent damage to the motor, damage to the impellers, and other dry-run wear and tear.

Inside the pump controller:

• Ensure the sensor wires are firmly connected to the WC and WH terminals.
• Either wire can go in either terminal (no positive or negative polarity).
  • Check for:
    • Loose wires
    • Rust, corrosion, or water damage
    • Pests such as ants, spider, etc.
    • Animal damage to cables

Clean and secure any questionable connections or replace damaged cables.

If you're using a water level sensor, make sure the factory installed red bridging wire between the WC and WH terminals has been removed.

• This red bridging wire is used for dry testing or non-sensor setups.
• Leaving it connected overrides the sensor and will interfere with proper function the low water sensor or flow switch.

Remove this wire to ensure the controller only responds to the sensor or switch signals.

If the Flow Switch is not installed horizontally, it can cause false stop signals.

• Ensure the sensor is:
  • Installed horizontally.
  • There is water is the connected pipes.
  • Connected to the WC and WH terminals.

A surface pump can lose prime for several reasons. Turn off the solar isolator and perform the checks listed below:

• The water source has been depleted.
• There is a leak in the suction pipe.
• A foot valve was not installed on the suction pipe.
• The foot valve is faulty or is not closing properly.
• Air has been sucked into the suction pipe.
• The suction pipe has not been installed properly.
• There is a leak in the pump.

Once all these are checked, reprime the pump and turn the solar isolator on.

If the water sensor is now properly submerged, you can either:

Option A: Let the controller automatically restart the pump after the 30-minute delay.
Option B: Manually clear the timer and restart the pump:

• Turn OFF the solar isolator.
• Wait 30 seconds.
• Turn the solar isolator ON again.

This will clear the restart delay, and the controller will attempt to restart the pump. If there is another reason for the controller to stop the pump (e.g. the tank full light is on), the controller will not restart the pump.

• If you suspect the sensor might be faulty, place a loop wire between the WC and WH terminals.
  • If the Low Water light starts flashing or turns off:
    • The low water sensor is not in water
    • Water is not being pushed through the flow switch
    • Or the switch/sensor is faulty and needs replacing

Important: Remove the jumper after testing — don’t leave it permanently installed.

Sensor Failure: If the sensor is underwater, the wiring is correct and not damaged, the loop wire test worked but the light stays on when the low water sensor or flow switch is installed, the sensor is faulty and need replacing.

If the water level sensor is underwater, the wiring is correct and not damaged, the loop wire test worked but the light stays on when the low water sensor or flow switch is installed, the sensor is faulty and need replacing.

Conclusion:
A flashing Low Water light means your controller is in a 30-minute restart delay to protect the pump and allow the water source more time to replenish itself.

This is normal and safe.

If the Low Water light is still flashing, the sensor or controller are likely faulty. Contact Commodore Australia’s Technical Support team for further assistance.