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  • Bolec WL701 Low Coolant Level Alarm Kit with Probe

Bolec WL701 Low Coolant Level Alarm Kit with Probe


Specsheet: Download PDF
Instruction Manual: Download PDF

Bolec WL701 Low Coolant Level Alarm Kit with Probe

The WL701 is a 12 and 24 volt low-coolant level alarm kit designed to protect your engine from catastrophic failure for automotive and remote water pumping applications.   The WL701 provides a visual and/or audible alarm if the coolant falls below the chosen level.

The WL701 will give a warning of a sudden loss of coolant (ie burst radiator hose), alerting you to switch off your engine to prevent damage due to overheating.   In the scenario of a burst radiator hose, there may be no visible steam and your temperature gauge will read normal because the sensor is not immersed in coolant.   The WL701 is more effective than a temperature gauge in this situation.

The WL701 features an anti-slosh delay, so the alarm will not sound every time you drive around a corner.   The WL701 also features external outputs if more powerful or more convenient indication is required.   For example, the WL701 can be wired to shut down the engine low-coolant is detected.

Kit includes:

  • WL701 low coolant level module with built-in buzzer and output relay
  • 1/8NPT water level probe with connector and brass boss
  • 8-pin wiring harness
  • LED for external visual indication


  • A built-in alarm sounds once the coolant level drops below the sensor in the radiator.
  • The unit is protected against reverse polarity.
  • An AC signal on the probe prevents scale or other deposits from building up on the probe.
  • The signal that goes to the coolant level probe is AC or alternating current. This prevents electrolysis and scaling and material build-up on the probe.
  • A slosh filter detects and averages out fluctuations in coolant water level due to movements in the vehicle. This 7-second slosh delay prevents false alarms when driving on windy roads.
  • The WL701 has a self-test mode. That is the beep to let you know that it is working.
  • The WL701 has a built-in buzzer/alarm that will sound if the coolant level falls below the coolant level probe. The WL701 also has relay outputs, so you can connect to an external light or the ignition to shut down the engine (in a Genset or irrigation pump setup)
  • A fail-safe circuit detects & will sound the alarm in case of a broken lead on the sensor connection.
  • A user-selectable self-check function checks and sounds the alarm for a short time each time you start your engine. Default off jumper J2.
  • A user-selectable alarm condition is continuous or pulsing. Default continuous jumper J3.


  • Cost effective protection against engine damage caused by coolant loss
  • The WL701 alarm is not limited to radiators in a vehicle. This device can be used to monitor the level of drinking water in an RV or four-wheel-drive. It can be used for irrigation applications, to turn on or off a pump when the reservoir reaches a certain level.
  • You can use it in plastic, but need two probes to complete circuit.

Wiring Diagram


Dimensions:  Approximately 78x102x29mm overall.

Voltage:    12/24 Volt DC Negative Ground systems.

Probe:    Sensing via AC signal only. No plating occurs.

Contact Rating:  12/24VDC 1.5amp, Resistive.

Time Delay  Approx. 7 seconds after water falls below probe.

Bolec Electronics

Founded in 1978, Bolec Electronics has developed a portfolio of over 80 products and a reputation that survive and thrive in some of Australia's harshest environments. Bolec Electronics is the OE supplier to some of the world's largest truck and engine manufactures.

Premium quality

Easy to install


Designed and made in Australia