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Bolec BEM502 – Engine Protection Panel


Meet the DEM502 Engine Shutdown Panel: Your Engine’s Ultimate Protector. Designed for trucks, buses, boats, agricultural machinery, and stationary engines, this compact electronic system features dedicated sensors for oil pressure, engine temperature, and more, ensuring real-time monitoring and instant fault detection. Powered seamlessly by your key switch, the DEM502 streamlines engine startup and guarantees smooth and secure operation. Rely on its precision and reliability to safeguard your engine’s performance.

Introducing the DEM502 Engine Shutdown Panel

Are you tired of the uncertainty that comes with engine operation? Whether you’re managing trucks, buses, boats, agricultural machinery, or stationary engines, the DEM502 is your solution for enhanced safety and performance. Designed for ease of installation and use, this compact monitoring system is your engine’s guardian angel.

Key Features:

  • Versatile Sensor Inputs: With a total of six sensor inputs, including four dedicated inputs and two spare inputs, the DEM502 ensures comprehensive monitoring of your engine’s vital signs.
  • Dedicated Monitoring: The four dedicated inputs can monitor critical parameters, including oil pressure, high engine temperature, alternator failure (belt breakage), and loss of coolant water.
  • Seamless Operation: Powered directly from the key switch, the DEM502 streamlines your engine’s startup sequence for smooth operation.
  • Built-in Time Delay: A built-in time delay allows your engine to start without sensor interference. The front panel LEDs indicate the timer’s progress, ensuring a hassle-free startup.
  • Fault Detection: The DEM502 provides an audible warning at the first sign of any sensor fault. It records the initial fault in its memory for quick diagnostics.
  • Alarm Silence: Take control with the key switch, which manages indicator LEDs and the audible alarm. When the power is turned off, the alarm silences, and the LED indicator goes out, storing the fault condition in the memory.

Recall and Diagnose Faults with Ease:

  • To recall the first fault: Press and hold the Recall Button while turning on the key switch. LEDs will flash, and the first fault will be indicated.
  • To recall subsequent faults: Simply press the Recall Button again.

Effortless Connections:

The DEM502’s terminal connections are straightforward:

  • Red: Positive 12/24VDC (key switch)
  • Black: Negative or Ground
  • Orange: Relay Common
  • Yellow: Relay Normally Open
  • Green: Spare 1 (DIP Switch 1)
  • Blue: Oil Pressure (DIP Switch 2)
  • Brown: Temperature Switch (DIP Switch 3)
  • White: Spare 2 (DIP Switch 4)
  • Pink: Alternator/Charge (To D+ Or +Ve to disable)
  • Grey: Water Level (To water level probe or Gnd to disable)

Customize for Your Engine:

A 4-way DIP Switch inside the unit allows you to adapt the DEM502 to your specific needs:

  • OFF: For Normally Closed sender switch to Ground (Closed when running).
  • ON: For Normally Open sender switch to Ground (Open when running).

Water Level Sensor for Water-Cooled Engines:

  • Disabled (Air-cooled): Top and middle pins connected.
  • Enabled (Water-cooled): Middle and bottom pins connected.

Tips for Optimal Performance:

  • Ensure good electrical connections between all points.
  • Keep sensor wiring away from electrical motors, solenoids, and ignition systems.
  • Maintain a single wire connection for the coolant level sensor, grounded if needed.

Upgrade your engine’s protection and performance with the DEM502 Electronic Monitoring System. Trust in its precision, reliability, and unwavering vigilance to keep your engine running smoothly.


  • Dimensions: 115 x 90 x 56mm (overall box dimensions)
  • Voltage: 12VDC negative ground (24VDC operation possible with internal modifications)
  • Current: 100mA at 24VDC, no load
  • Contacts: 12VDC 30Amp resistive

FeatureMurphy 09PWP12V09Bolec BEM502IRNBolec BEM502Bolec BEM302
IP ratingIP56IP56IP56IP56
Programmable timerYesYesNoNo
Auto shutdownYesYesYesYes
Fault memoryYesYesYesYes
Number of inputs6664
Number of outputs2222
Voltage range12-24V DC12-24V DC12-24V DC12-24V DC
Current rating10A10A10A10A
Dimensions (H x W x D)280 x 190 x 130 mm120 x 120 x 60 mm120 x 120 x 60 mm280 x 190 x 130 mm
PriceAround $2800$1,788$1,500$1028

For more information and to bring peace of mind to your engine operation, contact us today.

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