Ultrasonic liquid sensor, controller and buzzer to detect low coolant… | SwedeSpeed

I have a 2011 with 57,000 miles and decided to replace the pressurized overflow tank and add an ultrasonic liquid sensor to the outside of the tank. Warning-These steps may be a bit involved….

The sensor turns “on” in the presence of a liquid (antifreeze) and turns off if no liquid is detected. A controller was added with logic which looks for the sensor to go “off” -no liquid and then turns on a buzzer.

See attached photos: The controller receives the status of the sensor green wire input 5 on the circuit board (0=off/no antifreeze or 1=on/antifreeze present). The controller logic then turns on a buzzer (Output 6 on the circuit board) if no liquid is detected (input 5 off) on controller board). All parts were ordered from DFROBOT except for the buzzer which was ordered from Amazon (see later).

The power to the sensor (red +12V and black GND) is shown on the POWER side of the circuit board). The +12v power is taken from the green with orange stripe from the passenger headlight via a terminal pin/wiring that comes with the DFROBOT kit. I slid this pin into the back of the connector(wire side to make contact without cutting into the OEM wiring). This was the closest 12 volt source that powers up when the car starts.

Although the current draw for the entire set is probably less than 0.1 amps, l be adding an inline fuse later. The controller ground is mounted to the passenger side ground terminal with the existing engine ground.

The output from the controller (pin 6) DIGITAL side of circuit board goes to the buzzer +12V. The sensor ground is attached the GND on the DIGITAL side of the circuit board.

The programming logic for the controller is open source program code. I found a similar program for this sensor/controller at DFrobot web site examples.

I first tested this buzzer sound by leaving it in the engine compartment. I will credit Volvo….I could barely here it from the drivers seat with the engine running. I decided to mount inside the car at the door jam-to-dash board area. I can definitely hear it now!

More photos coming later…

The parts (sensor, controller, case, extra wiring, etc) were from DFrobot (about $58)
Gravity: Digital Buzzer For Arduino
$1.90SKU: DFR0032x 1$1.90

Gravity: Non-contact Digital Liquid Level Sensor for Arduino
$11.90SKU: SEN0204x 1$11.90

ABS Transparent Case for Arduino UNO R3
$3.90SKU: FIT0603x 1$3.90

DFRduino UNO R3 with IO Expansion Shield and USB Cable A-B
$25.70SKU: DFR0216-2x 1$25.70

Gravity: 3 Pin PH2.0 to DuPont Male Connector Digital Cable Pack (30cm)
$6.00SKU: FIT0896x 1$6.00
5 ItemsSub-Total$49.40
Registered Mail (US) (Weight: 0.28kg)$8.00
Total $57.40

buzzer was a little weak sounding, so I picked up a louder one (85-90 db) from Amazon. (about $7)