How to test a temperature sensor with a multimeter
Faulty gauges or temperature sensors tend to give unrealistic results when used, resulting in costly trips to mechanics and unnecessary maintenance, so troubleshooting is key. You need a full featured temperature sensor with first class accuracy.
A temperature gauge or gauge helps maintain a constant temperature for optimum engine performance.
To guide you through the steps of checking the condition of your thermometer, I have outlined four detailed ways to ensure that your thermometer is performing optimally.
In general, checking and troubleshooting temperature sensors includes:
1. Checking wires and common ground
2. Checking the Ohm signal from the Transmitting Device
3. Checking the ohm signal on the pressure gauge and finally
Checking the pressure gauge itself
In this guide, we will go over the above steps in more detail.
You will need the following tools:
- Digital multimeter
- Connecting wires
- Power Source (1)
- temperature sensor
- Calculator, pen and paper
- Sender unit
- By car
How to Troubleshoot a Failed or Outwardly Normal Temperature Sensor
Follow these steps to test your thermometer's performance:
- Checking wires and common ground. If the wires are not connected properly, or if they are frayed and disconnected, the temperature sensor will not work properly or even stop working. To check the common ground of a wire, hold one test lead to the ground wire and connect the other test lead to a wired electrical pole (ground) to make the multimeter work as an ammeter. It will display various values on the screen. The value must be zero for a grounded wire, otherwise a fault occurs.
- Checking the ohm signal coming from the transmitter. Many times you have found yourself in a situation where you need to replace the sender unit of the temperature gauge in your car. To test the ohm range, you need to connect the gauge to your multimeter, making sure you connect the positive terminals correctly (i.e. positive to positive and negative to negative). Make sure you are getting sensor readings in the empty and full positions so you can select the correct sensor assembly for your vehicle. After connecting the transmitter to the DMM in the ohm setting (you can choose 2000 ohms - you can scratch the terminals of the transmitter to get a more accurate reading), write down the resistance value or range. Knowing your sensor's resistance range will help you select a compatible sensor for your vehicle.
- How to check the ohm signal on a pressure gauge. To measure resistance, also known as gauge resistance, make sure no current is flowing into the sender box or any other component you would like to test, then insert the black and red plugs/plugs into COM and into omega VΩ respectively, switch the multimeter into the resistance mode labeled Ω and set the range to high. Connect the probes to the transmitter or device you want to test (ignore the polarity as the resistance is not directional), adjust the range on the gauge and get the OL value, which is often 1OL.
- Finally, inspect the sensor. You can do this by doing the following:
- Disconnect the temperature gauge from the sending unit.
- Switch the key (ignition) to the "on" position
- Connect the temperature sensor wire to the motor using jumpers.
- Make sure the temperature gauge reading is between cold and hot
- Switch the key to the position labeled "Off."
- Look for blown fuses in the car and those connected to the temperature sensor, and replace them if they are blown.
- Ground the wire (jumper) attached to the sensor terminal near the motor.
- Then turn on the ignition key without starting the car. At this point, if the temperature sensor shows "hot", it means that there is a broken wire in the transmitting device and you should repair the temperature sensor.
Summing up
I hope this tutorial has helped you so you don't have to go to the mechanics multiple times to check or repair the sensor. You can do it yourself and minimize the cost of your car. (2)
Take a look at some of our articles below.
- How to check battery discharge with a multimeter
- How to test a light switch with a multimeter
- How to test a three-wire crankshaft sensor with a multimeter
Recommendations
(1) Source Power - https://www.weforum.org/agenda/2016/08/6-sources-of-power-and-advice-on-how-to-use-it/
(2) minimize the cost of your car - https://tiphero.com/10-tips-to-reduce-car-costs
