A battery isolator is an intricate part of your car's electrical system, as it works to split electrical current between several batteries in order for the car to have a backup electrical source. Testing to see if a battery isolator is working properly is a simple process if you have a digital multimeter. This allows you to see if there are problems that need to be addressed further with the vehicle.
Place the black cable of your digital multimeter on one of the large contacts on the isolator and the red cable on the other large contact.
Set the digital multimeter to "ohms" by turning the dial to the correct setting.
Switch on your car's ignition to engage the digital multimeter. A reading of zero ohms means the isolator is working. A reading above zero means that there is an electrical issue that needs to be checked.
