How To Troubleshoot A Car Battery Isolator

Your battery has been giving you problems lately and you need to know how to troubleshoot a car battery isolator? A car has two batteries: the accessory battery and the main battery. A battery isolator job is ensures that both of the vehicle batteries are charging as they should. When a car battery isolator is not working properly it will cause problems with the car batteries staying charged. There are several different ways to troubleshoot to find out what is wrong with your battery. You can follow a few steps to troubleshot a car battery isolator to find out why your car battery is not charging.

To Troubleshoot a car battery isolator you need:

  • electrical tape
  • digital mulit-meter


  1. Find out is something has caused your battery to not charge. Check to see if your headlights or any other electrical device has been left on for an extended period of time. Maybe your car has been exposed to extreme weather and has been sitting for a long period of time. Look to see if any sparks or wires are have gotten loose.
  2. Look for corrosion around the battery terminals. There could be dirt or any other type of build up around the battery. This can cause for your battery to loose and not be able to hold a charge. Clean the corrosion off from around the battery terminal then check to see if the battery will hold a charge once the battery area clean.
  3. Disconnect the large gauge cables. A car battery isolator has two large contacts and two small contacts. Make sure that you disconnect the large cables. These cables affect the battery's positive terminal, so when disconnecting make sure that they do not touch the metal on the engine compartment. You can use electrical tape to cover the cables ends to prevent this.
  4. Test your car battery isolator to see if it will engage.  Place you meter on the large contacts. Switch on your car's ignition to trigger to see if it engages. Set the meter to ohms and if you get a 0 ohms then this indicates that the isolator is working. If you get an open load reading then this indicates that your cars battery isolator is not working. If this is the case you may have some serious electrical issues that need to be checked out.
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