my Toyota Highlander Third Generation (2014-2019) battery keeps dying, what could be wrong

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked in a safe location with the engine off.
• Disconnect the negative terminal of the battery for safety.

Tools Required:

• OBD-II scanner
• Multimeter
• Basic socket set
• Wire brush or terminal cleaner

2. Inspect and Clean Battery Terminals

• Remove the positive and negative battery cables.
• Use a wire brush or terminal cleaner to remove any corrosion from the battery posts and cable connectors.
• Reattach the cables, ensuring they are tight and secure.

3. Test the Battery

• Reconnect the battery and use a multimeter to measure the voltage. A healthy battery should read around 12.6 volts or higher when fully charged.
• If the voltage is low, replace the battery with a new one.

4. Check Alternator Functionality

• Start the engine and measure the voltage at the battery terminals with the multimeter. It should read between 13.7 to 14.7 volts.
• If the voltage is lower than this range, the alternator may need to be replaced.

5. Resolve Parasitic Draw

• With the vehicle off, disconnect the negative battery terminal again.
• Connect a multimeter in series between the negative battery cable and the battery terminal to measure the current draw.
• If the draw exceeds 50 mA, begin pulling fuses one at a time to identify the circuit causing the drain.
• Repair or replace the component responsible for the excessive draw.