my Toyota Highlander XU70 (2020-Present) battery dies overnight what could be causing this

Solution

1. Preparation

• Tools Required: Safety gloves, safety glasses, OBD-II scanner, multimeter, ammeter, basic hand tools (socket set, wrenches).
• Safety Warning: Disconnect the battery before performing any electrical work to prevent shorts or shocks.

2. Battery Replacement (if necessary)

1. Disconnect the Battery
   • Use a wrench to loosen the negative terminal first, followed by the positive terminal.
   • Remove the battery hold-down clamp.
2. Remove the Old Battery
   • Carefully lift the battery out of the tray, ensuring not to tilt it excessively.
3. Install the New Battery
   • Place the new battery in the tray and secure it with the hold-down clamp.
   • Connect the positive terminal first, followed by the negative terminal, ensuring tight connections.
   • Apply battery terminal grease to prevent corrosion.

3. Addressing Parasitic Draw

1. Identify the Circuit Causing Draw
   • With the ammeter connected, check each fuse in the fuse box one by one by removing them and noting the current drop until the draw falls below 50 milliamps.
2. Repair or Replace Faulty Components
   • If a specific circuit is drawing excess current, inspect and repair or replace the affected components (e.g., lights, modules).

4. Alternator Check (if necessary)

1. Remove the Alternator Belt
   • Use a wrench to loosen the tensioner and remove the belt from the alternator.
2. Test the Alternator
   • Connect the multimeter to the alternator terminals and check for proper voltage output while the engine is running.
3. Replace Alternator (if faulty)
   • If the output is below specifications, remove the alternator and install a new one, ensuring to set the tension on the belt properly.