Toyota bZ4X Owner's Manual: If the 12-Volt Battery is Discharged

If your vehicle's 12-volt battery is discharged, the EV system may fail to start. You can follow the steps below to restart the system or contact your Toyota dealer or a qualified repair shop for assistance.

Restarting the EV System

If you have access to jumper cables (or booster cables) and a second vehicle with a functioning 12-volt battery, you can jump-start your vehicle by following these steps:

1. Ensure both vehicles are parked securely on a flat surface. Engage the parking brake and turn off all electrical accessories.
2. Locate the battery terminals on both vehicles. Identify the positive (+) and negative (-) terminals.
3. Connect one end of the red jumper cable to the positive (+) terminal of the discharged battery.
4. Attach the other end of the red jumper cable to the positive (+) terminal of the functioning battery.
5. Connect one end of the black jumper cable to the negative (-) terminal of the functioning battery.
6. Attach the other end of the black jumper cable to an unpainted metal surface on the engine block of the disabled vehicle-avoid connecting directly to the discharged battery.
7. Start the engine of the assisting vehicle and let it run for a few minutes.
8. Attempt to start the EV system of the disabled vehicle by pressing the power switch.
9. Once the EV system starts, carefully disconnect the jumper cables in reverse order.

Precautions and Important Considerations

• Never allow the clamps of the jumper cables to touch each other while connected to a battery.
• Avoid connecting the negative jumper cable directly to the discharged battery to prevent sparks.
• If the EV system does not start after multiple attempts, seek professional assistance.
• After a successful restart, drive the vehicle to recharge the 12-volt battery and have it inspected by a Toyota dealer.

Proper battery maintenance is essential for avoiding unexpected breakdowns. If the 12-volt battery frequently discharges, it may indicate underlying issues such as aging battery cells or electrical system malfunctions. For owners of the Toyota bZ4X, following these jump-starting guidelines ensures safe and effective recovery, preventing further complications in critical EV components.

When connecting the jumper (or booster) cables, depending on the situation, the alarm may activate and the doors locked.

2. Open the hood
3. Open the positive (+) battery terminal cover.

While pressing on the claw, open the cover as shown in the illustration.

4. Connect a positive jumper cable clamp to on your vehicle and connect the clamp on the other end of the positive cable to on the second vehicle. Then, connect a negative cable clamp to on the second vehicle and connect the clamp at the other end of the negative cable to .

Use jumper cables that can reach the specified terminals and connecting point.

1. Positive (+) battery terminal (your vehicle)
2. Positive (+) battery terminal (second vehicle)
3. Negative (-) battery terminal (second vehicle)
4. Metallic point shown in the illustration

5. Start the engine of the second vehicle. Increase the engine speed slightly and maintain at that level for approximately 5 minutes to recharge the 12-volt battery of your vehicle.
6. Open and close any of the doors of your vehicle with the power switch OFF.
7. Maintain the engine speed of the second vehicle and start the EV system of your vehicle by turning the power switch to ON.
8. Make sure the "READY" indicator comes on. If the indicator light does not come on, contact your Toyota dealer.
9. Once the EV system has started, remove the jumper cables in the exact reverse order from which they were connected.
10. Close the positive (+) battery terminal cover.

Once the EV system starts, have the vehicle inspected at your Toyota dealer as soon as possible.