how to diagnose a Tesla Model S Original (2012-2020) that won't start

Tesla Model S Plaid/Refresh (2021-present)

Error Codes

1-2 hours

Time

medium

Difficulty

high

Severity

3 min read

509 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix a Tesla Model S (2012-2020) that won't start. Step-by-step guide with diagnostic procedures and repair instructions.

Affected Component

Electrical

Estimated Time

1-2 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect high voltage battery before performing any electrical repairs.
•Wear protective gloves and eyewear when handling batteries.

Symptoms

•No response when pressing the brake pedal and pressing the 'Start' button
•Dashboard lights and indicator lights are not illuminating
•'Vehicle Power is Low' message displayed
•Key fob not recognized or unable to unlock the vehicle
•Clicking sound when attempting to start the vehicle
•No sound or activity from the electric motors

Diagnostic Steps

1
Check the key fob battery level and replace if necessary.
2
Inspect the 12V battery voltage using a multimeter; it should be above 12.4 volts.
3
Connect the vehicle to a Tesla mobile service or Supercharger to check for system updates and battery health.
4
Use the Tesla Service Mode to check for any error codes or alerts in the vehicle’s systems.
5
Inspect the main battery connections for corrosion or loose wiring.
6
Verify that the vehicle's power management system is operational by checking the status of the Battery Management System (BMS).

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Multimeter
•Socket set
•Screwdriver set

Parts Required

•New 12V battery

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Symptoms

•No response when pressing the brake pedal and pressing the 'Start' button

•Dashboard lights and indicator lights are not illuminating

•'Vehicle Power is Low' message displayed

•Key fob not recognized or unable to unlock the vehicle

•Clicking sound when attempting to start the vehicle

•No sound or activity from the electric motors

Diagnostic Steps

1
Check the key fob battery level and replace if necessary.
2
Inspect the 12V battery voltage using a multimeter; it should be above 12.4 volts.
3
Connect the vehicle to a Tesla mobile service or Supercharger to check for system updates and battery health.
4
Use the Tesla Service Mode to check for any error codes or alerts in the vehicle’s systems.
5
Inspect the main battery connections for corrosion or loose wiring.
6
Verify that the vehicle's power management system is operational by checking the status of the Battery Management System (BMS).

Solution

1. Preparation

Ensure that you have the appropriate tools and protective gear.
Gather necessary replacement parts, including a new 12V battery if needed.
Disconnect the high voltage battery for safety.

2. Replace the 12V Battery

Access the Battery:
- Open the front trunk (frunk) and locate the 12V battery compartment.
- Remove any covers or panels as necessary.
Disconnect the Old Battery:
- Use a socket wrench to disconnect the negative (-) terminal first, followed by the positive (+) terminal.
- Remove any securing brackets and carefully lift out the old battery.
Install the New Battery:
- Place the new 12V battery in the compartment.
- Connect the positive (+) terminal first, followed by the negative (-) terminal.
- Secure the battery with brackets and replace any covers.

3. Reset the Vehicle Systems

Power Cycle the Vehicle:
- With the new battery installed, close the frunk.
- Press and hold the brake pedal, and then press the "Start" button to power on.
Check for Alerts:
- Look for any error messages on the touchscreen.
- If issues persist, perform a complete vehicle power reset by pressing and holding both scroll wheels on the steering wheel until the screen resets.