Possible reasons:
* Discharged battery: Check the battery voltage with a voltmeter.
* Poor battery terminal contact: Clean the battery terminals and check their tightness.
* Broken wiring: Check the electrical wiring for damage or breaks.
* Faulty alternator: Check the alternator for functionality by measuring the output voltage.
* Fuse or relay failure: Check the fuses and relays located in the fuse box for blown or damage.
* Faulty ignition switch: Try starting the engine using the spare key. If this does not help, the ignition switch may need to be replaced.
* Motor wiring problems: Check the motor wiring for damage or loose connections.
* Engine Control Module (ECM) is faulty: Check for ECM DTCs using a diagnostic scan tool.
Troubleshooting steps:
1. Check the battery: Connect a voltmeter to the battery terminals. The voltage must be at least 12.6 volts.
2. Check the battery terminals: Clean the battery terminals and tighten them with a wrench.
3. Check the fuses and relays: Remove the fuses and relays one by one and check them for burnout or damage.
4. Check the generator: Start the engine and measure the generator output voltage with a voltmeter. The voltage should be in the range of 13.5-14.5 volts.
5. Check Wiring: Visually inspect the wiring for damage or breaks. Pay special attention to wall transitions and terminal connections.
6. Check the ignition switch: Try starting the engine using the spare key. If this does not help, the ignition switch may need to be replaced.
7. Check motor wiring: Check all wires and connectors connected to the motor for damage or loose connections.
8. Check the ECM: If all other troubleshooting steps fail, you may need to check the ECM using a diagnostic scan tool.
If you cannot solve the problem yourself, seek professional help from an auto electrician.