If your car won’t start but the lights and radio are working fine, this could be one of several problems, possibly including a dead battery . The reason the radio, dashboard, headlights, and other electronics consume power while the motor is not related to the amount of current drawn by each device and what can interrupt the path.
Don’t rule out the possibility of a battery drain just because some electrical components are working. Batteries can sometimes work with electronic devices at a low charge. Headlights, radios, and other automotive electronics draw very little current—typically no more than 20-30 amps. On the other hand, motor starters draw up to 300A at the same time, which is too much power for a low battery.
If a battery test low level charge using a hydrometer, or if it fails the load test, it must be charged. If it accepts a charge or jump from another battery and the car starts, then the problem is solved. If it won’t start, it could be a blown fuse, a broken ignition switch, or a bad starter.
Check fuses, fuses and ignition switch.
If the battery is in good condition, check for a burnt out fuse or fuse . Check your vehicle’s owner’s manual for the location of the fuse box, then open it. If there is no power in the car, inspect the fuse for metal wire. If the metal wire inside the plastic housing is broken or damaged, the blown fuse prevents power from reaching the starter relay or solenoid.
You may need a fuse puller to remove the correct fuse and light source to see its internal components.
If the fuses are good, the vehicle’s ignition switch is faulty. The ignition switch is not a mechanical part that you insert your car key into; it is an electrical switch on which the mechanical part operates. In some situations, the ignition switch supplies power to the vehicle’s electrical components but not to the engine’s starter.
Diagnostics and troubleshooting an ignition switch is more difficult than checking for a blown fuse. A good rule of thumb, however, is that if the dash and dash do not light up when the ignition key is moved to the second position (between off and on), then there may be a problem with the ignition switch.
If you have Manual Transmission a bad clutch pedal position sensor can prevent the engine from turning over, allowing the electronics to work properly. The purpose of the clutch position sensor is to start the car only when the clutch pedal is depressed, so the car won’t go anywhere if it fails.