wjnelson72

So my 2004 is300 wont start. All it does when I turn the key is click once. It did this to me once before and all I did was replace the battery and it worked again. This time though, no luck. So, I replaced battery, the starter, the relay, checked all related fuses, the neutral saftey switch, and still all it does is one click. My key will lock and unlock doors, Im stumped. Any thoughts?

2001SolarY

Ignition switch. Not the key cylinder part. The electrical contact unit.

wjnelson72

Okay, i'll check it out, thanks

Arsenii

Hello,

Does the ignition turn on and stay on when the starter clicks?
Do you hear the Fuel Pump running when you turn the key to Start Position?
Are there any strange noises coming from the starter area when the key is turned?

Make sure there are no signs of the starter being jammed in place, check that neither the starter nor the B+ wire are not heating up when the key is turned to the Start position, and that it is completely silent while you keep the key turned. If that's good, check the voltage between battery terminals, and them between Starter B+ terminal and the Chassis Ground while turning the key, both measurements have to have the same values, difference in more than 2V would indicate that either the Ground or the B+ terminal is damaged.

To check if the Ignition Switch is at fault, if the ignition turns on, go under the hood and short the Starter relay with a thick gauge wire and see if the engine will crank, though don't keep the jumper there for long, just in case. If even the Ignition doesn't come on, you will have to take the plastics around the key off until you can reach the pigtail for the switch. With that, this switch only operates with signals, there is no loads on it, so it is unlikely that it went out.

Hope this helps and best of luck!