Engine keeps running after ignition is switched off (Lexus ES300)

Last week I parked my 1998 Lexus ES300 in front of my house, and turned the key to the off position. The engine kept on running, albeit at a much lower speed than the normal idle speed, and started to make a horrible noise. I turned the key back to the on position, and the engine went back to normal idle speed and the noise went away. Turned the key back to off position, and the engine went back to the very low running speed, and the horrible noise came back. I did this a few times, pulling the key out of the switch as well, and the same thing kept happening. Since I didn’t want to leave the car running in that state, I thought may be disconnecting the battery terminals might result in the engine being turned off. I went into the house to get the tools, and when I came back out after about 90 seconds, the engine had stopped running. But I noticed that the battery had gone completely flat (no lights, remote wouldn’t work, etc.).

I called AAA the next day, and as soon as the guy connected his battery to my car, the engine would start and go right into normal idle speed (no low running state with horrible noise), without the key being in the ignition switch. This freaked out the AAA guy, who thought there might be a ghost inside the car! He connected his battery a few times, and every time the engine would start running at normal idle speed.

I think the problem may be with the switch being faulty, but I can’t explain why the battery went flat in about 90 seconds. I also can’t explain why the engine would go into the low running, horrible noise state at first when I was originally trying to turn the key off, but when the AAA guy connected his battery, without the key being in the switch, the engine would go into normal idle running speed, instead of going into the low running speed with the horrible noise.

Any thoughts would be appreciated.


It sounds like the starter solenoid has failed but in the connected position so it keeps the starter running at all times. When the battery went dead the starter then stopped, until power is connected and it runs again. The starter motor requires a lot of power from the battery and will drain it fairly quickly if it isn’t disconnected.

It sounds like your ignition switch might be bad, letting the circuits be active with the key off or out. It could also be a bad starter solenoid, or the starter circuit stays energized after the key is put back in the normal (run) and off positions-did you car sound like it was trying to start when the key was turned off?

did you car sound like it was trying to start when the key was turned off?

It didn’t actually sound like when you normally try to start. It was making a
terrible sound; I even thought may be the engine was seizing up! Still, it
is puzzling that when the AAA guy connected his battery, the engine went straight
into normal idle speed (no horrible noise), even though the key situation was
exactly like when I originally turned the engine off/removed the key, because
there was no key in the switch when he connected his battery.

btw, thanks a lot for the replies.

If the engine was really running while the battery was jumpered and it wasn’t just the starter motor turning the engine over then the ignition had to be ON also which would mean a bad ignition switch. It could be stuck in the START position.

I took the car in, and they replaced the starter (about $500, inc. tax).
All is fine now.

Thanks for your inputs.