Chrysler Repair: chrysler starter problems, solenoid switch, starter solenoid

Question
WHEN I WAS DRIVING HOME FROM LUNCH I HEARD A LOUD NOISE LIKE METAL SCRAPING. IT LASTED 2 MILES. I PULLED OUVER TO MAKE SURE THERE WASN'T ANYTHING UNDER MY CAR. IT STOPPED SUDDENLY. WHEN I LEFT TO BACK TO WORK, I CAME OUT AND HEARD MY CAR TRYING TO START AND SMOKE COMING OUT FROM UNDER THE HOOD. I DISCONNEDTED THE BATTERY TO MAKE IT STOP. WHAT DO YOU THINK IT COULD BE?

Answer
One more possibility is that the ignition switch's function for "start" is stuck closed. The way you could diagnose that is to find the relay, unplug it, then disconnect the brown wire at the starter solenoid, then reconnect the battery and plug the relay back together and listen as you do so to see if it clicks softly. If it does, then it more than likely means the villain is the ignition switch. If there is no click, then the ignition switch is probably not the problem (though there is another possible explanation here: that the relay is stuck closed so then it wouldn't click; but that would mean that BOTH the ignition switch AND the relay were bad at the same time, which is very unlikely). So anyhow, this is just to be thorough and give you all the possibilities. These can be better verified with a neon glow light or voltmeter by the way; if you have one I can give you more instructions.
Roland




Hi Penny,
'Good response to that seemingly possessed starter motor!
What it sounds like is that the starter solenoid, which is a switch located on the starter motor, has stuck in the 'on' position OR alternatively the starter relay is stuck in the 'on' position. It may seem strange that the starter motor could run by itself, but actually the battery power goes directly to the motor however it is only applied to the motor by the solenoid switch. The other thing the solenoid does is to apply a temporary gear connection between the starter motor gear and the ring gear on the engine so that the engine is rotated until the point where it starts, and then that temporary gear withdraws to a resting position (It is called the Bendix gear). The scraping sound that you heard was probably the Bendix gear still connected or partially connected to the engine ring gear.
The self-start experience was due to either the solenoid switch closing itself to the 'on' position or the starter relay falsely telling the solenoid to close. The starter relay is supposed to only energize the solenoid when you put the ignition key in the "start" position, but it too could fail and stick in the closed position even though you released the key from the start position.
I suspecct that there is some damage to the starter motor, from being run to the point where it began to smoke, and/or to the solenoid and Bendix gear and/or to the ring gear on the engine (I hope that last one is not the case because that would require separating the transmission from the engine to replace it). The starter relay, an inexpensive device usually mounted on the inner fender shield on the driver's side of the engine compartment, might be the villain in this whole history so it should be checked to make sure that it isn't flakey and self-closing it's internal switch.
Now that things have cooled off, you might try starting the engine to see if the motor will crank the engine or not. Of course you need to put the clamp back on the battery (but leave it loose enough to pull it off quickly), and if it still wants to start itself then I would of course disconnect it. If you can get to the starter motor (still with the battery disconnected) find a brown color wire that is attached to the solenoid, and disconnect it. Alternatively you could find the starter relay (tell me the year and model and engine of your car and I may be able to help you identify it) and disconnect it. If either disconnecting the relay or the brown wire stops the self-start, then the relay is bad; if not, then the solenoid is bad. You might be able to replace the solenoid without removing the starter motor; that depends upon how much space there is to get at it. The relay is very easy to replace if it is the cause.
If the whole starter system is "dead" when you try it, then I suspect the motor has been overheated and will need to be traded-in for a rebuild.
If the motor starts the engine, and the cranking stops at the time you release the key,(i.e. everything appears normal) don't be satisfied that everything is o.k. It is likelly that it will fail again very shortly.
If you intend to try and fix it yourself at home, that is fine, but always remember to disconnect the battery before touching the big red wire at the start motor because it is "hot" all the time unless the battery is disconnected.
If you aren't inclined to do it yourself, then it might be wiser to have the car towed to a repair shop rather than run the risk of it starting up by itself again while you are driving and repeating this incident all over again.
Good luck and let me know if you have additional questions.
Also I'd be interested to know how it resolves itself.
Roland