Reptar0nIce

So I have a new issue. I was able to replace my starter, and now my car runs again! YAY! But I now now what caused the old starter to burn out. For some reason when I turn the key To ignition it starts to activate the starter motor and crank the engine. I can hear the starter running when the engine is running.

The starter activates once the key is in the ignition position, BEFORE I turn it to “start”. So if I left it there it’s just continue to turn the engine over without firing (since it’s technically not in start “mode”). What could be causing this issue?

ETA: I have keyless go, and starting it that way will also cause the starter to run with the engine on.

ETA2: I’ve also tried swapping around the starter relay with the fan/horn relay, but it’s still having the same issue.

E42AMG???

Pull the starter relay while it’s running, if it keeps going you know it’s I wire shorted after the relay and vice versa

Reptar0nIce

Thanks for the suggestion, that’s a great idea. I’ll give it a shot and report back.

I didn’t think it was an issue with the ignition cylinder since the keyless go button does the same thing.

Reptar0nIce

The verdict: starter continues to run when I pull the relay. So there’s definitely a short somewhere down the line from the relay. Does anyone have a wiring diagram of the ignition system? My car has a built in radar detector, and I’m wondering if where they tied it into the ignition system is causing the short.

TheAlphaDirtbag

Check to see if you pinched the wires from the starter to the battery

Reptar0nIce

I went under my car and can’t find any pinched wires running from the battery to the starter. The positive starter wire is definitely getting a constant 12 volts. And the starter solenoid ground isn’t showing constant 12 volts (which I guess is obvious since it’s not running all the time the battery is hooked up. I can’t for the life of me understand why it’s running all the time, even when I use Keyless Go... It’s acting like it’s a bad ignition switch, but that shouldn’t cause the same problem if I use Keyless Go right?

I’ve removed both the starter relay and fuse and it will still activate the starter when I turn the key to ignition on.

Reptar0nIce

I found the wires that go from the SAM to the alternator and starter and can’t find any breaks at all. So I don’t see how the starter could be grounding out... The positive wire from the battery is fine too.

tlambert

Where did you buy the starter?

Maybe the problem is inside the starter.

Reptar0nIce

I bought it from the auto parts store, but I doubt it’s the issue. This was occurring before I replaced the starter, and is what caused the old one to burn out. I doubt it could be the new one. The solenoid is getting power too soon, and that power isn’t stopping when the key is in the on position.

Could a faulty SAM cause this? Pulling both the fuse and relay still causes the starter to crank when I set the key to the on position (before “start”). Disconnecting the wire that runs to the starter solenoid (the purple one) makes the starter not run with the key in the ignition on position. So I guess that means the fault can’t be after that point...

Also I guess there’s a chance it’s the EIS? Maybe the fault in there is “on” all the time which is why the starter still runs when I use keyless go.

rapidoxidation

Can you put a proper diagnostic tool on the car? There's a solenoid in there somewhere that keeps the starter spinning even after the key is released - until the engine is running and the solenoid is told to let go. If the solenoid doesn't get that "stop" signal, that's a problem. If the solenoid is stuck (welded contacts) that's a problem too.
A wiring diagram will help you follow the heavy power line back from the starter.

Reptar0nIce

Found out what the issue was. Looks like there was some sort of short in the front SAM that was causing the starter to stay on. I got a replacement SAM, swapped it in and the problem is fixed! Wanted to post here in case anyone runs into a similar issue, the SAM might be the culprit.

bas2018@

Hi am having the same issue
Which Sam did you Replace
I understand that it’s the front but do you mean the Sam with fuses thanks