Vito Starter motor constantly running. Kicks in while driving

[ahuncutka]

Hi everyone,

I’m in a desperate need for some help.
In a nutshell: the new starter motor kicks back in and starts running while driving the van! I stop the van, turn the ignition off, take the key out and it’s still running. I have to disconnect the battery lead to stop the starter motor. After reconnecting the battery its fine, until I start the engine again, when few seconds later the starter motor comes on again… and again I have to stop the engine, disconnect the battery etc. etc.
Any ideas???

Now the longer story: Car: Mercedes Vito 120 3.0 CDI 2007 Automatic
2 months ago I have had a new starter motor fitted by my mechanic, as the old one didn’t disengage quick enough, but started every time all the time and never had any other issues.(with the old one)
After fitting the new Bosch starter, the van was still fine for 2 months… now 2 days ago I’ve got stranded 2 miles down the road. I have started the van as normal but as I was driving, the starter motor kicked in and was running simultaneously with the engine. I quickly pulled over turned the engine off. Nothing!!! Pulled the key out, Nothing!!! It kept running till it drained the battery!!! By then I could smell this burned electrical kind of a smell. Probably the starter motor…
So I ended up calling the recovery people. They have recovered me to the mechanics that fitted the starter the first place, they told me, that it can happen, probably a faulty item!  ???
So apparently it has been replaced under warrantee. I picked up the van yesterday I brought it home and it was fine. I’ve started it 10 times to see, and it seemed all was good.
Now after a cold night, this morning I went out, started the van, drove 50 yards, and here we go again!!! SAME Happened!!! While driving the starter motor kicked in. Only this time I could quickly come home… Than I’ve started it few time. Each time I had to pull the battery cable to stop it from running… the strange thing is that every time I start it up it behaves normal, I put the key in, start engine starter motor disengages as normal. Engine runs normal. All seems fine until I touch the accelerator pedal. Than the starter motor kicks in again. But sometimes if I just leave it to idle for 30s-minute it comes on without me touching anything. Just in Park and idling…
Any ideas anyone???
Please!!!

 

[Giantvanman]

First thoughts are that it something is either earthing or not switching properly…I'd get a multi meter on when it is doing it and check for frayed cable in the meantime…..take the steering wheel cowl off and check the ignition switch too. The starter solenoid could also be a culprit.

Might be a long shot but there is a bunch of cables inside a braided steel case that runs under and up between the engine and bulkhead which can fray and cause all sorts of issues.

In the meantime, once it has been started, try removing the starter fuse. I don't know if anything else is on the circuit but I think it is the only thing. By pulling the fuse, the starter shouldn't re-engage. This is just a guess and a stop gap. It really needs an auto electrician or someone good with a multi-meter to have a look.

 

[ahuncutka]

Hi Giantvanman,

Thanks for the info. well what I don't understand is, I thought of the starter solenoid or a relay if there is one. but the solenoid is part of the starter motor isn't it? and its absolutely brand new. But why would the solenoid make the starter motor re-engage, after the engine has been started, and has already disengaged once. to the extent that nothing can stop it... is there a starter relay maybe somewhere on these? or its straight from the ignition lock
Also could earthing really do this?

 

[Giantvanman]

Also could earthing really do this?

If the starter is getting power from another source due to frayed cabling.

The starter relay is cheap and easy. Otherwise, it's down to testing for an intermittent fault on the ignition switch or finding a frayed cable after the ignition switch.

 

[ahuncutka]

Hi,
Thanks for your help! It looks like my brilliant mechanic has found the issue! just like you have suggested. ( he has also read your reply on the forum) Some cables were shorting out in a black conduit that runs to the starter. Ordered another on approx. £70
Really appreciate it!