I have searched like crazy and can not find the specific issue resolution for my problem.

My car around 10% of the time does not start, or even turn over for that matter. When I say 10% it is a guesstimate, some days it will work perfectly all day and the next day it will do this 25% of the time. Also, it seems to do it less on the first turn but if I turn it off and retry to start I can usually get it to do it nearly half the time(on the bad days). Doesn't matter if I turn it off and immediately turn the key again or if I wait a few seconds. It has tried to fire for like half a rotation and then had to be turned off and restarted but that has only happened a few times. I turn the ignition off and re-turn the key and it will start right up. Sometimes I have to turn it off and try to start 3 or 4 times before it will fire. The key does not have to be removed. The key always turns when inserted.

It did die one time, not sure it's related but thought I'd mention it. It died about 100 yds after starting, turned it off and back on and it started as usual.

I got another key and the problem does not seem to be getting better, in fact I think it's getting worse. Due to my new key seeming worse I am going to try using my old key for a while and see if notice any difference. I did order the other key because my key would not unlock except with IR unless I smacked the key on a hard object, then it would work great for a while. Figuring it had a bad antenna. Was hoping there was a connection to the starting issue but not such luck.

I have checked fuses referenced in other threads and they are all good, plus it is an intermittent issue so had a hard time thinking it is a fuse. Also, battery is at 12v. Gonna check fuses again and get a more compressive check of voltage tomorrow night. This is my first Mercedes and I am really hoping to get thee problems ironed out soon.

I am currently thinking it is either a bad EIS or Starter solenoid. If anyone has any ideas they will be greatly appreciated. If I find an answer I will post it.

I have an email to an independent Mercedes shop(great reviews) to see what they think of the issue and to give me an estimate for a new EIS(want prices on worst case scenario).



Updates:
I've taken it to an independent Merc shop and they ran STAR diagnostic which came back with no codes including specifically no codes on the EIS. They put in a new starter relay and asked me to take the car for the weekend and report back. Didn't have a problem from that Friday afternoon until Saturday at around 8pm when stopping by the store on the way home from a busy day. It happened once more Monday morning when leaving for the day to work.

I am currently waiting to hear from the shop as I have communicated this all to them and looking for their suggestion for the next step. Not worrying about them calling right away as I'd like to see if starts getting worse again.

 

The fact that it died after running a bit may point to a bad CPS. If you're going to shotgun the diagnostics that's the cheapest/easiest start.

 

In my reading I thought I read it would turn over if that went bad? Problem is most of what I've read is diagnosing specific problems and I didn't want to ask questions on a bunch of old threads.

That was however on my radar, not as much lately tho. I am awaiting a price now on a full scan.

 

You're correct, just the stopping would be CPS related.

 

Makes sense...

I am scheduled to have diagnostics run Friday so we will see what they say.

 

So they said no codes at all and they are putting in a new starter relay and want to see if I have any problems over the weekend. Not confident it is going to fix it but lets hope... My experience with relays is they rarely go bad but when they do generally they're either bad or not, not intermittent. I am hopeful it is not but still think it's an eis issue. The only other thing I need to find out is if they checked the starter connections.

 

Just got the car back and upon returning to work I turned the car off and on 20 times with out any problems. Seems odd to me that the relay would cause my problems but I am hopeful that it works!

 

Does the work order say relay or selenoid? Lots of amps goes through the starter selenoid and it's not uncommon for them to get pitted and fail intermittently with failures increasing over time until total failure.

 

Relay, it was $15 so I know it wasn't the solenoid. I asked them if they checked the starter connections and they said they visually inspected it and it doesn't appear to have corrosion or to have bad connections so they didn't do anything with it. They are trying to diagnose a little at a time which I can appreciate as my bill is under $100 at this point. I will say I am very happy with their service so far. I am relatively good with working on cars just with a new job haven't had anytime to diagnose the issue any further and I have discussed with them detailed parts of the work they were doing and everything seems legit. He said they did the relay because they don't want to run my bill up but would rather replace a small part first to eliminate the problem. Ironically they are working on it the way I would in replacing cheap stuff first before spending a bunch of time and money on the big ticket items.

In my time working with relays I've never seen an intermittent connection issue, the only thing I can think is the contacts are worn and it is not getting a good connection. I told my wife the likely hood of it being the relay is similar to the chances of getting struck by lightning twice this weekend(no technical data has been gathered on that ridiculous statistic analogy) but it is still possible.


EDIT: Just want to say how happy I am with the shop, I forgot to say they checked that the cam sensor magnets had been replaced and found a few seals that were not repaired correctly. Seemed as tho they went through all the common issues via bulletins on the vehicle. I know they are fishing for more work but regardless it's nice to have it all checked out at no cost to give me the option.

 

+1

 

I was beginning to think it was fixed... Saturday it did it to me in the middle of the day while leaving a store and this morning sure enough it happened when I went out to my car to leave. Emailing the shop now

 

Please let us know what happens. I am having the exact same problem as in your video.

yesterday morning, for the first time ever, it paused about 5 seconds before the starter decided to turn over and start the engine. Interestingly the high idle wasn't very high even though the engine was dead cold. I don't know if the two symptoms are linked.

Anyway I pulled the car out of the driveway and got halfway down the street before I starting thinking this was going to be the last time the car starts ... so I turned around and went home. Parked and tried to start -- nothing, just like in your video. I'm glad I went back home to get another car

This morning I pulled the three fuses in question -- all look good. Next up for me will be the starter relay.

Another interesting symptom, is that since a few weeks ago my rear view mirror and left side mirrow have been dimming during the day. Very annoying, especially when you park in a covered parking structure, you can barely see out those mirrors. I don't know if this is related at all.

 

John, I kinda think it is your starter. So if it has a "dead spot" then it was receiving power but turning very slowly for 5 seconds before it reached a position where it could spin.
In that case it's "easy" to test by applying 12v to the starter directly.

 

Does it make a loud "click" when it fails? If so then the starter solenoid is getting juice and working but the starter is failing. No click then it's something before the start circuit and you've already replaced the relay.

 

When I had the 5 second delay there was no real turnover ... just a few seconds pause. It did not feel like a mechanical problem to me.

I pulled the relay after my last post and looked at the pins ... everything is pretty clean in there. But I will pick up a new one today and pop it in to see if it makes a difference.

I hope it's not the starter ... doesn't look like it's easy to get to :|

Thanks. John

 

Big difference is mine will work completely normal if I turn it off and retry. Sometimes it take a few tries but nonetheless it is intermittent. I have heard of random things happening like wipers being strange when it involves the EIS but not sure the mirror would be that type of weird symptom.


This. Starter check is pretty easy... Mine makes absolutely no noise when trying to start. I am going to try to remember when starting to always hold in start position as I have the habit of turning to start position until it starts to turn over then I let go and let the car start itself. and I want to make sure it's not just some weird delay as that is a little different symptom.

I would much rather it be a starter problem as it is DIYable if you want it to be vs EIS where you have options but they are limited to which dealer to take it to for the repair. I was quoted $550 for starter and labor which is a little high in my opinion but it's still better than replacing the EIS.

I don't think our problems are the same but a relay is cheap so you might as well do that first. I am waiting to hear from the shop to see what they'd like to do next. If I knew this was something that would happen on occasion but it would always start on the second try I'd just leave it be but I know my luck and when I'm out of town all next week for work I know if it's going to altogether stop thats when it will be!

I will keep everyone updated as one of my greatest pet peeves is when people post in forums and just stop with the updates. So they look for help and never let anyone know what it ended up being. I am new to this forum but will help where I can!

 

Okay, I'm pretty sure it's my starter now.

I bought a replacement relay from the local dealership for $15 ... didn't make a difference. So this time I tried turning the key while listening carefully inside the engine compartment ... prominent click, one or two other clicking like noises, then the smell of burning solenoid/armature

So, needless to say I will be purchasing a starter today with hopes of receiving it by this weekend so I can install it.

I'm looking at a Bosch reman unit for ~$200 plus ~$100 core charge. Is there anything different I should be looking at?

Thanks. John

 

I think your diagnosis is right on. If those are the same symptoms that the Indie had I'm surprised they put in a relay. If the relay was bad they wouldn't have gotten the 'click'. Probably brushes in the motor and dirty armature so if you want to save $ and have the time DIY. Hope it goes well.

 

On mine they gave me a loaner and they're going to drive mine for a few days with lights hooked up to the starter and see if they can confirm the problem :/

 

"They" didn't put in the relay ... I did. It was only $15 from the dealership so I figured not a big deal if it wasn't the issue. (btw if anyone wants to buy a new MB starter relay cheap, let me know

Starter motor is on order from RockAuto ... Bosch reman for $180 plus core. I'm looking forward to another round of arm-scratching and knuckle banging under the car when it arrives

 

You might be able to use our tech articles here as a reference for any future problems you may have. They might help you when you track down issues that puzzle you.

-Luccia

 

Shop has lights hooked up to everything and believe the ecu is not sending ground to the starter relay. They are keeping it over the weekend and I'm out of town for work next week so I told them no rush.

 

Say what? The starter is always grounded. If there is a click coming from the starter solenoid then it's getting juice that far and the only thing to stop the starter from spinning is either the solenoid to starter connection is bad or something in the motor like armature or brushes. IMHO, I don't claim to be an expert.

 

My bad! Starter relay not getting ground! Got my kids distracting me and missed a word there...

Also, no clicking whatsoever when it doesn't work.

 

I'm guessing it's your EIS without having knowledge of what/if the ECU has any input.