Help! Electric issue, problem starting the engine
 

Hello. I know I probably have to go to the Stealers for this one, yet I'd like to know if anyone has experienced this:
From time to time, the car will not start. The starter keeps turning for a few seconds, but the engine won't start. If it get out of the car, lock it with my remote, then unlock it, it will then start sometimes. If that doesn't work, disconnecting the battery helps everytime, it's like re-setting the computer. "Check Engine" light will then sometimes come on for a while, then go away on its own. The problem occurs every few days or so. The car is a W163 ML350. Anyone had this happen?

Clean or replace your CPS (crankshaft position sensor) behinde left cylinder head sensing flywheel. Very common solution for stalling issues and starting problem. I believe you have no problem with your alarm at all. You can do this by yourself for about $70. You need part No. A0031532728 Bosch No.0261210171. Bad CPS will make check engine light to come ON and cose engine to missfire. I would first just take it out and clean off all metal chips (from starter and flywheel) stuck to it because it is magnetic. Good luck!

Cool, thanks. Is this something I can do with practically no tools? I'll try that ASAP. I do have some sort of computer error issues as my windows will not now roll up automatically as I hit the window regulator switch, I now have to press and hold the switch for the windows to come up. They DO go down automatically now, just not always the other way around. Also, the remote will not always lock the car up, sometimes I have to play with the lock switch inside the car for the remote to start working again. All this could be from me disconnecting the battery quite a few times though.
Thanks again.

Yes, you're correct. That is because of battery disconnection. Check your owner's manual how to reset windows, radio and maybe resynchronize your remote key. I think you will need E10, 1/4" drive socket plus 10" or 12" extension to take off you crank sensor. Easy task. Mine was acting up till last month. I believe the sensor is still good, it was just dirty and metal shavings stuck to it was the problem but I already had new one so I replaced it. There are no mechanical parts (electromagnetic coil changing resistance) it should last forever.

Thanks a lot. Found these links on the net.
Hope my '05 ML 350 (W163) has the same sensor location as the older 320s do. Do they? What should I use for cleaning the sensor, rubbing alcohol? No one else writes of cleaning it, everybody is replacing the damn thing. By looking at it, where would it need cleaning, where it plugs into something? On the outside it's just a piece of plastic...

You will see right away when you pull it out. Blast of dry compressed air or just wiping it off with rag or paper towel will work fine. Metal button at the bottom of it. Remove/reinstall will take you 10 minutes. Put piece of scotch tape over the socket enge or magnetize it a little to keep the screw stick to it. You don't have to disconnect the wiring untill is out. Unplug it, plug new one in (if you are replacing it) insert it back into the hole, turn it to lineup mounting hole of sensor with threaded hole in the block and clamp it down with the screw.

OK, I haven't yet done any of this yet, but I did take the truck to a mechanic to do computer diagnostics. The computer shows no errors and no malfunctions, the truck is in perfect operational condition, except I know it really isn't. I guess when I started it last after disconnecting the battery, all errors got deleted from computers operating memory. The malfunction needs to occur again in order for the mechanic to be able to diagnose it? That's what we figured. I still keep the sensor thing in mind, just want ot make sure that it really is it. Any other suggestions? Thanks again.

My ML was not showing anything either only couple of times, when I floored it taking off it will show misfire on No.1 cylinder, leter No.1 and No.4, multiple cylinders. Starting problem was only ones in a long while. I replaced plugs and installed new coil with wires to No.1 cylinder and at fast acceleration, it would misfire again with check engine light and code P0301 or P0300. Then I checked the ML Star service manual for model 163 and found out that if it's not a spark plug, change your CPS Crankshaft Position Sensor.
I did and check engine light went off in about 10 miles of driving and never seen it to come on since. I cleaned the old sensor and I may try to install it back just to proof that it is still good. Manual explained nicelly that it has to misfire so many times per 2000 revolutions in order to give out any mulfunction code and when I drived normally, check engine and misfire code would never come. Good luck, Bernard

OK, since I don't want to get stuck on the street with this thing, I'll try to rev it up in Neutral at the shop. It should then also throw a code or stall... I'll try it on Monday. Thanks for the heads up.

No problem, I'm glad that my experience can be in help to someone. Today, I was actually thinking of reinstalling my old sensor back on to see, if it's OK but I didn't get to it.

OK, this issue is resolved, and it was, indeed, the CPS unit. Some of you may find this peculiar: the car is in Moscow, Russia. There are a bunch of official Mercedes-Benz dealers here. I went to one of them, just for kicks. The told me, diagnastics would run 3500 rubles, CPS (if that's what it is) would cost me 6500 rubles, and labor, which is just insane, would be 9500 rubles, all together this comes up to 19,500 rubles, which is about $570. Of course, they had a very nice selection of coffees and snacks in their customer waiting lounge though. I went to the local car parts market, knowing that this is probably the CPS, and sure enough, a Siemens unit was 1300 rubles, a Bosch was 2800 rubles, and OEM Mercedes part was 3900 rubles, so $38 - $114 range. Before I bought the damn thing, I wanted to make sure, that this indeed is the problem. Since I've disconnected the battery the last time I had to start the car, local mechanic's computer didn't show any errors. By the way, he only wanted 795 rubles for the diagnostics, just about $20. He kept the car for 3 days trying to get it to malfunction, but it started and idled just fine every time and every test-drive. He told me to pick-up the car because he can't do anything, the car is not showing any problems. I picked-up the car, drove it home (about a mile), parked it, and an hour later it wouldn't start again. Next morning it started with a "check engine" light on. I drove it to the mechanics again, it took him like 2 minutes to tell me it's the CPS (which we already knew), I got the Bosch part for $82 or so, and it took him 10 minutes to replace it, charging me another 795 rubles/23 U.S. dollars. I guess I could do the work myself, but I wanted to be absolutely sure that it was the CPS, plus the weather wasn't pleasant and I didn't feel like doing anything myself. The dealer sucks big time, always, and anywhere in the world. Sorry for the long story.

See, I've told you. You could of write in russian language and I would still respond. Had it for 8 years in school and still remember a lot. I believe there is a nice polish and russian forum on the net about Mercedes cars. Drive carefull in Moscow, hope you factory car alarm is working. Good luck and happy ML-ing! Bernard

I am having a similar problem with my 98 ML 320, intermittent starting. The only difference is the the car has not stalled after started........yet. Is it likely the same problem? That just haven't fully manifested yet? I tried to remove the CPS but after removing the bolt could not pull it out. Any thips for dislodging this stuck sensor. Thanks

My truck did not stall at first, either, in fact it has only stalled once, but it refused to start probably 4-5 times. I've only had the problem for about a week or so, I wasn't about to get stranded on the highway somewhere or in the middle of a 5-lane street during rush hour... Now, with this problem, the truck either starts right away, or it doesn't start at all, there is no middle ground, it's not like it struggles at first, doesn't catch, or kinda catches up and then dies... It either starts or not. Another hint: practically every time that the truck wouldn't have started, I was able to start it by disconnecting the battery for about 30 seconds - 1 minute, and then re-connecting it back. This resets the operating memory in the computer, erases the error code and what-have-you, it worked for me at first. That's how I've figured this must be an electronic/computer thing, not a mechanical failure such as spark plugs or something. The guy who changed it for me said that it's much easier to get access to it from bellow, he put the truck on a lift. Mine is a 3.7 liter, and getting to it from the top is a pain in the butt for sure. Hope this helps.

My 320 never stalled. Last winter starting problem was ones a week, but it would always start on second try. This winter only ones a month or one out of 100 starts. Misfire was there at all time but not often enough to throw off check engine light with code unless I was trying to accelerate very fast.
If the sensor is stuck, spray liquid wrench around it and use twist motion to loosen it up or open wrench at the base of connector and turn it a little, to pop it loose.

hi! i'm new at this...i have a 2003 sl500 took it out of storage today it was parked for six months battery maintainer didn't work,so the battery got fried,installed a new one.now the remote key don't work,the radio dosen't work,the tilt steering neither.it seems like the momorey is gne.can some one help.thanks...

Call any dealer for your radio security code, resynchronize your remote, reset windows and tilt all per your owner's manual.

thanks,good info.i'll do that.

it's me again.with the battery,now my radio nav.is fried maybe the man whoo boosted crossed + - would a 2004 radio would fit on a 2003 sl500 thanks....

I'm not sure, sorry. Try to post that question in the SL section of this forum.

I have a 1994 s 420 i unplugged and replugged some wires under the driver seat now the car will not start, the door can be locked and unlocked i think i need not sync my remote key with security system can you help?
Yhanks

Try to post this in S class section of this forum but resynchronization procedure could be found in your owner's manual.
Bernard