you need to do a millivolt check across all battery power AND ground connections to find your problem.
Start with the power feeders first, all the way to the starter, and all the corresponding grounds.

Good luck!

The W220 is strangely heavy on its battery, though judging by the number of ECU's in the trunk of the W221, I'd expect newer cars to be even worse. My battery is about 100AH / 800CCA, but only uses a fraction of that for starting. ANY 12V car battery can start a W220 (it only takes a fraction of one Amp-Hour) but its electrical faults or long-term parasitic discharge that kills the battery.

Just opening the door or trunk adds several amps load, and its double-digits with the ignition on, so that drops the battery voltage before you even get your multi-meter probes in there. 12.25V isn't bad, and certainly wont' cause starting problems. Mine starts with as little as 11.5V.

Yes, you should aim to keep batteries above 12.4V all the time, then it will last. You have to shut all the doors and lock the car, then wait tens of minutes before everything goes to sleep before the battery load drops to its' long-term value of typically 50mA, and only then will you see the real, resting. Of course, you can't get to the battery then, so you really need to run test leads or remove it altogether to get the real voltage. So I would worry too much about ad-hoc measurements.

Nick

Thanks Nick. That was very helpful for me in the long run.

I removed my EIS in the morning and sent it out to have it checked out and get a replacement.

If the replacement EIS doesn't solve the issue, I will have to dig in and do what kraut suggested. I've never dealt with an issue like this before. I'm just hoping it's the EIS and that's the end of this issue so I can move on to take care of other issues and get started with my exhaust. Thanks once again to all. I've definitely learned alot going through this and I don't regret it too much.

If this issue is resolved with the EIS, I will post all the unique symptoms I faced for me to determine it was the EIS so that it can help others.

I so wanted to record a video of the EIS removal but wasn't able to do so properly as I needed a second hand. When I put it back, I'll try to record the procedure.

EIS replaced
 

It's been two days since the replacement EIS was installed. Also bought a second set of key. Both seemed to have been working so far. Started the car about 5 times so far. It's still too early to tell if the issue has been resolved. All I can say is the guys who I sent the unit to, did a proper job replicating the EIS on the replacement unit.

So if anyone needs to have their EIS replaced for their W220 for whatever reason, you can order a replacement for $500 from their website. The owners name is Alex.

The website is http://paylesscarkeys.com/

I can vouch for their work. They had same day turnaround. The same day they received my unit, they sent out the replacement as well.

Looks like the problem is back. Am sitting in the car trying to get it started. So changing the EIS and a new key didn't solve the issue.

One thing I still notice which is something tusabes mentioned is that I keep on hearing all sorts of buzzing and humming sound in the car.

Next thing I'm thinking of is getting an oem battery. Can anyone send me a link where I can get an oem battery? I assume the dealership would be the place correct?

Only Mercedes dealer sell oem battery

It does sound like you have a weak battery. Or all your electronics are not shutting down and are
Draining your battery

Is it group 94r and AGM ?
Or just a generic battery ?

As long as you have a new AGM battery size 94r
It should work fine in any brand

Pep boys has the Bosch AGM battery size 94r

Online Amazon has the AC delco
https://www.amazon.com/ACDelco-94RAG...art/B006N91C2M

To eliminate a battery drain issue you can get the battery brain t3 from Amazon
It's a remote control battery disconnect so it completely disconnects the battery from any drain when you leave your car . Click they keyfob and it reconnects the battery when you return to the car. I would install this at the same time you put in the new battery , since it installs on top of the battery . This will eliminate a lot of potential issues

Thanks for the info again.

In the morning the car started fine. Actually the car had started everyday for the past 5 days. Took it to work. And then when heading home it doesn't wanna crank. I tested the battery at the time when it was not cranking. It read 12.23, which was lower than the last time when it did start.

Had my wife drive the other car to the parking lot and tried to hook up jumper cables and add some juice to the s600 battery. Still it didn't crank.

I am a bit perplexed now. I am glad I didn't spend that 1000 on a new EIS from dealership. I am not sure what else to try except the battery.

I'll buy a battery from dealership or the link you sent. and I might as well buy that battery drain protector. I don't know what else to try.

Ok so it seems like my battery is an AGM? On the description of the Superstart battery on OReilys site it states:

Sealed AGM construction for leakproof and spillproof protection

http://www.oreillyauto.com/site/c/de...0423&ppt=C0005

This isn't a battery issue IMO.

12.23V while "low", is plenty to at least try and spin over the engine in the real world - My battery had most likely a damaged cell and would consistently start on below 12V without an issue, and even when it started to run noticeably lower it'd at the very least try to crank.

The intermittent nature also does not tally up with a battery fault - Batteries don't generally suddenly stabilize enough charge without any intervention enough to spin over a V12. Its possible but unlikely to happen as often as you've been able to randomly start it subsequently. Also charging/Jumping the battery has had no effect or made make/any difference.

Providing the connections are good, clean and tight, and its not something as simple as a loose/partially broken connection to the battery (possibly caused when the new battery was fitted), I'd be inclined to forget it and move on and check what's going on at the starter motor during a non crank situation.

The connection to the battery should be good. The issue started before the Battery replacement. I had trouble getting to the starter because I didn't have an impact set to undue the primary cats. The bolts were pretty rusty. When I took it to the shop and describe them the issue they kept saying it shouldn't be the starter.

I actually bought a starter and didn't install it due to their advice. If I get the car started by tomorrow morning, I'll get the starter installed so that way at least the starter was actually looked at.

Anyways, let's see how it goes.

BTW, something I do notice when the car does start. There is a slight delay maybe half a second after I turn the key the engine turns over and start. This maybe normal since it's all electrical. Usually on regular key systems, when the actual key turns, the engine turns over as well.
On my 12 Fusion I don't even feel half second delay when I turn the key. The engine turns over right away.

Might be a bad ground or bad starter cable

Spent one hour last night sitting in car with the key in ignition and finally it started. Taking it to a shop to check the whole starter system in a few hours. Let's see if this issue will come to an end.

The starter was replaced. There were few vacuum lines that were found disconnected and reconnected when the shop removed the starter. Let's see how this goes.

So far the battery, starter, starter relay, and EIS were replaced along with a new key. If the problem is still there, then I would have to look into wiring which would be a whole new ballgame.

Won't crank & radiator fan goes full speed
 

Hi, tks i purchased a MB coder reader & it won't link up to car. I checked all fuses & fusible links under passenger footwell.

Won't crank & radiator fan goes full speed
 

Hi, tks i purchased a MB coder reader & it won't link up to car. I checked all fuses & fusable links under passenger footwell.

Update:
Looks like replacing the starter solved the issue. Glad it wasn't the fuses or wiring harness. The car has started every time for the last few weeks and I've been driving it everyday.

In summary, my original issue was that car would start imtermittently.
Though many things can cause cars to start intermittently, this cars problem was the starter.

The unique symptom that I saw with this was that if it didn't crank, then turning the key once to start and leaving the key in there and waiting sometime for 10-30 minutes would start the car up automatically.

Only saying this in case someone runs into a similar issue, then they can suspect the starter if they can start the car leaving the key in ignition for some time. My starter never clicked and had around 94k miles when failed.
Hope this helps someone out in the future.

Removing the starter on these are a real PITA(Pain In The you-know-where). They are almost impossible to see. You have to remove the catalytic converter. And hope that the bolts holding the front cats aren't rusted or molted into the piping.

2000 s500 won't crank
 

Mine won't crank when it's cold. New battery new starter. Key turns to position 3 but I noticed the time shows when it won't start. When it starts it shows P etc. The car won't come out of park in any key position.

I think my issue is the shifter. I am told it has to be coded to match eis.

For those who are concerned if is your starter you can short 30 and 87 by removing relay under hood. I used a paper clip while someone else held key in. Car turns over but won't start.

may try replacing fuse under passenger foot well. But don't think a fuse can fail.

Car has 225,000 miles.

a firm here in NC called Beckham says they can test the shifter for proper operation but can't recode a used one.

eBay sells the three parts ECU, eis and shifter. Is it worth giving that a shot. Stealership will take $1500 and the car isn't worth it.

Dean

not cranking when cold is a. Very common issue and its usually the eis not the shifter . The soldered connections in the eis have cracked open with age and shrink in the cold weather making poor contact

the problem of not shifting out of park when you do get it running is either the shifter or brake switch

i would get the matched set of parts on eBay but remember you need 4 matched parts not 3 - shifter eis ecu and the key!!

To clarify, once the car starts the shifter is fine. I have also heard that heating the eis boards at low temp could reset the eis solder joints?

yes some people have been able to repair the soldered joints on the eis . If you want to try repair of the eis as a first step it's the logical first step , there are companies that will repair your eis so no programming will be needed