05 e320cdi-- random no crank/no starts- no codes
 

This recently started

Turn key- get normal lites/GP lites/ etc. Go to crank-- NOTHING - as if battery is dead...

Battery is 12.5 v

Happens several times over 15 minutes--

then randomly starts
also-- weird- same as above-- zero crank-- then as i am returning keyfob to OFF-- halfway on return-- it cranks and starts

also- has happened - were all of the above-- cranks/starts on return-- then when i return key to OFF position-- car stays running???

ANY IDEAS????

When you say no codes....did you scan with a scanner that reads all MB codes?

I've had some issues with the first part of your description - the no-start situation.

Next time you start the car keep an eye on the glowplug light immediately after you switch the ignition into position #2.

The glow plug cycle on the CDI's is very, very short but you should always see the light come on for at least quarter second before going out.

If you don't see the glow plug light and the car won't crank/start I've done some diagnosis that might be helpful.

I haven't experienced any of the other symptoms you've described so my info may not be relevant.

Tim- I actually experienced the No Glow plug lite/No crank last winter... Fixed with ECU rebuild and re-program.

This time-- the Glow plug lites do come on every time,,, then no Crank or as explained --random cranks/starts

My Indy does NOT have Star-- but is a legit Mech w/ Some pretty good expensive toys

You need to check the electrical part of the ignition switch as it should not stay running with key in the off position and also should not try to crank when you are in process of turning it off.
Not sure how it’s all held together on the ignition barrel but it sounds like it’s got loose and is moving around.
You are not going to have any codes because technically nothing is wrong as such.. if it is a loose electrical portion of switch then it’s moving as you turn the key so it does not reach the crank stage as the whole unit may have turned rather than the insides clicking round.

Got it. Where did you get the ECU? They appear to be totally unavailable even from Mercedes?

I have the Starfinder and wiring diagrams at my shop - do you have access to them? Haven't researched it but I think the starter motor signal comes through the front SAM and utilizes a cube relay to provide the actual starter solenoid signal. I believe the ECU initiates the signal but I'm not sure.

Could be as simple as a flaky relay. Or it could be much more complicated.

Let me know if you want me to dive into the schematic for the starter circuit.

TIm

This car is about 8-10 years too new to have a ignition switch that is actually a switch or has any tumblers in the key mechanism.

Thanks- I will let u know

More info now--

apparently the indy- has found when it goes into NO CRANK-- the tach is bouncing from 500-900 rpm NO CRANK/NO Motor running...

when it DOES start (Randomly) the Tach is at Zero- like it should be when in Glow plug lite position... in other words when he initiates GP Position and sees NO TACH move - he knows it will be a successful crank/start

when he turns to GP Position and sees Tach Movement-- he knows- it will be an NO/CRANK/NO START

hope that helps some guru's out there

Well that's not good - that symptom wouldn't present if it was just a stuck starter relay.

The tach signal would almost certainly be coming from the CDI control unit and it appears to be confused.

Are there any codes in the N3/9 CDI ecu?

As a pure guess could a bad crank position sensor be feeding a spurious signal into the process that's making the ECU think the engine is actually running when it's not? That would explain the no-start when the tach is moving around prior to starting.

I generally don't agree with the crowd around here that proclaims The-240D0-OM61X-is-the-best-thing-ever-made crowd but in this situation they are absolutely right. Even with a SDS it's very difficult to diagnose this kind of intermittent problem and once you get into the mysteries of the black box ECU there are really no possibiliites of fixiing anything once you verify the inputs are correct.

As mentioned before it sounds like a wonky ignition switch to me.......or like was possibly a bad crank position sensor, but that would most likely throw a code.... If possible, try another ignition switch??

It is only a guess. It never happens to my CDI, touching wood.

I suspect it is something electrical loading the battery if the tach is bouncing around. May be a bad starter or weak battery. Try something simple first. Turn on the headlights and see whether it dims badly when starting. Try a new battery. Good luck.

Ignition switch module not certain if a foxwell can test it but I would think so.

Indy checked Both the Crank position sensor and camshaft sensors- both appeared ok...

I heard about a diesel GL that would start/run for awhile then stop running. It was very sporadic. Guy sold it to new owner for $2k. He found a flooded rear SAM module. Replaced SAM and never looked back on hit new $2k ride:).

Did he replace Rear SAM w/ Used one? Does Rear SAM -usually require dealer Coding?

Murphy's law... Should have kept the e300td- knew this CDI - would cost me more w/ all the Computers/SAMs etc. ... oh well- If I only had a good INDY in Illinois- who likes/respected these OLD MB diesels

Rear SAM controls the tank mounted fuel pump. Non functioning rear SAM would disable the car.

I'm not sure about newer E-class cars but in the 2005-2006 era SAM's do require version coding when installed however its not the full-blown online phone-home-to-the-father-land-for-authorization SCN coding that's required for emissions or theft relevant parts the newer models require. It can be done with a stand-alone Star system and it's quite easy. I've replaced front SAM's with junkyard replacements and the process was a menu-driven 10 or so questions/answers and then save to the replacement SAM.

The RPM signal in the CDI's is generated by the N3/9 CDI control unit and reported on the CAN where its picked up by the instrument cluster and reported to the driver. The thing that I keep focusing on is why is the CDI ECU apparently reporting an RPM reading when the engine isn't running? If you can get an RPM signal on the tach without starting the engine with the key in position 2 that's a good sign the ECU is highly confused about it's state of affairs.

This is where things get almost impossible from a diagnostics perspective. Is the ECU confused because 1) its getting bad/confliciting data from 1 of the 24 sensors that feed it information to make decisions 2) a problem with it's power source or 3) The ECU is failing and losing its mind.

And of course it's not an either/or situation - it could be some combination of 1,2 and 3 of the above.

You mentioned your independent Tech verified the crank and cam sensors are good. How did they do this? Did they put a scope on the relevant pins and look at the waveforms? Or did they just look for codes associated with those sensors?

If I were doing diagnostics on this car I think I'd try to scope the crank/cam sensors and see what kind of waveforms were on the inputs to the crank/cam sensors when the car was KOEO and exhibiting RPM bouncing round/no start symptom. You should't see anything on the input lines of either of these sensors with the engine off. Bad data or noise on these lines could confuse the ECU.

It would also be helpful to use the real dealer-level STAR tool to check for codes/data from the N3/9 control module. The after market scan tools are pretty good but they generally don't get to all the data or codes that the full-blown dealer tools can access.

I'm sure the OM61X guys are loving this thread!

Modern systems are making some of us buy the known most reliable brands of cars. Where the dealers back shops are also well supported. With skilled staff.

Cost per mile of ownership can be very excessive otherwise. Actual cost of cars now has driven me to better general maintenance levels. Than factory recomended. .

Far too many money pit brands out there today.

My Indy- has A very expensive Snap on Scanner--- I read- it has limitations versus STAR scanner,,, Wed, it will go to Shop that has STAR scanner-

But i get the feeling that this is gonna get expensive from a few- stupid wire/sensors, etc.

does a 2002-2004 Lexus LS430- have all these computers and related issues to follow too? Just would like some luxury w/o the Stupid high costs...

yes- Love looking at my 87 300sdl... like driving on Expressway... but she is a bit of a turd lugging around town.

I've used a couple of aftermarket general purpose scan tools and currently own an Autel MS906 as a backup and non MB specific applications.

As you would expect the non-MB specific tools kind of vary in quality and coverage. Sometimes they provide 95% of the coverage of the Star system and sometimes that don't have any coverage for some components. I have an friend with a high-end Snap-on scan tool that couldn't connect at all to a 2004 CLK I had in the shop but my Autel and Star system had no issues connecting?

Hopefully the trip to the indy with the Star tool will get you some more information.

My daily-driver 2006 CDI has been suffering from the know ECU issue where the ground signal for the relay that powers up the CDI ECU isn't being consistently provided. This will result in a no crank when the key is turned to the start position. A key tell that you've got this problem is that the Glow-plug light will not illuminate when the key is turned to positon 2.

I've wired a manual push-button switch that I can press to manually provide the ground signal when needed, once the initial ground signal has been provided the car runs normally until turned off. Been using the car with this mod for about a year and it works fine but it kind of annoys me.

The ECU from Mercedes is over $1200 and its not available at this time. I'm suspecting It'll never be availalbe again. You can't swap in a junkyard ECU (even if you can find one) becausre the ECU is married to the EIS and steering column unlock ECU's.

You mentioned earlier that you have replaced your ECU? Where did you get your replacement ECU and who installed it?

ECU- was rebuilt by SIA electronics --ECU rebuilders
warrantied

The Baldur's Control Systems stand alone ECU is $1000 :D.

It eliminates half the nonsense sensors that are on the OM648 leaving you with only what is needed to operate the engine. You then also have the benefit of seeing every sensor and engine parameter as well as make changes. It's not going to be plug and play so it's definitely not for everyone.

No doubt.... but I don't think It'd play well with the interfaces to the 722.6, ABS, ESP and SBC brake system!

I don't know how some of the dealer techs can reliably troubleshoot these systems, the complexities are significant and intermittent electrical gremlins require a whole new level of skill sets.

well- Update- took it to yet another MB "Expert electronics Indy"- he was able to get the car to start by Jumpering in an Added relay to the front SAM - and bypassing the normal start relay ( I am sure I am not communicating this exactly)... regardless the car drove like normal for several days... and then- started to have a few no cranks/no starts... I was 50 mi from home when these issues started again. was able to get home....

next day-- GP lite as normal-- BUT BOUNCING TACH started again in position 2--- when car was NOT cranking???

The Indy that bypassed w added relay-- found several wires had been previously spliced/poorly re-connected.... fixed these... when he added the relay.

He suggested that the ECU was the issue- called the ECU rebuilder- no return calls.

AM I the ONLY Unhappy CDI owner???

I had many weird electrical problems on my 2009 E320. Spent over $2,000 on fixes. Finally solved the problem. The person that installed a new battery did not tighten the clamp on the positive battery post. The result was fluctuating voltage and sometimes no voltage for a short time. There had been sparking between the post and the clamp. Simply tightening the clamp solved all the problems.

You are speaking of one of the clamps on the posts on he Main battery in trunk???

What issues were you having? NO Cranks? Bouncing Tach??

thx

Yes, positive post on the battery in the trunk. Blower on AC was on/off frequently. Sun shade on the roof would not close. Finally no voltage anywhere. Tested by connecting volt meter to the 12v outlet in the ash tray so that i could monitor voltage while driving. DC voltage appeared normal. Set the voltmeter on AC. Normal is about 0.02Volts while driving. If the AC voltage reaches 0.05V AC or higher strange things happen throughout the system,

Tried starting car after 5 days -no attempts... after GP lite goes off- tach bounced for about 2 seconds w/ chiming -- then tach went to zero...

cranked- for several seconds -no start... repeated- tach stopped bouncing--car fired up... let it idle for 30 minutes-- took around block a few times... parked
, idled 10 more minutes... shut off... restart--no issues... shut off

came back 10 minutes later... Bouncing tach/ w chime... NO CRANK NO START... attempted few times- finally one time Tach --NO BOUNCE cranked for several seconds--NO Start....

Now back- to several attempts--BUT ALL w Bouncy tach... so NO CRANK

wtf!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Sure sounds like an intermettiant connection either canbus or ground. I can't find my diagram of where the canbus connectors are all located. They all would need to be disconnected cleaned and repeated. And I'd be doing the same with all grounds too.

I still think there may be a faulty connection somewhere. Remember there are many connections under the floor carpet on the passenger side where the floor slopes upward .