moodywv

Hi,
I have a 2006 ML350 that no longer starts. I drove it home one evening with everything appearing to be normal, parked, and the next day, inserted key, and everything is normal until it comes to cranking engine, then nothing happens. Below is how the car is behaving:

· Locks still controlled remotely by key (all normal)
· After key is inserted, key is recognized and allowed to turn
· Radio, seats, everything appears to be working normally
· Turn key to start position, not even the smallest effort to crank but I do hear fuel pump starting up, radio comes on, all lights on dash light up normally for when key is in run position but engine not started

I have attached a computer to the OBD port that has ability to read the ML350 systems (not just OBD functions) and see a fault in communication with the ECU with all OBD functions failing. Also checked battery, good.
After some digging around, I have seen multiple suggestions including bad key (I did try a key from another Mercedes and it did not allow me to turn the key), bad EIS, faulty computer, grounding, battery (checked as good), etc.

Does anyone know what the likely culprit is or how to determine the issue? Taking to Mercedes dealer is not an option I would like to pursue as this seems like it could get very expensive.

UPDATE 09/24/19
Removed EIS and opened up and found no problems. Put in freezer for an hour, hooked it back up and did not change how care behaved. While doing this testing, I did try to shift gears and transmission moved from Park to Neutral. Does this mean that system accepted key? Starting to think that ECU or wiring could be issue.since connecting scanner to OBD port shows ECU communications failure.

Thanks

texterted

Read this thread... HERE

moodywv

Ted,
Thanks very much for the pointer. Read that thread earlier and my next step is to pull the EIS based on the instructions.

I didn't know if the lack of ECU communication or that everything seems completely normal (dashboard lights, etc.) up to the point when it should crank might point to something else.

Thanks

texterted

It may well do, I just thought that thread would be a good starting point for you (no pun)!

Funnily enough, mine's been playing up of late too. Turn the key and nothing happens on start. I squirted some switch cleaner into the key hole and it's been fine since. Hmm, I'm not convinced of a cure but I'll let it develop.

Good luck!

51mike

If it is turning over but no start, I would check for fuel pressure front of the engine of you have pressure then the crank shaft sensor one on driver side under manifold close to the transmission.

moodywv

Mike,
Thanks for suggestion. Unfortunately, it is not turning over at all. Once I turn the key to the crank position, nothing happens other than the gritting of my teeth

51mike

Ok did you check the starter? Also tip of the key have plastic for infrared Ray's make sure that is clean and also try to check the ignition if there is dirty or debris. Sometimes the reader might not read the specific ecu unless you read it last week and now no communication then its pointing ecu or connection plug or wire problem. I would also check fuse for that ecu . On my range rover out of the blue it would not crank at all which was driving perfectly fine like minutes ago. .... after long story short it was engine management fuse. The scanner was giving all kinds of codes it is worth a check I dont think benz have engine management fuse... but check....

Genjet

Just to recap, my 2011 ML 350 would start normally but occasionally turning the key did not engage the starter. As time went on, it happened more often and I couldn’t narrow down under what conditions that caused it.

Eventually along with no start, the “key on” stuff wouldn’t work but would all come on when the starter engaged. Again, totally random and the car would eventually start if tried multiple times, often starting on the first try.

MBZ dealer did the free airbag recall and I mentioned the start issue. Upon completion they noted it needed the EIS. Unsure if they diagnosed it or just made an educated guess. Estimated ~$1000 fix (plus tow if it was needed).

I researched on the internet and found the speed shop Pressertech in Georgia. Unlike eBay vendors, they are able to replace the part if it isn’t fixable. (Estimated $150 up to $595). A very helpful and patient Scott (owner) spent time on the phone with me as he just did one of these recently and was able to explain how to remove/replace the part.

Sent in the EIS with the key by FedEx. I was told it wasn’t fixable and I had the new MBZ part installed within 36 hours of removing it. Both keys work and it’s good as new! FedEx there, they tried to fix and returned old and new part w/key via priority USPS at my request. Tuesday night to Thursday afternoon.

With all the electronics and this part known to go bad, it made sense to replace it especially after the MBZ dealer confirmed it.

You have been researching I see as you mentioned freezing it. I saw that too somewhere along with opening it. I saw where checking components inside the EIS helped some people. Some power connections were not soldered correctly and a visit to a cell phone repair store fixed it for some people. I didn’t open mine and was told it was unfixable so possibly a micro issue.

Maybe some other places on eBay could have fixed it, but I chose a reputable speed shop that would definitely get me a new part of it was not fixable. I fixed it for $595 plus shipping there. Took the gamble as it could have been $150 if fixed so I still saved a few hundred bucks.

It actually took me longer to get the trim back into position than it did to replace the EIS itself. Also, I used a couple flat screw drivers and long nose players to remove the chrome ring. YouTube helped with some of that.

Hope me this helps!

DSherman

Read here, this might help.
http://www.mercedesmedic.com/mercede...epair-ezs-eis/

Maj. Dundee

With a test light or DVOM, check fuse #14 in the right side fuse box.

moodywv

Good article, Thanks. Unfortunately several of the tests can't be run right now. No spare key and no communication with ECU over OBDII port (even though key turns and dash lights up). Leaning toward EIS, ECU, or wiring in between them right now. Going to spend some time tracing wires/power this weekend. Do you know of any wiring diagrams related to ECU and wiring to OBD II port?


Thanks for the fuse suggestion. I will check the fuse tonight. Previously, I went through most of the fuses but don't remember specifically checking this one. What does it control?

moodywv

Update:
Checked Fuse 14 as rec'd. Fuse is good. I did pull the ECU out of the car and attempted to start car afterwards and saw no difference in behavior. Does this point to ECU/wiring to ECU? If so, does anyone have wiring pinout for ECU connectors. I would like to check voltage and grounds at connectors.

Thanks

Maj. Dundee

First of all, please UPDATE YOUR PROFILE in USER CP to include the year of you ML and wether it is Gas or Diesel.

Maj. Dundee

Is this the ECU that you removed and why did you remove it?

moodywv

HI,
Yes, that is the one. Just checking to see how difficult to remove and send for repair if determined to be a likely culprit. While disconnected, tried to start car and did not see any difference in behavior or ability to communicate over OBDII port.

Thanks

moodywv

Forgot to mention, also looking at tracing wiring on CAN bus connections and checking voltages at connectors

Thanks,

Maj. Dundee

Moody, you have to invest in a scanner. Thanks for updating.

moodywv

Hi,
I currently have the which reads/sets Mercedes specific systems. Is this comparable to what you are suggesting?

This is the reader used above. It shows communication with some systems (e.g. Airbag) but not with ECU.

Thanks

Maj. Dundee

Clarify, but not with ECU.

moodywv

Hi,
WIth the key in the running position (but not running), the scanner shows "Fault in communications with the ECU" when attempting to connect to Transmission, ECU,and Electronic Stability Program. The only system it successfully connects to is the AIrbag which appears normal under all tests/live data stream viewing. I assume this rules out the OBDII connector being bad and the scanner being bad. FYI: Same behavior when key is not in running position. Standard OBDII scanning fails also.

Also, I can change gears (Park to Neutral and back) with the key in the running position. Does this mean the TCU is functioning at some level? Also, since the key is accepted and turns and gears can be changed, does this rule out EIS? I have tested with another key from a different vehicle and it does not turn.

Does the ECU only get powered on once the key is turned to the running position? I would like to check voltages at the ECU connector but currently don't have a pinout for the two connectors.

Thanks. Appreciate the help.

Maj. Dundee

What are the code numbers for the no communications?

moodywv

No code numbers. When trying to connect to anything but Airbag system, a window pops up and says:

Fault in communication with vehicle ECU. Please confirm:
1. This vehicle is equipped with the system.
2. The diagnstic connector is OK.

Also, this scanner has been used on this vehicle before and all of the functions worked as expected.

While I have checked every fuse and relay I can find (back fuse box, engine fuse box, left side fuse box), I am going to recheck and start checking voltages on various circuits while key is on and/or in crank position as soon as I can get a helper to turn key while I check voltages. Any tips on where to start checking voltages?

Thanks

Maj. Dundee

Moody, you men to tell me that when you get that message on your Launch screen you do not have any codes in any module, especially in the CAN module?

moodywv

Hi,
Unfortunately, I don't get anything other than communications failure message described above. Will look into investing in another scanner.

I have been looking into voltages in engine compartment fuse box and have found that the starter relay has no power to either side of coil and no power to either side of contacts. Assuming that one side should have 12 Volts and the other is grounded by ECU to activate starter to activate coil.

Also, I have seen Circuit 15 mentioned several times and have checked the associated relay. When key is in on position, it is not energized meaning power is not supplied to this circuit (power is present on one side of contacts but contacts are not closed).

Thanks

Maj. Dundee

Moody, I will look at the diagrams and get back to you in a few hrs. Hold tight.