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2012 Genesis Sedan, Whatever Benz i have at the time
SOLVED: All electronics dead when engine running
Solved: New battery, key, fuses, and cleaning the SAM solved all of my issues.
ihave a 2002 Mercedes C240.
UPDATE: cooling fan stays on full blast anything past startup!!! i now have code P0600 its the only code i can clear it and read it but it comes right back. I'm going to assume that means the ECU is not fried and is communicating. how i wish i had a star.
Update: SRS LIGHT IS ON!!!!!!!!!
so I get In the car put the key in and it unlocks steering. Turn to position 1 steering wheel comes down and seat moves forwards. I have control of the center menus at this point and seat control. Turn to position 2 all dash lights come on all electronics work, and a weird constant loud tapping comes from the center behind the radio. Turn key to start car starts right up and drives like no issues. BUT the steering wheel goes up the seat goes back all electronics turn off and the radio little red led flashes and the coolant fan will occasionally go full speed.
Steps i I have taken so far:
Searched for hours found a simmilar issue but they were having no start no run bad ecu. My car runs and drives very smooth.
I replaced the crappy salavge yard battery the PO had in it with a proper H8 group 49 battery.
can someone please explain what the heck is going on and what I should check next? I'm rather mechanically inclined but this is so bizarre to me. I was thinking it's the ICM but the key locks unlocks car, the steering wheel, and starts it just fine.
Please help!!
Last edited by ninjaff21; Mar 15, 2017 at 06:16 PM.
being everything works with the motor off I'm not sure what could be the issue. its literally as if when you turn the motor on you turn the car off. never have had an issue like this before
Update: the stepper motors are all working in test mode it seems like one is clicking though. i can't use the controls to control the vents though it seems to be stuck on the floor.
Update 2: the vehicle was most likely jumpstarted with they key in the ignition last night. i am a used dealer bought the car at auction most of them are flat batteries. not sure if it was jump started or not.
Update 3: key is now hit or miss if it will actually turn in the ignition or not.
Last edited by ninjaff21; Mar 10, 2017 at 11:04 AM.
Code P0600 is communication failure code - a computer (like ECU, TCU, EIS, etc,...) could have failed or gave BS signal or something - check all grounds to ensure they're good and check wiring for any damage. Ensure main wiring harness at ECU isn't soaked in oil! Any sign of oil leaking anywhere in engine bay?
When computer fail or communication fail, modules don't get their expected signals or any signal at all. IE: Front radiator fan control module don't get signal so it automatically goes into high turbine mode like a jet engine - that's it's default safety state! It does that incase if the engine's on fire or overheating - to protect the engine.
Clear P0600 code and restart. Try to get a different code!
If you're very good at diagnosing electricals, you could access CAN-BUS wiring under driver's front door sills near front and tinker there to try to figure which signal is missing,.... otherwise, it's best to leave that to a pro!
Mercedes are really fussy about battery. Only use OEM Mercedes-Benz car battery! Aftermarket battery are usually underpowered - not enough Amps - need 100Ah.
That said, it's possible but not likely for an aftermarket battery to somehow affect one of the computers which would trigger a P0600. It's better to just drop in a OEM Mercedes Battery and start diagnosing from there. Electrical stuff are a pain to diagnose and something like an aftermarket battery won't help.
Speaking of aftermarket, does the car have any other aftermarket (non-stock) electrical add ons,.... like aftermarket HID lighting, stereo, etc,... something where the wiring is questionable,...
When installing the new OEM Mercedes-Benz car battery - do follow the procedures in the manual perfectly, otherwise it's very easy to damage the Front-SAM.
2012 Genesis Sedan, Whatever Benz i have at the time
Do these symptoms sound like a bad Sam to begin with? I feel like the auction jumpstarted it wrong or the people before just kinda messed it up with their to small junk yard battery?
2012 Genesis Sedan, Whatever Benz i have at the time
I would like to add that when the engine is running brake lights work headlights can be controlled and tail lights work but signals do not. Those are the only controllable working electronics when the engine is running and I can turn the radio on. Like I said it just like if the car is off. I believe I can open the trunk also.
Did this car ever work properly for you? Or did you buy it at auction as it is now?
With electrical issues, you want to get the car back to stock or as close as possible,.... that includes new OEM Mercedes-Benz battery. Regardless, that's the battery you need in this car. Once that's done, we'll know you have the proper battery with real juice in it and then we can start figuring things out.
After that you want to hook it up to a real code scanner (ideally MB Star DAS) but at least something that'll give you a real log of what's going on when you try to start. Right now, you're only getting P0600 Communication Failure - which is the latest error code after the car gives up, but what is triggering it! You need something that'll read a log!
2012 Genesis Sedan, Whatever Benz i have at the time
Yes it worked properly on my test drive. Then after I brought it back said all was good and paid I went out it started right up no issue but the issue instantly happened then. When it was in the parking lot I could turn the key and it not start but electronics worked I assume dead battery and the auction jumped it.
I would like to add that when the engine is running brake lights work headlights can be controlled and tail lights work but signals do not. Those are the only controllable working electronics when the engine is running and I can turn the radio on. Like I said it just like if the car is off. I believe I can open the trunk also.
How does Signal not work? Both left and right don't work? And both front and rear don't work? If so, that could be a signal switch issue. Which is relatively common problem.
2012 Genesis Sedan, Whatever Benz i have at the time
ordered a new key and picked up a mercedes battery. battery changed nothing. looking at the front SAM i pulled a few fuses and they were very burnt/corroded. I'm going to pull the front SAM and clean it with contact cleaner. Maybe replace the fuses. With the ignition off fuses 43-52 do not have power. also when looking at the diagram my car has a relay that isn't on the diagram???? i attached a picture to this post. there is the 2 relays with the 3 under it. mine has 3 with 3 under it.
Good, now that you have the proper OEM Mercedes-Benz battery installed, we can eliminate that as a problem.
I assume, you never got a second key? In which case, ordering a 2nd is always a good idea.
Why are some of the fuses in the Front SAM appear corroded or burnt? Was this a flood car? Or blocked water holes near Front SAM area and battery compartment causing corrosion issues?
I wouldn't worry too much about the "extra" relay. Some cars have them, depends on which options and trim level you have.
After you get FrontSAM cleaned up. If it still does not work, then start testing relay. Here's how I "test" relay. Not ideal but easy! Uniquely number relay and up direction then with KEY OUT! - switch similar sized & colour relays around (FrontSAM and rearSAM if needed). Then try to start, if it doesn't work then with KEY OUT, switch them back and try another pair,.... https://mbworld.org/forums/c-class-w...ml#post5202308
2012 Genesis Sedan, Whatever Benz i have at the time
Ok to update you more on the SAM i have pictures I'm going to upload. IT CLEARLY HAS JUNK YARD MARKINGS!!!!! I'm going to try cleaning it and testing relays like you have said. Could this all be caused by the not so bright previous owner not coding in the junk yard SAM? if you saw the dealers i bought it from at auction you would assume they had no idea about the car. An uncoded or bad junk yard sam would explain a lot of this in my opinion. also most junk yards leave hoods open ETC. which could allow for water to get in explain all the corrosion.
While removing the sam i also removed the ECU. as i hear a blown ecu will have rattling. the ecu does not rattle but has a small dent in it.
CORRECT ME IF IM WRONG: the sam in my car is part number 209 545 00 01
pelican parts says the correct part number for my c240 is 203 906 00 05
if I'm correct the sam i have here in my hands is for a CLK (w209) not a c class (w203) like i said correct me if I'm wrong. but from what it looks like my car has the completely wrong part number currently in it!
Last edited by ninjaff21; Mar 13, 2017 at 04:21 PM.
2012 Genesis Sedan, Whatever Benz i have at the time
More photos from my wire inspection also: i found these wires twisted together i can't tell which harness they come off of though. also these random wires that have been put back together.
Most blown ECU will NOT rattle! My ECU rattled because chrystal-oscillator fell off circuit board due to bad solder joint and vibration over time. But if I had shaken it before taking it to my Indy, I could have fixed it myself and saved lots of money too!
Any of these front-SAM part numbers should be fine for 2002 C240:
2039060005 ; 2035454201; 2035450601; 0025459401; 2035455001; 2035453001; 2035452801; 2035451001; 2035451601; 2035454601; 2035453601 http://www.mbpartsworld.com/p/Merced...039060005.html
W203/CL203 (c-class sedan/coupe) and W209 (CLK-class) share many parts. That said, the A2095450001 isn't on the list of Front-SAM for 2002 C240 as per above www.mbpartsworld.com site. In addition, I can't fine A2095450001 on www.mbpartsworld.com site. A google search of that part return mainly ebay listing from europe - maybe it's for right-hand drive CLK?
You might want to drop my the parts department of your local Mercedes-Benz dealership to inquire is A2095450001 is compatible with your 2002 C240.
As I recall, Front-SAM for our generation of W203/CL203 needs to be variant coded, not VIN-coded but matched to your cars options/accessories, thus giving the dealership your VIN# would be helpful so they'll know which variant to use! I don't recall Front-SAM requiring SCN-coding (coding between EIS, ECU, TCU, and other computers so they're introduced to each other)
With all these wiring connection the previous owner/mechanic did, you'll need to find a wiring diagram OR a Mercedes-Indy mechanic that specialize in Mercedes electricals.
Last edited by SunnyRayToronto; Mar 13, 2017 at 09:45 PM.
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