SL65MONSTA

Problem: Check Engine Light - Driver Side Bank, Shows all 6 Cylinders misfire, with a code showing P0300 as Random Misfire as well, no other codes.

Work already did - All Spark plugs, OEM Bosch Platium Iridium, 24 of them, Iginition Coil Pack Driver Side (New Mercedes), Fuel Filter Changed (was kinda stuck), Check out the catalytic Converters, compared driver side and passenger side, looked the same, not plugged or anything, pretty clean, swapped Oxygen Sensors from Driver to Pass.,




The ignition module in the center of the engine can go bad cutting out power to the driver's ignition coil pack

Mercedes Tech Guy:
Its not really a module but a DC to DC converter

Mercedes Tech Guy:
It steps up the voltage from 12 Volts to 120VDC.

Mercedes Tech Guy:
Also, make sure no oil is in the wiring harness connector for the driver's ignition coil pack. Just want to make sure you know that is for cylinders 7-12

Customer:
yes, the misfires say cyl. 7,8,9,10,11,12, and the P0300

Customer:
also can you let me know how to check the ignition module?

Customer:
is there a picture of it?

Customer:
i just want to know if it is bad before purchasing the part, is there a way to find out?


Its module right in the center of the engine

Mercedes Tech Guy:
I'll check the wiring diagram so you know what power wires to check going to the coil. All this module does is step up the voltage for the ignition coil pack

Mercedes Tech Guy:
Ok, there is a red wire with blue tracer that goes from the ignition unit to each coil pack. Check the voltage by backprobing the connector on the ignition unit. You should have the same voltage for both wires.

Mercedes Tech Guy:
Then there is a red wire/green tracer and red wire/grey tracer coming out of this module, both of them should have the same voltage also.

Mercedes Tech Guy:
One last check, the red wire/brown tracer and red wire/yellow tracer should match in voltage as well.

Mercedes Tech Guy:
If one of the voltages is off, the ignition unit is bad.

Customer:
check this with the car running?

Customer:
ignition on or off?

Customer:
i am sorry, a total of 4 wires you are saying that should match the same voltage right?

Customer:
i see three wires with red/blue, two of them are closer together, with thicker blue tracer, and one farther away with a thiner blue tracer

Mercedes Tech Guy:
Checked with the car running

Customer:
does it say how many voltage these wires supposed to have?

Mercedes Tech Guy:
The thinner red/blue wires should have the same voltage. The thicker ones are the inputs

Mercedes Tech Guy:
No I don't have that spec with me but if one side is going out, the voltage would drop out on the driver's side one

Mercedes Tech Guy:
You can just compare the same signals that are sent to the left and right coil packs, since they should match

Mercedes Tech Guy:
If they don't, then you know the ignition module is bad.

Mercedes Tech Guy:
A total of 6 wires you should be checking

Mercedes Tech Guy:
red/blue are a pair

Mercedes Tech Guy:
red/green and red/gray are another pair

Mercedes Tech Guy:
red/brown and red/yellow is the last pair.

Customer:
got it i will perform the work and find out, but is it safe to poke the wire since its a 120vdc??

Customer:
will the electricity jump and short something out?

Mercedes Tech Guy:
No, just don't ground anything out. That voltage won't jump, you

Mercedes Tech Guy:
You're thinking of 40,000 Volts of normal ignition spark voltage....that will jump

Mercedes Tech Guy:
Where rubber gloves when doing the tests also

Mercedes Tech Guy:
Or some sort of insulated gloves, just in case your test leads are poor.

Customer:
i shall let u know the results shortly

Mercedes Tech Guy:
ok

Mercedes Tech Guy:
Is the problem happening currently or intermittently?

Customer:
the problem is currently there, and it wont go away, just a few throttle play, the check engine light is there

Customer:
i just measured the red/blue wire set, here is the finding, the two red/blue wire w/ thicker blue tracer read 13.8, and the red/blue wire with thinner blue tracer read 10.7

Customer:
does it mean the module is bad?

Mercedes Tech Guy:
you mean the thin tracer line, not the thinner wire?

Customer:
tracer line yes

Customer:
not thinner wire

Customer:
basically there are 3 red/blue wires, two of them are right next to each other, and the other one is farther away and looks like the blue tracer is thinner

Customer:
the thinner tracer one reads 10.7

Customer:
the ones right next to each other read 13.8

Customer:
does it mean module is bad?

Mercedes Tech Guy:
No, how about the other wires?

Customer:
i am still checking

Mercedes Tech Guy:
Sorry, my colors are wrong, I had a 2002 in my wiring diagram on accident

Mercedes Tech Guy:
I know you have the 275 twin turbo engine

Customer:
what's the correct colors?

Mercedes Tech Guy:
the red/blue are correct

Mercedes Tech Guy:
red/grey tracer and red/green tracer should match

Mercedes Tech Guy:
the red/black tracer should match the other red/blue wire with the 10.8 volts

Customer:
i c

Customer:
let me test them and get back to you

Mercedes Tech Guy:
ok, sorry

Mercedes Tech Guy:
red/ yellow tracer should also match red/ brown tracer

Customer:
so a total of 4 pairs

Customer:
is it cool if i can get back to you on Monday on the vol match outcome?

Mercedes Tech Guy:
Yes

Customer:
i have completed the test, and here are the finding, please review

Customer:
red wire blue trace - 13.4

Customer:
red wire grey trace & red wire green trace - 13.4

Customer:
red/black & red/thinner blue trace - 177

Customer:
red/yellow & red / brown - 22.8

Customer:
they all match

Customer:
what is next step?

Mercedes Tech Guy:
Is the car actually misfiring right now, though?

Mercedes Tech Guy:
Does it misfire right away or after driving awhile?

Mercedes Tech Guy:
If it doesn't start misfiring until after you drive it awhile, you may have to drive it and then immediately test the voltages

biker349

very interesting. i had a similar problem and the tech checked the coils and said they were good. he pulled them. guess he looked for discoloration, or something on the coils. some how he found an intermittent fault in the transformer and replaced. solved my problem. don't know how he checked it, unless he somehow eliminated the coil packs as the problem. he also checked the spark plugs which were good.

SL65MONSTA

Might be the same guy hahaha , some mercedes dealership stories I've read on here replace coils, IGN modules , sensors , etc to diagnose a misfire. How the hell does this guy not put his info into the Mercedes Dealerships manuals? wouldn't that save them thousands in warranty parts and throwing out good coils they might misdiagnose as faulty ?

Really some things just seem to amaze me

ZephTheChef

Makes sense to me. But I still am wondering if the "ignition module" is all internal to the coils. That test/those voltages pretty much confirm that the box in the middle is just a dumb voltage booster that supplies primary voltage and has little to do with triggering coils/spark logic. But there are certainly enough wires on the coil pack for external triggering. I still haven't messed around with trying to map out the coil/connector. Have WAY too much else on my plate right now.

ZephTheChef

Cross-posting this from the other thread to be more search friendly:

SL65MONSTA

Something I haven't figured out yet, how do you insert the probes of the multimeter to get readings? I have tried so many times still getting no readings, I dont wanna cut into any wires

ZephTheChef

There are all kinds of back-probe/lead kits available for most multimeters.

SL65MONSTA

I've soldered onto my probes long sewing needles , that is the only thing you will ever get into the wires inserts to do the test, and pray to god they dont accidentally touch each other. Word of advice wear rubber gloves , were talking 180v it rattled me !

ZephTheChef

Lol. Yeah, even 12V will get you if you've got sweaty arms and lay across a battery. 180V is just plain dangerous. I was shocked they didn't have that wiring wrapped in orange warning sleeves like all the hybrid cars do.

SL65MONSTA

help me out with one thing here the tech guy mentions the first pair to test but only says one wire description, what would be the other wire to probe onto ? he mentions
Customer:
red wire blue trace - 13.4 >>>>>>> However what is the other wire to put the probe to?

Customer:
red wire grey trace & red wire green trace - 13.4

Customer:
red/black & red/thinner blue trace - 177

Customer:
red/yellow & red / brown - 22.8

ZephTheChef

Just make sure the same function wire reads the same side to side. That was what the Mercedes tech was getting at. And if the car isn't misfiring they will. And if it is misfiring, I believe the car will quickly shut down power to that bank anyway. So I'm not sure if it's really a helpful test.

SL65MONSTA

Tests come back fine, I think its probably the right side coil pack bank. I like not driving my car for a couple weeks , when you get back in she feels like a whole new beast! similar to my girl I cant see her everyday I get sick of her and do crazy things to her, similarly to people who get bored on here and buy stuff for there car not needed haha

LynnBilodeau

For what it's worth, I had the exact same codes on my wife's CL600. All 6 driver's side cyl went down. Pulled the coil pack and put in a used one. All six still misfiring. Replaced the ignition module and three were misfiring. Put my old coil pack back in and it has run perfectly since doing so.

I am determined to find another ignition module to carry in the car along with a few tools. Could easily be changed out in an emergency.

Also figured out (and later confirmed) that both coil packs had been previously replaced with the upgraded ones.

Did find a place where I could send my old ignition module for repair.
Here: http://www.ebay.com/itm/281365680102?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

SL65MONSTA

i found out what my issue was, just waiting for it to arrive soon, thanks for the comments

SL65MONSTA

Okay I still haven't found out what my issue was, had the coil pack rebuilt still misfiring on cylinder 1,3 and 5 I am going to try to get a Voltage transformer see if that helps, did your car go okay after replacing the module ?

LynnBilodeau

Has run perfectly since replacing the module.
When I replaced the plugs, I could tell both coil packs have been replaced. Confirmed this by checking old service records.

SL65MONSTA

Replacing the IGN unit is my next step this is really silly that we need to replace items that may be working just fine.

_Ryan

The trouble with checking voltages is that most problems show up under heavy load. Voltages could be fine at idle or even at 30% load and 4k rpm and you can still have an issue at 50% load. Unfortunately, the best way to eliminate the voltage transformer is to put a new one in and see if the problems goes away.

Plugs and coils are typically the problem but you already did that. There isn't much left to the ignition system. In your case, I would absolutely swap the transformer and see what happens. I would not go with a used one. Too many issues.

SL65MONSTA

yeah STAR Diag should be able to log this fault and tell you instead of replacing parts randomly. Thanks for heads up

bbbc78

I feel like my problem is very close to yours. My car will intermittently run awesome and sometimes the drivers bank is completely dead. I first had problems with my car not starting when hot and my car finally threw a CPS sensor code which made since why it started dying on me after driving it. So that has been changed and i also did the drivers coil and switched out the transformer and spark plugs. Its runs great with no misfires when the drivers bank works. Then its just the whole side dead next time i start it. Do your guys have any ideas??

Its been in the shop now for over a month and i have a feeling i will be getting it back not fixed or i will go to the shop and help speed things up.

Thanks

ZephTheChef

When a whole bank is down, it is supposedly an overload or short problem with the output stage of the voltage transformer, which could be an issue with the transformer itself, or a short in the wiring/coil on that side causing that problem. Did you put a new coil and transformer, or used?

bbbc78

I have tried 2 different packs and transformers from clark at v12icpack.com. Both were tested and working on his s600. His is not a biturbo but everything worked as it should. My mechanic is leaning toward wiring but its been over a month so he is probably just guessing like i was. We both have star diagnostics and it shows the the pack is shutoff before even starting the vehicle sometimes.
I appreciate the response and any advice. This has been quite a process and my car needs to be smogged next month.

Robkatts

May be a bad Ground.
Make sure all is grounded to engine, then check engine to frame, Frame to Neg Battery.
Worth a shot.
When i had trouble with voltage transformer i lost one whole bank. It looked good inside, but was lacking voltage on one side.
Their is a Clark guy that fixes them out of CA.
Hope this helps
Rob

bbbc78

Where are the grounds to each side your talking about? I thought the pack grounds to the block with the whire coming off the harness. Did you get a new transformer to solve your issue?

thanks

Robkatts

There are ground wires on each side of coil packs and the transformer, check them.
What u describe can be bad ground. if u don't have them make your own.
Ground is very very important.
When i lost one bank of coils, i tested for voltage in and out, on each side and one side had no voltage out.
I was going to go with Clark but the shipping back and forth i had no time.
So that is when i got one from MB Online New.
Fix it .
That Clark guy is a good ****, but used rebuilt parts are used rebuilt parts,and this car is more space ship then auto.
Good luck