[Ironslide]

Vehicle: 2008 335i n54

Car has no power unless cables are actively jumping the car with a max voltage of 11.5V(measured through OBD/MHD app). Absolutely zero electrical response if the jumper cables are removed as if the battery drops to 0V immediately. I have to run out to get a new multimeter so I cannot directly test any fuses or the battery directly yet. Car was last ran two months ago with no issues.

As soon as the jumper cables are applied, the waterpump starts running at fullspeed. This continues until the jumper cables are removed.

The fault codes are:
2AB4 - DME: DME, internal fault: RAM checksum
2ACB - DME: DME master relay, activation
2ACC - DME: DME: master relay, shift delay
2C73 - DME: Oxygen sensor after catalytic converter
2C74 - DME: Oxygen sensor 2 after catalytic converter: signal
2D09 - DME: THROTTLE
2D1D - DME: Accelerator-pedal module, pedal-position sensor 1, voltage supply
2D1E - DME: Accelerator-pedal module, pedal-position sensor 2, voltage supply
2D1F - DME: Accelerator-pedal module, pedal-position potentiometer, signal
2DEC - DME: Power management, battery
2E7C - BSD data bus Communications fault
2F4A - DME: Interface EWS-DME
2F63 - DME: Brake-light switch, plausibility
30BB - DME: Injectors 4,5,6 or DME, internal fault

Injectors were done a year ago to latest index and would be a symptom rather than the cause. All other posts I have found detail some of these codes and point to either MOSFETs fried, fried DME, bad battery, bad B+ cable, bad relay (either in ebox or fuse box). All other posts list different fault codes.

Not sure the best path forward. Looking for some advice. New battery, new relays, test fuses(F1-5? all?), new DME?

Edit: Recall work for the blower motor was done over a year ago. 1-2 days after this job A/C vent air smelled like burned plastic. The battery cable recall was done a few years ago (do not recall how many years). I read somewhere that the B+ cable type was changed in recent years.

[Emilime75]

Originally Posted by Ironslide

Vehicle: 2008 335i n54

Car has no power unless cables are actively jumping the car with a max voltage of 11.5V.

Please explain this a little better. What and how are you measuring 11.5 volts?

Originally Posted by Ironslide

Car was last ran two months ago with no issues.

Very likely the battery has just crapped out.

Disregard all of the fault codes for now, these cars go hay wire when voltage drops.

[Ironslide]

Originally Posted by Emilime75

Please explain this a little better. What and how are you measuring 11.5 volts?

Through OBD on MHD app.

[stewbets]

Yeah, it sounds like the battery was completely drained over the last couple months and is toast. I would put it on a charger at a 10 amp or so setting overnight and see what happens in the morning. It's likely ruined. Are you able to start the car with jumper cables connected?

[feuer]

30bb is burnt ecu. Car should run without battery if alternator is ok.

[Ironslide]

Originally Posted by stewbets

Yeah, it sounds like the battery was completely drained over the last couple months and is toast. I would put it on a charger at a 10 amp or so setting overnight and see what happens in the morning. It's likely ruined. Are you able to start the car with jumper cables connected?

It is located on the street. I have not used a battery tender/trickler before, though it is a good idea to get one. Is it possible or safe to squeeze one with the hood closed(latched)? Thinking about replacing the battery regardless due to its age.

Would not start. Dashboard would flicker, and slight start noise (less than .2 seconds) cannot tell if it is starter or if it is fuel pump priming not too certain. All other electronics were functional such as door locks, windows, etc. (did not check radio) while being jumped.

Originally Posted by feuer

30bb is burnt ecu. Car should run without battery if alternator is ok.

Probably accurate. Turns out I have an MSD81 ECU rather than MSD80.


I found this thread: https://www.e90post.com/forums/showthread.php?t=1585293

Since it is a 2008 build I think this is the right diagram:
https://www.newtis.info/tisv2/a/en/e...supply/vMifIQL

Hopefully my pins are only slightly corroded which is causing this. Any tips how to determine pin locations? Linked thread is a different build date not sure if its the same regardless. Some additional posted codes as well.

[Ironslide]

Update:

Tried a new battery, managed to peak at 14V. Car cranked this time, struggled to start. Managed to get to a rough idle for a few seconds on one attempt. Turned off, tried a few more times similar or worse results (sometimes did not start). All codes returned after first reset attempt. Could this have done any damage?

Disconnected battery. Removed all connectors and ECU. Turns out I have an MSD81 ECU with an early 08 date on its sticker. This eliminates the common MSD80 MOSFETs ordeal.

Decent amount of pooled water near connectors 6 and 7. No other signs of moisture in other areas. Inspected all male/female connections. Wires looked to be in good condition, some pins looked damaged(?). Attached a lot of pictures of both the male/female connectors and the ECU itself. ECU connector interface was pretty wet. Other connectors appeared to be dry. See below for all pictures:

ECU board was wet as seen in one of the pictures. I placed it in a bag with a rice bed and placed some silica bags on top of the exposed board (small holes would allow rice to fall in) to absorb moisture.

I am looking to buy some canned air and contact cleaner (multimeter on route). How should I go about cleaning the contacts/pins or testing resistance? I did not see signs of burning, does the ecu look okay? I believe connectors 1 and 2 are the main culprits which may be triggering the others to fault. I do have two different ideas how the water ingressed in the first place and will address in a future post, but first I would like to determine if this is salvageable and to what degree.

Any one have any input or better ideas?

[Ironslide]

I must have forgotten to take a picture of connector #6, but I do not remember seeing any signs of damage/corrosion. #7 appears to be a 50 fuse.

[Ironslide]

2 broken pins on the ECU. Will have to check if they are still inside the female connectors. If they are stuck, what is the best way to remove them?

Looks like a new ecu is required. Do the other connectors look salvageable?

What is a reasonable repair quote for a dealership or indy/used dme/programmer?

[Emilime75]

That's not looking good. Have you identified how water got in there? Are the cowl and DME cover in place and installed properly?

[Ironslide]

Cowl and cover were on properly. One possible ingress location is through the ECU fan port or the other is that the cable was not aligned or seated all the way (see picture). Both are extremely unlikely. The cabin has moisture build up which I assume is either from the windshield molding or something to do with the sunroof, which would lead to moisture exposure in the glovebox. Neither of these should be possible. When I pushed the backseats down I noticed some water where you hook up a child safety chair.

I am trying to gauge the scope of this repair before sending the car off. Think cleaning the connectors and a new ECU would be good to go? Anything else? Downstream electronics?

[Emilime75]

It's hard to tell from the photos if cleaning the connectors will suffice or if you'll end up with intermittent conductivity issues, may need to repin/crimp new in place of the rusted/corroded ones on the harness plugs. Again, can't quite tell if any of the DME pins are salvageable.

No way of knowing right now if any other modules fried. Not sure if DME can be repaired, probably better of with a clean replacement.

But, I think if I was in your shoes right now, I'd fix all of the connector issues, clean the DME circuit board with alcohol and De-Oxit and Q-Tips and have a good close look to see if any components are clearly burnt.

If things look OK, plug stuff back in and see what happens. Not much to lose at this point, and maybe you get lucky. I've brought back to life other various electronics that had gotten wet and failed by cleaning the corrosion from connectors and circuit boards, you never know.

[Ironslide]

No deoxit on the DME circuit board, correct? Would a nylon toothbrush be good enough for the pins? I have a copper wire brush but it might be too rough if some of the pins are already weakened.

There are 2 contacts broken off the DME circuit board, they are broken near the base and corroded. They appear to be molded into the housing. I am assuming it is not feasible to get a replacement housing/contacts for the DME? It is looking like a new DME/reprogramming (stealership time) is required at some point. I also have to get the broken contacts out of the female connector. What is the best way to do this? How to release the contacts from the housing? Would it be worth trying to recover the broken contact ends and attempt melting them back together?

Going to have a crack at cleaning and reconnecting. Hopefully I can still troubleshoot some of the other modules with a partially connected DME.

Assuming I can communicate with the DME through INPA, how would I access status of modules?

[Emilime75]

I see no problem using De-Oxit on the board, but from your description of the pins on the DME, it might just be toast so no need to worry about it. Maybe you could find a used/dead DME and transfer over the connectors, but you still don't know if yours is any good...which brings me to a used DME, is it not possible to recode a used DME to your car?

[Ironslide]

Is it true that the DME, CAS, and key(s) need to by sync'd (programmed)? Is it an issue if old DME is bricked? What steps or tools are needed? Does car series matter (for example a 5 series n54 MSD81 DME for a 3 series CAS)?

[Olo7109]

Originally Posted by Ironslide

Is it true that the DME, CAS, and key(s) need to by sync'd (programmed)? Is it an issue if old DME is bricked? What steps or tools are needed? Does car series matter (for example a 5 series n54 MSD81 DME for a 3 series CAS)?

Originally Posted by Ironslide

Is it true that the DME, CAS, and key(s) need to by sync'd (programmed)? Is it an issue if old DME is bricked? What steps or tools are needed? Does car series matter (for example a 5 series n54 MSD81 DME for a 3 series CAS)?

wondering if you got anywhere with this? I'm having same codes 2acb and 2acc, going into the JB and EBox on Monday, weather permitting to check for water and corrosion, which I assume I'll find, since every fuse I pulled from the front of the JB had corrosion on the connectors. did any of yours have the same issue?

this is all new to me, so I was hoping for a good outcome on your end because it could give me a glimpse of hope to have more than crank, no start.