Help! – 35d Randomly dies with DSC & X-Drive malfunction warnings displayed

[Best4x4xFAR]

So this started about 3-4 days ago. My wife was sitting in a parking lot in drive, with her foot on the brake, and the engine just died, with a host of DSC & xDrive warnings on the iDrive screen, and the traction control (yellow) ‘BRAKE’ and 4x4 warnings in the instrument console. A simple turn off and restart seemed to be fine, all warnings gone, engine started with no issues.

The next day she was coming to a stop and it did the same thing, but shifted into neutral as well as she was still moving. Press the start button and it restarted, warnings all still illuminated, shifted into drive and off she went. When safe to pull over, she did, and turned it off and restarted, all warnings gone, truck started normally.

But then she was driving along at about 35-40 mph and the same thing happened. Luckily there was a safe place to pull over. Again, turn off and restart with no issues.

So I pulled the codes with a Foxwell. There are some engine related codes I am already aware of (EGR plausibility, SCR efficiency, DPF nearing end of life, and a bad glow plug), but this is what is new, and the online sites I usually look coeds up on have little if anything. Searches of Bimmerfest, xOutpost & Bimmerpost/xBimmers don’t seem to be turning up much.

I did find this thread (https://xoutpost.com/bmw-sav-forums/...s-dsc-etc.html) that has similar symptoms, but far more acute I guess, and we haven’t had any major rain storms, or signs of water in the interior of the car. My wife did have the car washed at our local BMW dealer the day before this started however. I guess I should take the cow apart and make sure it is dry down around the DME, maybe one night this week if I can get out of work early enough…

Anyway, there are multiple errors that seem to be related to communication failures between modules?

Truck has 140K miles on it, Battery was replaced with a BMW branded 105AH AGM battery 1.5 years/23K miles ago. I changed the oil and filter and cabin filters 3 days before the issue started. Doubt that is related, but it is all that has changed since the issue started.

Hopefully someone has experienced this?

[andrewwynn]

Bus controlled modules with multiple failures suggests wiring problem like a damaged harness or connector that affects multiple items. Not sure where I would start looking was there work done not necessarily recently that wiring loom may have been affected the common example is somebody pinched a wiring harness in the valve cover


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[Best4x4xFAR]

For those who are interested and/or following along, for the last week the car has run without issue. It rained fairly heavily on Saturday (and the car both sat in the rain for some time as well as was driven in the rain that day, again without issue, as well as on Sunday without issue. Then yesterday it acted up again, dying on my wife multiple times.

I pulled the cows, HVAC Filters and took the top off of the ECU Box, and I see no signs of it being wet in there. None of the wiring harnesses felt like there was any diesel fuel on them, nor had any odor of diesel. So I’m really hopeful it is neither the infamous diesel in the DDE nor a water leak issue (unless it is affecting another component?).

Checked the codes, and the “2121 DDE: DDE Main Relay" returned. So I have ordered a DDE main relay (light blue) and a Multipurpose (Green) Relay from FCP Euro for replacement, figuring the Green relay may not be far behind if the blue one is failing (Hopefully these are correct, I had to email FCP support as I couldn't find them on the site and They sent me these links. they look the same, but my year/model is not listed in the description?!?)

Really hopeful this is the issue..

There was a fair amount of ‘leaf’ debris at the bottom of the fender well (under the DDE box), and with some creative extensions I vacuumed it out from both the passenger and driver sides. Everything that came out of the area was bone dry, so again, hopefully this is a sign there has been no water back-up issues in the area..

So for replacing the Relays, I’m assuming disconnecting the battery first is a good idea, but anything else to look out for in the process?

P.S. – What is this flat box bolted to the inner fender next to the DDE box? I searched the part number on the face of it on FCP Euro and it comes up as an ‘Insulation housing Fan Connector’? What exactly is that, and what is it’s purpose? Given how cheap it is, I’m assuming there is another component inside, but in general, what is in there and what does it do?

[Best4x4xFAR]

Update, if anyone is following along..

Replaced the DDE Main relay, apparently wasn't it. Oh, and I lost the FWM, after disconnecting and reconnecting the battery, but luckily was just under the extended warranty and the dealer replaced it). Car seemed to be doing well for a week or two.

Then my wife and I went to the beach, and it stalled once when we got there (And I thought oh great, 170 miles from home), but restarted fine. No new codes (yeah, I keep the Foxwell in the car), but the DDE main relay came up again.

Next day, we stopped for breakfast, and it wouldn't restart. Pulled out the Foxwell, and can't even communicate with the DDE now. This was the beginning of a 9 hour ordeal to get the car back home (Luckily I have AAA Platinum which covers on 200 mi tow, mainly because I own a classic Land Rover, never thought I'd have to use it for the BMW)

Thank you BMW for programing the transmission NOT to go into neutral unless the engine is running, and for the cruel joke to include the red handle tool for putting the car into neutral, even though you no longer provide the access under the cup holder. My wife eventually located tools from a local store owner and I was able to eventually remove the plethora of underbody panels and put it into neutral to get it onto the tow truck.

Pulled the ECU, and sure enough module 4 has a sheen and odor of diesel. So after the stuggle of getting the case cover off the DDE (so much adhesive, its ridiculous)...

So I cleaned the DDE board with Craig Labs DeOXIT DN5, multiple times over several different days, with at least 24 hours in between for drying and light compressed air application tol remove any excess.

Cleaned the harness back to the entry point of the DDE box multiple times with WD40 Contact cleaner..

Cleaned the connectors in the same manner with the WD-40 contact cleaner first, then the DeOXIT DN5..

Reconnected everything, reconnecteds the battery, and truck started right up. Let it idle for maybe 30 minutes, no drama. Cleared all the codes with the Foxwell.

Taken it on a couple of short trips without issue, but I'm affraid to drive it, seems many have cleaned it in a similar manner, only to have it leave them standed. I was supposed to be making a 40+ hour round trip drive in August, thinking of Turo'ing something for the drive at this point.

Don't know how much driving to do before I can be confident it is not going to leave me stranded..

Still have to replace the source of the issue as well. For now figure I'll check the DDE harness weekly for any signs of diesel and clean as needed.

Really hoping I don't need to purchase a new DDE. Is there some sacrifice the BMW gods prefer?

[andrewwynn]

If diesel is wicking though the harness cut the bundle sheath off for a couple inches you can stop it from getting into ECU. I forget the source if that happens.

The same type of problem happened to me with e53; water wicked from under the hood through the cable to the transmission!

[ard]

Originally Posted by andrewwynn

If diesel is wicking though the harness cut the bundle shath off for a couple inches you can stop it from getting into ECU. I forget the source if that happens.

The same type of problem happened to me with e53; water wicked from under the hood through the cable to the transmission!

Is the root cause an internal seal failure at the high pressure injector, letting fuel up through the electrical contacts, into the connector and inside the cable sheath?


It seems to be not unheard of...not common, but not 1 in a million. Ive read of a few over the last 10-12 years.

[andrewwynn]

I don't remember how rare butt I've heard of it at least 1:1,000,000


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[Best4x4xFAR]

Originally Posted by ard

Is the root cause an internal seal failure at the high pressure injector, letting fuel up through the electrical contacts, into the connector and inside the cable sheath?


It seems to be not unheard of...not common, but not 1 in a million. I've read of a few over the last 10-12 years.

Similar, it is a seal failure in the fuel pressure/temperature sensor..

Still dying randomly, so I guess I'm going to need to source and have cloned a new ECU...

[Diesel Spectre]

I have read the fuel temp/pressure sensor is the culprit as well if you find diesel wicking into the dde.
Conversely, I had a similar issue without the fuel wicking problem that turned out to be engine grounds.
Hopefully you have it sorted by now.