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?

[jbash87]

Hmmm. These are really tough.

Although not exactly your symptoms the exact symptoms seem to vary quite a bit.
Check your ground straps

[Best4x4xFar]

I pulled the cow/cabin filter housing and opened up the ECU housing (damn that was a pain), and it is dry as a bone in there. Looked around with a flashlight for an hour, I can't find any signs of damaged wires under the hood. I need to find all the ground strap locations and check them next, I ran out of light tonight..

[RL18]

Originally Posted by Best4x4xFar

I pulled the cow/cabin filter housing and opened up the ECU housing (damn that was a pain), and it is dry as a bone in there. Looked around with a flashlight for an hour, I can't find any signs of damaged wires under the hood. I need to find all the ground strap locations and check them next, I ran out of light tonight..

Take a hose and drizzle water down that side of the windshield and make sure your passenger side fender drain is draining and not clogged. Mine was clogged and would flood my dde box, but after rain would dry up as if it wasn’t happening.

[Best4x4xFar]

RL18, I was concerned maybe I had reinstalled the cow piece above the cabin filters and DME wrong, and this allowed water to get to the DME, but that thing is in quite the sealed up box, and when I eventually got into it last night, it was dry.

Its been dry for days here, and it is still doing it. Quite random, may make a couple trips and it doesn't happen, may make another trip and it happens a couple of times.

I really have no idea how I'm going to track this one down, say a prayer for me..

[RL18]

Originally Posted by Best4x4xFar

RL18, I was concerned maybe I had reinstalled the cow piece above the cabin filters and DME wrong, and this allowed water to get to the DME, but that thing is in quite the sealed up box, and when I eventually got into it last night, it was dry.

Its been dry for days here, and it is still doing it. Quite random, may make a couple trips and it doesn't happen, may make another trip and it happens a couple of times.

I really have no idea how I'm going to track this one down, say a prayer for me..

The water damage could of already been done to the dde then. The dde box isn’t completely sealed off. It has vents, so if that drain I showed in the picture above gets clogged that whole section will fill with water eventually working its way into the dde box. That whole piece is actually completely sealed off the the fender liner, mine was torn up in that picture from me removing it. It’s completely worth checking if the drain is cleared even if it’s not the issue because eventually it will most likely happen.

It’s actually a pretty simple job. Remove tire on passenger side. Then you need some fender flare rivets, a rivet tool, drill and a drill bit (to drill out the rivets) to remove the fender flare, then it’s just screws to take out the fender liner.

[jbash87]

Originally Posted by RL18

It’s actually a pretty simple job. Remove tire on passenger side. Then you need some fender flare rivets, a rivet tool, drill and a drill bit (to drill out the rivets) to remove the fender flare, then it’s just screw to take out the fender liner.

It is simple as RL18 has stated. I wanted to clarify for anyone reading this that you do not need to use a drill for the plastic rivets. I punch out the centers with a small screw driver then using a plastic pry tool pop the flanged parts.
The rivet tool is available for cheap at harbor freight. It comes with enough rivets to do the job once or twice.

[Best4x4xFar]

I will try the water test when I get a chance, but when I pulled he cow back out, it looked to have been reinstalled correctly. RL, your signature says 335d, is it a 335d or X535d you are referring to with the fender drain issue?

[RL18]

Originally Posted by Best4x4xFar

I will try the water test when I get a chance, but when I pulled he cow back out, it looked to have been reinstalled correctly. RL, your signature says 335d, is it a 335d or X535d you are referring to with the fender drain issue?

I have both but I’m talking about my x5d

[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?

[jbash87]

Originally Posted by Best4x4xFar

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?

Yeah just disconnect the battery and replace them.

That flat box is a grounding block. "Fan Connector" is the style of the block itself. It has nothing to do with any fans in the vehicle.