[JoshS98]

Originally Posted by gbalthrop

See attached ISTA ScreenPrints of DSC wiring SSP, Lines ID, Connector Location & Connector View, along with
Location of X170 DSC Ground Location. You have multiple Faults indicating the DSC is NOT communicating. You also have
an INPA Identification Screen showing NO "29 DSC" appearing after "18 EGS". When a module is NOT communicating, that
suggests:
1) No power supply to Module, OR No Ground;
2) No Bus communication with JBE Hub;
3) Faulty Module.

So Test for Voltage supply, fuses F20, F35 & F65; Ground at X170; Inspect pertinent Pins & Connector Sockets for
Voltage Supply, Ground & Bus (PT- & F-CAN). That means X18303/1, 17, 32, 16, 42, 11, 15, 26 & 30.

Your Fuse Charts do NOT agree with the attached ISTA Fuse Charts, showing fuse Location: F20, F35, F65.

Also see ISTA "Tutorial" pdf: ISTA as Shop Manual, for how to view wiring diagrams, repair procedures & other documents.
Please let me know if specific test methods, using Multimeter, are desired.
George

Just went and checked all those fuses with a multimeter and all fuses do show voltage across. That is F20, F35 and F65, with all of them showing 12v across with ignition on.

Both X170 pins on the DSC connector have continuity to chassis ground.

Using those X170 pins as a ground to test

1 shows 12v
17 shows 12v
32 shows 12v
16 x170 ground like pin 47
42 shows nothing
11 shows 3.1v
15 shows 2.5v
26 shows 1.9v
30 shows 2.3v

Edit: Recounted everything twice just to make sure I was testing the correct pin and pin 42 definitely has no voltage

[JoshS98]

So reading this wiring diagram

32, 17, 1 are coming from the fuses and all show 12v

16, 47 are ground and show that

42 shows no voltage, but seems to be the negative connection for the Right Rear wheel speed sensor. Pin 43 would be the positive for that. Checking pin 43 shows me 0.01v occasionally.

If my understanding of how the wheel speed sensors work they should be showing 0v if I am not moving.

30 and 15 are PT-Can High and Low respectively, both show voltage

26 and 11 seem to be F-Can High and low respectively, both also show voltage

Looking more at the wiring diagram, I see pins 34, 45, 43, 36. One for each of the wheel speed sensors.

Checking all of those give me no voltage besides that the very random 0.01v I could read on pin 43 for the right rear wheel.

So sorry if I’m reading this diagram wrong, just wanted to check what I should be expecting on 42 and noticed it’s the ground wire. New to reading vehicle wiring diagrams so totally possibly you’re right here and I’m just missing or overlooking something

Typed my vin into ISTA+ and followed that guide to get this diagram so definitely should be correct.

Edit 2: I found an old forum post on a different site where someone was able to solve this by calibrating the SWA with easyDIS. They also could not communicate with the DSC using INPA or NcsExpert. After they calibrated the SWA with EasyDIS it was picked up. Wasn’t able to find easyDIS but found normal DIS so I’ve started the painful procedure of getting that working and installed.

[NZE90]

Wheel speed sensor voltages/readings have no effect on the DSC being able to communicate. It looks as though you have 2 dud DSC units, but i personally wouldn't be confident in confirming that without using an oscilloscope on the PT-CAN.

[NZE90]

I've only just noticed your LDM is not communicating either. Was this the same when the old DSC unit was installed?

[JoshS98]

Originally Posted by NZE90

I've only just noticed your LDM is not communicating either. Was this the same when the old DSC unit was installed?

I want to say it was also not communicating. But I’m not 100% sure.

Looking through photos I took the first day with the car, I found some of the “Test Plan” screen.

Looking at those I do see an “ABL power supply for LDM code”

The same “test plan” entry is also present right now.

With that I think its safe to assume the LDM wasn’t working with the old unit installed either.

Going to see if I can rent an oscilloscope locally, I’ve checked Facebook marketplace and all the ones seem to be $150+. Getting close to the price of a new DSC unit at that point.

Just wanted to also say thanks for all the help. This definitely is a head scratcher and I really appreciate it

[NZE90]

I would troubleshoot the LDM problem before going any further as the DSC works very closely with the LDM. On later models the LDM was built into the DSC unit. Do the same steps for troubleshooting the LDM. Power and earth supplies and PT-CAN voltage checks.

[NZE90]

Finding a compatible DSC unit just got harder for you too if you do need one, as the later ones won't work with the separate LDM that your car has.

Just as a test, unplug the LDM module, then clear all your fault codes and see what faults come back. Leave the DSC plugged in.

[JoshS98]

Originally Posted by NZE90

Finding a compatible DSC unit just got harder for you too if you do need one, as the later ones won't work with the separate LDM that your car has.

Just as a test, unplug the LDM module, then clear all your fault codes and see what faults come back. Leave the DSC plugged in.

Away from the car for around 30 more minutes so I’ll get that tested and posted shortly.

Did a bit of googling about the LDM and found someone mentioned a cruise control error light.

Thinking back, the 4 days I drove before installing the new DSC I never once encountered a cruise control error light. I scrolled through the lights a few times. It was always an ABS light, airbag light, a cold weather light (-40c on ext temp sensor), ELV but only when off and parking (reset that counter, dealing with later).

But I know 100% for sure I never once saw this light until I turned on the car to remove it from the ramps after doing the DSC job.I took a photo to google it and never got around to it and forgot till now

Im also getting a clock light now but I’m assuming I just need to set the time as it disappeared after I left the battery unplugged for a few hours in an attempt to get this DSC working

Now with this new DSC whenever I start the car I get a cruise control error light.

Maybe this new DSC has an LDM built in and it’s causing some issues? Hopefully hasn’t fried anything if so.

I attached a photo of this light

[JoshS98]

Here is what everything looks like with the LDM unplugged

[NZE90]

Originally Posted by JoshS98

Maybe this new DSC has an LDM built in and it’s causing some issues?

Yes, this is very possible. The only DSC units that are compatible with your car are 2005 and very early 2006 E9x. I can't remember the exact date they changed but I've seen the information in Ista somewhere.

Have you checked the LDM for power, earth and PT-CAN?

[JoshS98]

Originally Posted by NZE90

Yes, this is very possible. The only DSC units that are compatible with your car are 2005 and very early 2006 E9x. I can't remember the exact date they changed but I've seen the information in Ista somewhere.

Have you checked the LDM for power, earth and PT-CAN?

Just checked those all pins seem to have the proper voltage. 5 and 6 are the PT-Can H and L lines. 16 seems to be general power, 17 is ground and 18 is the wakeup pin.

5=3.1v
6=2v
16=12v
17=ground
18=11v

So the LDM should be getting everything it needs, maybe I need a new LDM and new DSC.

[JoshS98]

Originally Posted by NZE90

Yes, this is very possible. The only DSC units that are compatible with your car are 2005 and very early 2006 E9x. I can't remember the exact date they changed but I've seen the information in Ista somewhere.

Have you checked the LDM for power, earth and PT-CAN?

I am so sorry, was doing this at 4am last night and I did forgot to reset fault codes after unplugging the LDM.

Doing so gives one additional error code about a Transmission control unit not sending a message.

I’ve attached the faults below. Disconnected LDM, cleared faults, read faults for the pics saying “No LDM”. Reconnected the LDM, cleared faults, then read faults for the pics with “LDM” written.

This is the first time I’ve dug into a car more than an oil change. So might be completely wrong here but since both the DSC and LDM aren’t connected than is this an issue with whatever “bus” they’re connecting too?

No idea how I’d diagnose that but both an LDM being dead and a DSC. It seems odd both would be dead to the point of not communicating at all.

I’m willing to admit the replacement DSC could be the completely wrong one or never tested before sale. I didn’t buy it or get an invoice. The gentleman who sold me the car told me about the DSC not working and just said he had a replacement in the trunk from eBay.

If needed I can always get the original DSC plugged back into the electrical connector to see if possibly the LDM will show up. But with the photo of test plan from day 1 ownership showing LDM power error I doubt it would change.

I really don’t mind trying absolutely anything at this point.

I found a local BMW scrapyard and they are looking for a compatible DSC for me and will call me back Monday. Can always also ask them for an LDM. Seem like good people, family run little thing.

[JoshS98]

Had some time tonight so I popped the old DSC unit back in. Didn’t attach the brake lines just plugged it in from the connector.

No change in the LDM or anything new in the fault codes. Cleared them and reread after putting the old DSC in. Posting the images of codes below.

I did try to listen to the DSC and heard some clicks it seemed like. But still doesn’t even show up.


Also had some time tonight peek into the white box full of wires. Was super careful taking it off and putting it back on. Everything inside looks clean and absolutely no signs of any sort of water damage. I didn’t unplug anything but everything was pristine. Uploading a photo of that too.

Maybe something I did somehow took out the LDM? Like I said before I never once saw a cruise control error pop up until I tried this new DSC unit. Now it’s here even after trying the old unit and clearing codes.

Edit: I forgot I have a UIF screen from day 1 ownership, in my 1st post on this thread. The LDM doesn’t show up there. So it’s definitely has always been offline

[JoshS98]

Want to also add the battery is a brand new, coded/registered Costco h7 80amp AGM.

There’s no corrosion on any terminals and everything in the battery compartment is clean. No signs of water damage.

There is a three wired connector coming off the negative terminal. The red is solid with no breaks but the two others are broken and reconnected with crimped connectors. Seems to be the battery IBS with the wiring diagrams I’ve read. Can’t imagine it would knock DSC and LDM offline either. The colours on the wire do match so I can confirm they are connected properly.

The DSC connector is also fully clean, I’ve inspected it and for good measure cleaned it with plastic safe contact cleaner.

All connectors test fine with a multimeter and visually look amazing. No signs of any corrosion or water damage.

Cars might not be my specialty but Ive been doing console repair for a few years so I’d like to think I’m pretty decent with electronics.

[NZE90]

Short of scoping and analyzing the pt-can signals there's not much more you can do. Maybe try and get a new LDM first as they are cheap and see if you can communicate with it.

[JoshS98]

Originally Posted by NZE90

Short of scoping and analyzing the pt-can signals there's not much more you can do. Maybe try and get a new LDM first as they are cheap and see if you can communicate with it.

Might see if I can borrow a scope. Get some more insight while waiting for the LDM to ship.

Just out of curiosity wouldn’t bad pt-can signals also take down other modules on that bus? I don’t see how a dirty signal or something would be isolated to just two modules.

Especially if the car genuinely runs and drives amazingly besides no DSC and cruise control. Drove it 3 hours home after buying it and was honestly a great drive with no issues.

Maybe just hopeful thinking

[JoshS98]

Think we’re getting somewhere here potentially.

I did an OHM reading between PT-Can H and L.

I did so by unplugging the LDM and reading pins 5&6 on that connector.

Ohm reading is 124ohms.

From my knowledge the DSC and the EKP both have a 120ohm resistor and these together should have 60ohms on the PT-Can line.

So I think it’s safe to assume one of those resistors aren’t working.

I had my old DSC module in the garage and read the ohms between the two PT-can pins on that. Showed as around 120.

So since I installed that DSC unit back in yesterday to see if it would make a difference and nothing happened. I think I can safely assume it’s not the DSC resistor but instead the resistor in the EKP?

Or could this be some other issue. I’ve read some other posts and it does seem like if there was a bigger issue I’d be getting a reading way different than just 124ohms which seems to point to just one resistor not being connected.

Most likely the EKP for previous reasons mentioned. But a bad fuel pump makes no sense considering the car runs and drives beautifully

Would love some more thoughts on this or how to go about diagnosing what is causing the ohms to be 124

Edit: Looked through the wiring diagrams on ISTA and found PT-Can ends at X14271. Taking an ohm reading from that connector with everything connected to the PT-Can also gives me a 124ohm reading.

Unplugging the DSC and taking an ohm reading from that connector gives me no results, the multimeter acts like I have the two probes separated. Does this point towards a issue with the wiring between the DSC and the rest of the car?

[NZE90]

Originally Posted by JoshS98

Unplugging the DSC and taking an ohm reading from that connector gives me no results, the multimeter acts like I have the two probes separated. Does this point towards a issue with the wiring between the DSC and the rest of the car?

You maybe onto something. Definitely sounds plausible. If you do a continuity check between the PT-CAN wires at x6021 and the DSC what results do you get?

[NZE90]

There is a PT-CAN junction in the LF wheel arch area that runs to the DSC. It could be susceptible to water damage. It is not a plug though, it's a crimp join which is wrapped into the harness. I have seen these corrode before and cause CAN problems.

[Bims328i]

You can get those things for pretty cheap (2-channel) these days provided you don't need a super advanced scope.

[JoshS98]

Originally Posted by NZE90

There is a PT-CAN junction in the LF wheel arch area that runs to the DSC. It could be susceptible to water damage. It is not a plug though, it's a crimp join which is wrapped into the harness. I have seen these corrode before and cause CAN problems.

Will get the wheel off and check that, do you know where about the crimp joint is? Or what the number is for it? Trying to narrow down the search area

Opened the box up to get access to X6021 and my connector seems to be different. Only 8 pins with 2 missing connections. ISTA shows it as 4 pins with 8 more pins above. I have a connector with 2 rows of 4. Attached some photos below. Forgot a photo of the opposite side but pins 1-4 are 1=Blue/Red, 2=Red, 3=Blue/Red, 4=Red

Wire colour and pin position does match, ignoring the wrong connector. Testing off of those for continuity with the DSC gives these results

Pin 30 on the DSC is PT-Can H so tested that to pins 3 and 1 on X6021. On pin 1 I have no continuity but on pin 3 I have continuity.

Pin 15 on DSC is PT-Can L was tested to continuity to pins 2 and 4 on X6021. On pin 2 I have no continuity but on pin 4 I have continuity.

[JoshS98]

I 100% need someone smarter than me to confirm but I think I have found the issue.

The EKPS should have a resistor inside between the PT-can lines.

I just pulled my EKPS, module itself says EKPM2 so confused there, perhaps the wrong one installed at some point?

Anyways here is the important info, All these tests were performed on the EKPS module itself.

I tested pin 9 (PT-Can high) to pins 15 and 16 (PT-Can low). Between those lines I have no readings, the multimeter acts like the probes are apart. I forget the proper term for this, hope my explanation makes sense.

I then tested pin 8 (PT-Can high) to pins 15 and 16. I have the exact same results. No resistance at all, the multimeter acts like the probes are apart.

There is no 120ohm resistor in my EKPS module. I also found some corrosion on the right mounting bolt for the module.

I will attach photos below of the corrosion and also the pinout guide I was using to take these readings.