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Discussion Starter · #1 ·
Finally getting back to my oxfordgrun e34 msport after buying a fixer upper house during the pandemic and getting sucked into that black hole.

Anyway thats in decent shape now so first order of biz is fixing the EDC struts which seem to be locked in extra hard mode. They are not leaking and I changed the accumulators so main guess at this point is electrical gremlins. I’ve been scouring every BMW EDC post i can find on the internet and finally felt i learned enough to take some some voltage readings at the pins today. What I found was pretty weird.

Attached are voltage measurements at the 10 pin connectors.

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The 10 pin seems to have two states. The first one where every signal pin is fluctuating between 6.6 and 8.8V. This one is just weird and I dont know what to make of it. There is no EDC error during this time.

Then state 2, if I unplug and replug the 26 pin connector with power on, the dash will throw an EDC not active error, BUT(!) the voltage oscillation stops and most of the control signalsare either in a reasonable place except that they show 8.7V insted of the expected 4.5.

The 26 pin connector mostly looks ok except I have a few 5v signals where they shouldnt be but honestly that seems pretty secondary to whats going on with the 10 pin at this point.

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Discussion Starter · #2 ·
Next step I think will be to check the solenoids at each corner and try to get them to engage independently to make sure they are still functioning.

Also, I have another EDC IV brain box in the mail. It comes off of a 96 750il I believe, but is the exact same part number as the one in the E34 M-Sport. Hopefully this will allow me to switch back and forth and debug.

E38 box:

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My box:

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Discussion Starter · #3 ·
Looks like bad news today. Brought home a power supply to test out the solenoids themselves. Tried front right first. Both solenoids showed a resistance and when I applied 1A at 4.5V as specced, I could hear both solenoids clicking. Yes!

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I moved on to the left front aaaand…. not as much luck :(. I’m seeing 0 ohms resistance on both solenoids and when I pass a voltage through, I dont hear anything. I had a brief moment of hope when I noticed the EDC wire had been repaired previously and was hoping the repair might just be failing. But when I pulled it apart I got the exact same readings.

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Both front shocks were replaced with new units about 50k ago and have no leaks, so I’m surprised to see both of the solenoids on one side totally gone and the ither side seemingly fine.

Is there anything I might be missing? In the absence of that, is there anyone that’s done repairs on just the solenoid valves themselves. Seems like the rest of the shock is fine, but if the solenoid is gone and there’s no way to repair, they might have a trip to Poland in their future…..
 

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Discussion Starter · #4 ·
Well, just checked the rears as well. Both seem working fine: uniform resistance and that sweet clickity clack when voltage applied. Going to look deeper into the front left later this week but I’m not holding out a ton of hope.

To help someone down the line, here are the measurements I took off of the EDC plug.
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One thing I thought I might try was to keep the rears EDC/SLS while swapping the fronts when they are in Poland. Only thing I imagine the system could be checking is resistance right?
 

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FYI,
I did some testing of the EDC solenoides when I had my EDC dampers dyno tested.

With Respect to the 4.5V EDC solenoid specification.
I anticipation this is a "solenoid holding voltage" value and not the solenoid energized voltage.
Solenoides require much more voltage and current to energize than to hold once engaged.
I would suggest using 8 volts to test engagement "solenoid energized" and then reduce the voltage to 4.5 once energized.

Also, I had one of my front EDC shocks repaired with a bad Ohm reading and it was the harness not the EDC internal wiring or solenoid.
It would seem the harness wire often breaks at the grommet where the harness attaches to the shock.

All the Best
 

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...not as much luck :(. I’m seeing 0 ohms resistance on both solenoids and when I pass a voltage through, I dont hear anything. I had a brief moment of hope when I noticed the EDC wire had been repaired previously and was hoping the repair might just be failing. But when I pulled it apart I got the exact same readings.
…..
0 ohms reading would seem unusual for the readings around the plug.
Not much difference between 3 ohms and zero ohms
Zero ohms would indicate all 3 wires (A-B-C) or both solenoids are shorted together.
Infinite resistance is more typical for a single solenoid or the common solenoid wire (C) could open and cause an open circuit for both solenoids.
 

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Discussion Starter · #7 ·
Also, I had one of my front EDC shocks repaired with a bad Ohm reading and it was the harness not the EDC internal wiring or solenoid.
It would seem the harness wire often breaks at the grommet where the harness attaches to the shock.

All the Best
Verrrry interesting, that’s also the place where it splits off of one 3 wire line to each individual solenoid. I’ll def take a closer look this weekend.

I would suggest using 8 volts to test engagement "solenoid energized" and then reduce the voltage to 4.5 once energized.
I was able to hear solenoid activity on the other 3 shocks when applying 4.5V, but I will keep 8V in mind as an additional test case or for further debugging.

0 ohms reading would seem unusual for the readings around the plug.
Not much difference between 3 ohms and zero ohms
Zero ohms would indicate all 3 wires (A-B-C) or both solenoids are shorted together.
Infinite resistance is more typical for a single solenoid or the common solenoid wire (C) could open and cause an open circuit for both solenoids.
I agree it seems unusual, especially to see the same behavior for both independent solenoids, but I’m not very experienced with failure cases for valve solenoids. A quick google search had convinced me that 0 ohms could indicate a short through the valve solenoid itself but I have no idea if that’s a common failure case or even possible to be honest. It would be great if it was in fact just the harness.

Thanks so much for responding by the way, this type of feedback is invaluable! Will report back what I find out.
 

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Discussion Starter · #8 ·
Wow @m6bigdog you are a genius! Cut the harness after the split and can confirm I’m reading 3 ohm at each solenoid + can hear them activating when applying voltage !!

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Still not there yet but feeling much better than yesterday! Now time to figure out how to repair this harness..
 

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...Cut the harness after the split and can confirm I’m reading 3 ohm at each solenoid + can hear them activating when applying voltage !!
...
Still not there yet but feeling much better than yesterday! Now time to figure out how to repair this harness..
Unfortunate for both of us; but there was a day when I could have got my hands on a significant supply of the front EDC harnessed. Little did I now, those days are long gone.
That I'm aware even Nagengast cannot replace the EDC harness when they rebuild shocks.
So that leaves finding early model EDC shocks from an E32 that can be salvaged as a repair harness!!
Also, 3 conductor, high flex cord should be easy to purchase. The bummer is the male connector is not available.
I will investigate and post my findings.
Having fun now!!!
 

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I have yet to investigate the EDC flex cable.
You will want to use the cable specifications and physical drawings as a comparison.
Wire gauge is not as important as overall cable diameter.
However, below is my best guess of a Continuous Flexing Control Cable that may work.

I would measure the EDC cable diameter and select a 3-conductor unshielded cable that is a close fit.
To make a new cable the splices must be weather proof and completed in areas that will not be subject to flexing.
The cable splices must be expertly completed with bonding tape/liquid tape at each wire splice and then a sealed cable jacket repair so it will last in the harsh vehicle suspension environment.
I would also want to use as much of the original harness mounting/strain-relief grommet components as possible.

Continuous Flexing Control Cable:
3-M Electrical Tape:
 

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Discussion Starter · #11 · (Edited)
Good info. For the time being I’m going ahead with a temporary solution so that I can verify that the rest of the system is working as expected. For this I used shielded flex cable with soldered connections and shrink wrap. Some connections were tough to solder to I bought some heat shrink solder seal connectors to use on the final version. I think the most sensitive part is still the part where it branches off from 1x 3 wire flex to 2x 2 wire flex. For this part I’m planning to either use a weatherproof sealed connector or to do some soldering and encase it in a gel splice enclosure.

One thing to be careful of when attempting this type of repair is to keep straight which wire goes to which solenoid, you want to make sure you don’t accidentally swap them. This is made additionally frustrating because the inner wires to both solenoids are the same color (brown and black).

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The only way to tell them apart is from the outside wiring. In my unit, the upper solenoid wires (on both sides) had a red piece of tape around them. The shared wire is the black wire, the upper solenoid takes the brown wire from the 3 wire and the lower solenoid takes the blue wire (I believe, it was pretty late).

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Discussion Starter · #12 ·
Anyway after fabbing and installing the temporary front left EDC harness, I was able to verify resistance and activation of the both solenoids in that shock at the factory 3 pin connector in the wheel well.

I was hoping this might allow the entire system to spring back to life, so I disconnected from battery for 30min and took it out on the road. Again, no luck, the shocks were stuck in firm mode.

At this point I’m thinking my next steps will be to 1) verify I can activate all the solenoids from the terminating loom by the EDC box 2) if that works, it’s probably time to invest in a DIS / INPA rig so I can debug the computer itself.

Would also be nice if I could test it with a known working EDC box / switch but both are now NLA and I don’t know anyone in the area with working Nurburgring package.

Thoughts?
 

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Discussion Starter · #13 ·
Update: I was able to activate all the solenoids from inside the vehicle. Hear clicking when voltage on and voltage off. To give them a test I hardwired the shocks into Comfort mode (5v 2A to pins 8&9 and ground to pins 1&3 of the 10-pin plug) and took it for a ride. The front was nice and compliant but the rear was still super stiff and clunky.

At this point I think something must be up either with SLS or the rear shocks themselves. I replaced accumulators recently so they have fresh nitrogen packs. I also flushed all the old chf 11s with fresh new stuff and adjusted ride height. The rear does go up and down when I adjust the valve (although up is significantly slower than down).

Not sure what the next move is…. Has anyone had a stiff and clunky rear even after replacing accumulators, fluid and adjusting ride height?
 

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interesting thread with alot of good things to check.

Im starting the same project with my 540 that has edc 3 + SLS, edc nicht aktiv in the display and left rear shock is leaking bad....

This will be fun, gonna start with some ohm measuring and applying voltage to the solenoids :)
 
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