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Inchyra,
The EDC controller for the E34 is also used in the E31, E32, E38 & E39.
These controllers are uncoded and need to be coded for the specific vehicle when installed.

There is a couple of BMW documents on EDC's. One is an early version 1990 Service Bulletin and a more specific vehicle version that included later model vehicles in the ST56 (date: 01/03). These documents cover the system failure modes and failure default settings.

That I can tell, the shock solenoid performance is pretty much the same for all versions but the number of accelerometer (2 or 3) and the coding is the relative difference between vehicles and EDC versions.

Attached is the early BMW EDC III Service Bulletin (1990)
 

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Thanks for this. Yes I'm sure EDC is fundamentally the same but another forum has an extensive thread on the differences between EDC111 and EDC PLUS. When troubleshooting It's frustrating not to have an accurate schematic for my very early 3.8, I can only find info in ETM for earlier or later cars.
 

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Discussion Starter #43 (Edited)
Thanks for this. Yes I'm sure EDC is fundamentally the same but another forum has an extensive thread on the differences between EDC111 and EDC PLUS. When troubleshooting It's frustrating not to have an accurate schematic for my very early 3.8, I can only find info in ETM for earlier or later cars.

Can you link the other thread?

Also both my 93 (5/93 build) and 94 (10/93 build) edc computer say edc plus on them.
 

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Inchyra,
I think you have found a difference without distinction.
Below is the supersession information on the EDC controllers
As you can see EDC p/n: 37 15 1 139 600 was superseded in Nov. 23, 1995.
I believe the current EDC module is identified as EDC4 and fully compatible with EDCIII & EDCIII+ etc. and the current E34M5 EDC coding.

Since BMW is not very good at documenting a unique and limited production system, especially when it is a single year and end of production utilization. Therefore, all we can do is rely on their documentation of the system in related vehicles that use the exact same system components like the E31, E32 & E38. The EDC is not the only system that is this way as in many vehicle repair manual or construction group documents BMW will refer to another vehicle series for the details of the system.

While the EDC control modules are the same they perform the essential function to interface the accelerometers and provide a power driver for the shock solenoids, it is the module coding that determines how the input from the 3 accelerometers is conditioned and therefore how/when the front and rear shock solenoids are switch between soft - medium - hard settings.

The P mode (Program) is the essentially same as Komfort (Komfort sounds silly for an M5) and uses all three (soft-medium-hard) settings and the S mode (Sport) restricts the shock to the 2 firmest (medium-hard) settings.

<TABLE cellSpacing=1 cellPadding=1 width="100%" border=0> <TBODY> <TR> <TD class=table style="FONT-WEIGHT: bold" align=center>0</TD> <TD class=table align=center></TD> <TD class=table style="FONT-WEIGHT: bold" align=center>37 15 1 092 572</TD> <TD class=table style="FONT-WEIGHT: bold" align=left>Control unit EDC uncoded</TD> <TD class=table style="FONT-WEIGHT: bold" align=left></TD></TR><!-- Datenzeile (Info-I, Teilenummer, Benennung, Entfall-Datum) --> <TR> <TD class=table align=center>1</TD> <TD class=table align=center></TD> <TD class=table align=center>37 15 1 162 631</TD> <TD class=table align=left>Control unit EDC uncoded</TD> <TD class=table align=left>23.11.1995</TD></TR><!-- Datenzeile (Info-I, Teilenummer, Benennung, Entfall-Datum) --> <TR> <TD class=table align=center>2</TD> <TD class=table align=center></TD> <TD class=table align=center>37 15 1 139 600</TD> <TD class=table align=left>Control unit EDC uncoded</TD> <TD class=table align=left>23.11.1995</TD></TR></TBODY></TABLE>
 

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I have no knowledge of EDC4 but if you are saying that an EDC4 Controller can be re-programmed (coded) to work with an earlier EDC system then that is certainly useful to know when sourcing parts. I do disagree however that the differences between the various EDC systems and particularly any differences between model years in the same EDC system are "without distinction" - insignificant??

When trouble-shooting EDC, as I am at present, I believe it does matter where the speed signal is coming from for instance, and how many sensors there are and their location, and certainly whether EDC111 / EDC Plus shocks are different in design even if the function is the same.

I remain frustrated that BMW have not produced an accurate schematic for every variant (or if they have I haven't been able to find one for MY92). I spent an uncomfortable couple of weeks in the South of France because Jaguar had decided to fit an additional in-line fuse to protect the A/C but not bothered to update the wiring schematic in the car handbook. This was almost expected of Jaguar - it provided what people of my age called 'character' to excuse failings in English cars but frankly I expect better of BMW.
 

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I have no knowledge of EDC4 but if you are saying that an EDC4 Controller can be re-programmed (coded) to work with an earlier EDC system then that is certainly useful to know when sourcing parts. I do disagree however that the differences between the various EDC systems and particularly any differences between model years in the same EDC system are "without distinction" - insignificant??

When trouble-shooting EDC, as I am at present, I believe it does matter where the speed signal is coming from for instance, and how many sensors there are and their location, and certainly whether EDC111 / EDC Plus shocks are different in design even if the function is the same.

I remain frustrated that BMW have not produced an accurate schematic for every variant (or if they have I haven't been able to find one for MY92). I spent an uncomfortable couple of weeks in the South of France because Jaguar had decided to fit an additional in-line fuse to protect the A/C but not bothered to update the wiring schematic in the car handbook. This was almost expected of Jaguar - it provided what people of my age called 'character' to excuse failings in English cars but frankly I expect better of BMW.

I believe you are overlooking the similarities of the EDC system between the various BMW series vehicles.
As long at you are referencing the vehicle systems that use the same controller the system troubleshooting and component performance will be nearly identical from the functional perspective.

The E31, E32 & E34 all use an EDC shock with an external Soft & Medium rate solenoid and use the same uncoded controller. The biggest difference is the variation between 2 or 3 accelerometers but the ETM EDC diagrams are identical for the 2 or 3 accelerometer versions.
The EDC shocks from an E32 are a direct fit for the E34 chassis but the valving would be wrong.
Yep all three cars have their own coding for the EDC controller to accommodate the difference in suspension dynamics.

Hence, when the new uncoded EDC controller is installed it must be coded for the specific vehicle or the EDC system would not function!! If a used EDC controller is salvaged from a different model or vehicle series it will need to be recoded or the EDC controller will continue to function with the parameters of the original vehicle.


just incase you want it in German here is a diagram from a Euro ETM
Also added the 1995 M5 Sales Brochure:
 

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Because I really hate it when others don't complete threads - leaving the audience wondering what the outcome was - I'll post the culmination of my search to discover why my rear EDC shocks were (apparently!) "stuck on firm".

Earlier this year I had what I thought was fully working EDC front and back. Then a leaking rear shock was reported during a service so I sent both rear shocks to Nagengast. When they returned, the invoice had a line on it recommending replacement of the accumulators when re-fitting the shocks. I ignored this as they seemed to be working perfectly before the shocks were removed. The ride with the refurbed shocks seemed harsh in the rear so back to the (independent but ex-BMW) garage, who put their Autologic scanner on and reported that the scanner couldn't switch the rear shocks out of the firm setting although they could switch the fronts. This suggested an electrical / control fault so I had them check all the usual suspect places such as over the subframe, and replaced the EDC controller and the relay. Nothing changed so I took the car to the local main dealer who also checked all the wiring continuity and diagnosed faulty shocks. Told them they had been rebuilt - so could it be anything else? No, must be shocks. So email to Nagengast - who were extremely helpful and sent me a test procedure to check if the solenoids in the shocks were working. Which they were, so Nagengast asked if I'd replaced the accumulators as they were "90% sure that was the problem". Back to main dealer to ask whether the accumulators could be at fault? Yes came the reply. So why didn't you tell me this before? "Because we dont have the equipment necessary to test them"!!

Anyway, replaced the accumulators and all is now well. Unless anyone can think of a way that the accumulators can be damaged by replacing the shocks, I can only imagine that faulty accumulators were being disguised by weak shocks so everything evened out.

Moral of the story - take note of recommendations from people who know, dont take your car to the main dealers as they no longer have the equipment or interest in working on them - and are prepared to take c£3,000 off you to fix a £300 problem rather than admit the fact. Oh yes, and I'm now told that it's not possible to switch front and rear shocks independently even though the Autologic scanner suggested that it was.

:mad:
 

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Thanks Chris. This is really helpful - I had been wondering about the accumulators on mine, and I'm now leaning toward a Nagengast rebuild and accumulator replacement - I assume there are labour economies of scale as both jobs must involve replacing the fluid ?
 

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Chris, I had the same. A leaking rear edc shock and a very hard ride. New accumulators solved the problem. As far as I can tell, the one leaking shock doesn't leak anymore.

Apparently when the accumulators go bad, the oil pressure in the shocks becomes so high, they start leaking. It's probably not good for them, so preemtive maintenace here is not a bad idea.

Thanks for finishing the post with the solution!
 

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Because I really hate it when others don't complete threads - leaving the audience wondering what the outcome was - I'll post the culmination of my search to discover why my rear EDC shocks were (apparently!) "stuck on firm".

Earlier this year I had what I thought was fully working EDC front and back. Then a leaking rear shock was reported during a service so I sent both rear shocks to Nagengast. When they returned, the invoice had a line on it recommending replacement of the accumulators when re-fitting the shocks. I ignored this as they seemed to be working perfectly before the shocks were removed. The ride with the refurbed shocks seemed harsh in the rear so back to the (independent but ex-BMW) garage, who put their Autologic scanner on and reported that the scanner couldn't switch the rear shocks out of the firm setting although they could switch the fronts. This suggested an electrical / control fault so I had them check all the usual suspect places such as over the subframe, and replaced the EDC controller and the relay. Nothing changed so I took the car to the local main dealer who also checked all the wiring continuity and diagnosed faulty shocks. Told them they had been rebuilt - so could it be anything else? No, must be shocks. So email to Nagengast - who were extremely helpful and sent me a test procedure to check if the solenoids in the shocks were working. Which they were, so Nagengast asked if I'd replaced the accumulators as they were "90% sure that was the problem". Back to main dealer to ask whether the accumulators could be at fault? Yes came the reply. So why didn't you tell me this before? "Because we dont have the equipment necessary to test them"!!

Anyway, replaced the accumulators and all is now well. Unless anyone can think of a way that the accumulators can be damaged by replacing the shocks, I can only imagine that faulty accumulators were being disguised by weak shocks so everything evened out.

Moral of the story - take note of recommendations from people who know, dont take your car to the main dealers as they no longer have the equipment or interest in working on them - and are prepared to take c£3,000 off you to fix a £300 problem rather than admit the fact. Oh yes, and I'm now told that it's not possible to switch front and rear shocks independently even though the Autologic scanner suggested that it was.

:mad:
FYI,
A bad accumulator will cause the SLS shock on that side to leak and can damage the SLS shock rod seals if the bad accumulator is not changed out promptly!!<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com<img src=" /><o:p></o:p>
<o:p></o:p>
Testing the SLS system:<o:p></o:p>
The SLS/PS Fluid reservoir level is checked by raising the rear wheels and letting the accumulators discharge to minimum pressure. I have found this less than informative for detecting a failed accumulator because the SLS system remains charged. However if an accumulator fails the normal reservoir fluid level should be lower than the normal level since one or both accumulators won’t discharge any of the fluid and some of the fluid will fill the gas void in the accumulator.<o:p></o:p>
<o:p></o:p>
Any DIY'er or shop tech can test the SLS accumulators and you can discriminate whether it is just one or both accumulators that have failed.<o:p></o:p>
The procedure is one I have suggested for many years.<o:p></o:p>

The car needs to be on its wheels and either rear wheel can be removed by lifting just that corner.<o:p></o:p>
Once the wheel is removed place a drain pan under the accumulator area to catch all the discharged fluid.<o:p></o:p>
Then with a small shop rag 12x12 over the flare-nut wrench at the flare nut to prevent the fluid from spraying all over the place and with caution you will ever so slightly loosened the flair nut at the accumulator.</SPAN>

Again, this procedure needs to be done with caution and the shop rag needs to be in place before the flare nut is loosened, because the hydraulic fluid is under high pressure and covering the flare-nut wrench and flare nut keeps the fluid from spraying all over so you can measure the drained fluid.
You can also put a hose on the system bleed screw on the SLS control valve and drain the system from here. I find the SLS bleed screw harder to access.

You will wait several minutes while the fluid drains under pressure and once the steady stream of draining fluid starts dripping the accumulators are discharged.
When the both accumulators are good there should be around a quart of fluid discharged.
If only one is good there will be around 1/2 quart.<o:p></o:p>
If both are bad the amount of fluid drained under pressure will be only an ounce or two.<o:p></o:p>
<o:p></o:p>

Also note, a bad accumulator will most likely cause the SLS shock on that side to leak/weep.<o:p></o:p>
Because, when the shock rod is pushed into the SLS shock some of the fluid will be discharged into the accumulator and if the accumulator has failed the internal pressure in the shock will spike since the accumulator bladder has failed and the fluid will need to travel through the small connecting piping to the good accumulator. The firm bouncy ride is due to the fact the fluid in the shocks have no functional accumulators to discharge the fluid into. A single bad accumulator is difficult to assess from the driver seat however it cam cause the shock rod seal to fail from the pressure spiking on the bumps encountered. Hence I recommend replacing the accumulators as a PM every 5-7 years and testing the accumulators annual and/or if you suspect something is wrong in the rear suspension and replace the drained fluid with new.<o:p></o:p>
 

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Hi Matt. Not much economy of scale on the labour I'm afraid but yes I guess there is on the fluid. Changing the accumulators is a pia job. Hoses were corroded into mine so changed those as well. Note that febi bilstein sell accumulators. Drop exhaust to change n/s (RHD) one. Based on Theo and M6bigdog posts and my experience, it might make sense to change the accumulators before refurbing shocks. Any Leaks may stop and ride improve. BTW, accumulators can be pressure-tested if you can find someone with the right equipment or see M6bigdog post and Nagengast offered to rebuild / repair mine if necessary so you could just send them everything at once for 100% solution?
 

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Guys - this is becoming a great thread.

Bigdog - if there was a way to thank you twice for that post then I would - this is splendid stuff.
 

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Hi Matt. Not much economy of scale on the labour I'm afraid but yes I guess there is on the fluid. Changing the accumulators is a pia job. Hoses were corroded into mine so changed those as well. Note that febi bilstein sell accumulators. Drop exhaust to change n/s (RHD) one. Based on Theo and M6bigdog posts and my experience, it might make sense to change the accumulators before refurbing shocks. Any Leaks may stop and ride improve. BTW, accumulators can be pressure-tested if you can find someone with the right equipment or see M6bigdog post and Nagengast offered to rebuild / repair mine if necessary so you could just send them everything at once for 100% solution?
One more thing,
I have the gauge set!
However, since the accumulator are essentially piped in parallel, one at each shock, the gauge pressure drop procedure requires disconnecting each side, shock & accumulator, at the "Tee" block and you'll need to discharge the fluid/system pressure three times to hook up the gauge set and run the test procedure for both accumulators.

Also, reading the gas pressure in the accumulator is just about useless, unless you just happen to have an accumulator that was manufactured out of spec. because the accumulator will loose the gas pressure by leaking the hydraulic fluid behind the accumulator bladder and when that leak occurs the accumulate is dead in short order, therefore it will not discharger fluid under pressure.

So, IMHO, for diagnosing the accumulators - forget the gauge and just bleed the pressure off and measure the amount of discharged fluid, record the amount and replace the drained fluid as a PM procedure. Also, you will want to perform the drain procedure in the same manor each time, i.e., car on the ground with 1 rear wheel off the ground (or both rear wheels dropped depending on your lift equipment) because as the system pressure changes (lifting the wheel(s) extending the shock(s) after the engine is shut off) the fluid stored in the accumulator changes making the fluid drained under pressure somewhat of a variable, however a single bad accumulator would be pretty obvious regardless.
Also, if your shock rod seal aren't leaking (some weeping is normal) having to pay the labor hours for a shop to perform the gauge procedure is expensive and I bet you would be money ahead just to replace the accumulators as a PM if they have been in service for 5-7 years and just R&R them every 4-5 years unless you sense something is wrong in the SLS.

I guess I'm conflicted about accumulator testing as there is little obvious outward indication of a single bad accumulator other than a possible leaking shock rod seal yet waiting years for the second accumulator to fail with the obvious bouncy ride is not good on the shock seal, shock tower sheet metal and/or upper strut mount/isolator with the bad accumulator. Hence, I'm not saying having your SLS tested with gauge set is useless as there are some problems where the gauges are very useful but for accumulator testing I think the gauge test is excessively complex and costly for either the tool or shop labor hours.

Just another one of those "pay for it now or pay a lot more later" maintenance issues.
 

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edc

My car has very firm suspension, the dash switch is not illuminated at all. I realise i need to get a specialist to look over it but wondered whether the switch not being lit gives a clue to the problem?
Thanks
Ian
 

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My car has very firm suspension, the dash switch is not illuminated at all. I realise i need to get a specialist to look over it but wondered whether the switch not being lit gives a clue to the problem?
Thanks
Ian
Does yr switch light up in either setting ?

It could be a problem with the switch , but a decent diagnostic test will confirm .

D
 

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Nope, switch has no illumination. Anyway of bypassing it?

Ian
Just because the switch doesn't illuminate doesn't mean to say it doesn't connect to the shocks , it may be that the lamp has simply burnt out .

Have you ever seen them light up ?
 

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Discussion Starter #60
do you get an 'edc not active' warning in the display?

When you start your car does the edc switch light up for just a second before going dark?

Are you sure you have all of the edc components? (computer under rear seat, etc). Has the system ever worked since you've had the car?

As david says you need to have the faults checked. Could be simple like a bad accelerometer, or broken wire in the rear harness.
 
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