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Fault Code 005506 SMG problem (still)

14K views 31 replies 9 participants last post by  platii 
#1 · (Edited)
Hi All,

I'm having no luck with my dealer so I'm trying to diagnose it myself.

I have INPA and EDIABAS ISTA+ now, both of which talk to my car (finally).

My car is continually popping up with a fault code 005506 - SMG FAULT with the red cog and won't shift once the cog is up.

From what I've learned or been able to diagnose so far, I may have an electrical fault, an accumulator issue or the SMG Solenoid might be at fault.

My other worry is whether or not it might be just an electrical gremlin caused by the SMG relay which apparently is a common issue with these cars.

One part of the diagnosis says I have an electrical fault, one part says clutch valve, break in wiring. One part says the accumulator pressure is defective. Previous diagnosis said clutch solenoid... It can't all be at fault.

I don't think it's the clutch as the car drives fine once the fault code is cleared, right up until it comes back...

The part that concerns me is the ever worsening Hydraulic pressure reading, which has now dropped from low 70s to high 50s in the last few tests run.

I really would like my dealer to help but they just want to replace major components until it stops happening and hope a part they replace is the culprit.

Help?
 

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#2 ·
Checking the relay(s) - I believe that there is one pink and one black - is fairly straightforward and a low cost way of starting to eliminate possibilities. I understand that all sorts of strange things happen when the wiring insulation deteriorates on one of the wiring harnesses on the SMG. There are many threads about this and how some have repaired the harness. There is no part number because it can't be replaced except with a whole "new" SMG.
 
#3 ·
So I re-ran all diagnosis again yesterday after re-teaching the clutch functions.

The issue still persists so I ran through the fault finding steps.

I checked all electrical connections with no noticeable drop in the mA during the test (+/- 200mA) to ~1000mA.

I then checked accumulator pressure static which came up with 28.0 bar preload pressure. The set values show 29-45 bar so this part has reported as faulty. Can accumulators fail as an individual part and if so, can they be replaced as an individual part or must the whole SMG control hydraulic unit be replaced, pump and all?

I went to test the control unit (SMG ECU) but the test didn't respond. I tried ceasing diagnostics twice and re-running the test but still no joy. The only other example I could fund on the forum of fault code 005506 reportedly solved the issue by replacing the SMG ECU so I'm curious to know if this might be the cause which is leading to the Accumulator failing the test due to receiving a faulty signal?

The run tests have show progressively worsening 'Hydraulic pressure - Actual Value' whenever I test (~52-54 Bar instead of ~75 Bar) but I don't know if this is due to the point when the fault code presents or whether the fault code presents because of this?

Sorry for the techno babble. I'd much rather update on my new carbon bits and planned exhaust mods but I'd rather be able to drive the car first in order to do that!

Thanks!
 
#4 ·
So, I've replaced the battery to better enable stable voltage during testing but no change.
Now I can't get the last report of the fault code to clear even when deleted in the fault history it pops straight back up.

Can the accumulator fail as a stand alone part and can it be replaced?
What's the likelyhood of this part failing and can I tell if it has failed if the actual clutch valve is faulty?

The accumulator passes the initial bleed down and static pressure test and holds above 40 bar (to ~57 bar) but never reaches nominal operating pressure of 75 bar.

Help?
 
#5 ·
Can the accumulator fail as a stand alone part and can it be replaced?
What's the likelyhood of this part failing and can I tell if it has failed if the actual clutch valve is faulty?
Answer is yes and yes.

If the clutch valve and/or the SMG unit valves are leaking (internal or o rings) the accumulated pressure will of course drop faster than usual, and could lead you think the accumulator is faulty or the pump is weak.

Lack of pressure or pressure holding might come from five reasons only:

Faulty pressure sensor.
Electric motor of the pump worn out (brushes, or coil)
Hydraulic pump worn out (internal leaks)
Accumulator bleed ( the pressure chamber is not anymore sealed)
SMG hydraulic system is bleading internaly or externaly ( Dry O-rings on solenoid valves, worn valves (internal exessive clearance))


You might also check that you have enough fluid in the system. This is apparently often the case that Indies are forgetting to prime the hydraulic pump when refilling the SMG hydraulic unit, and re-top the fluid level, this leads to lack of fluid. If there is not enough liquid the pressure can not build up. That is common sense.

Specialists on the forum might tell you how to sort out the real cause with diagnosis tools or tests. I am too new to this car to be of great assistance, at the moment.

Good luck.
 
#6 ·
Question....when you first unlock the car after it has been sitting long enough for the hyd. Pressure to fully drop off, does it sound like the pump is running for an extended amount of time? Just for a reference, Mine initially primes for about 10 seconds to make it to the 70 bar setting. As the car sits (while running) , it will normally bleed down to the 50 bar minimum after around 7 mins, then prime back up to 70 bar in about 3 sec. So far it is very consistent on the time it takes for these priming. The reason for the question is that, if yours is not taking the same amount of time each time it cycles (yours may normally cycle different than mine) initially or on re-prime, and the fault pops up as it is trying to prime and halts the pump, this might help to determine if it is loosing electrical signal or just not able to complete the priming in time.
 
#7 ·
Thanks for the reply,
Quick question, obviously I'm not fully up to speed on this car yet. I was really hoping I'd be able to use it before I had to start fixing it but such is life.
How can I check the accumulator pressure on start up with live feed? Can ISTA or INPA provide it as a read out if plugged in? If so, how can I view it?

To answer your questions, the pump only runs for max 10 seconds on prime, sounds strong and constant (no grind or fall off in tone). When I ran the 'calculate accumulator pressure' test protocol yesterday, it peaked at 61 bar and then tapered off to 56 bar within about 10-15 seconds of test stop. Never reached anywhere over 61.

I just ran a voltage test of the clutch control valve (pn 23017845630), the system then said I needed to check ohms across the terminals on the connector, which even without doing, leads me to suspect that part as faulty. Why oh why can't it be cheap parts like relays and plugs that fail?

Anyway, now the car is going back up in the air so I can check that valve and the associated connectors.

Spare a thought for me though, I'm doing all this while it's 99 deg F and about 95% humidity outside...
I've sweated about 10 lbs in the last couple of days!
 
#8 ·
Thanks for the reply,
Quick question, obviously I'm not fully up to speed on this car yet. I was really hoping I'd be able to use it before I had to start fixing it but such is life.
How can I check the accumulator pressure on start up with live feed? Can ISTA or INPA provide it as a read out if plugged in? If so, how can I view it?

To answer your questions, the pump only runs for max 10 seconds on prime, sounds strong and constant (no grind or fall off in tone). When I ran the 'calculate accumulator pressure' test protocol yesterday, it peaked at 61 bar and then tapered off to 56 bar within about 10-15 seconds of test stop. Never reached anywhere over 61.

I just ran a voltage test of the clutch control valve (pn 23017845630), the system then said I needed to check ohms across the terminals on the connector, which even without doing, leads me to suspect that part as faulty. Why oh why can't it be cheap parts like relays and plugs that fail.

Spare a thought for me though, I'm doing all this while it's 99 deg F and about 95% humidity outside...
I've sweated about 10 lbs in the last couple of days!
Yes, always aggravating to get a vehicle and then have problems :( A week after getting mine, I had to replace the steering rack because of a $3 leaking seal (cost me $700 USD and about 20 hours of work to replace the rack ). People always sell them for some reason they don’t want to pay to have fixed it seems.

For the question, I use INPA and in the Analogue Values 1 section you can see the pressure in real time:



https://www.flickr.com/photos/149963117@N03/shares/mezW40



https://www.flickr.com/photos/149963117@N03/shares/98c4ZN

Here, you can watch the pressure cycle as the pump kicks on. Mine pressurizes to 70 bar, then shuts the pump off and does not turn it on again until it drops to 50 bar. With the car idling, you can watch the pressure go up and down. Never tried seeing what the pressure does when you put it in gear or take off though...I should do that to get a baseline for future reference :)
 
#9 ·
You can test pressure accumulator. This test is done by pressurizing (charging) the accumulator and then turning off the SMG pump motor (holding it off) and stroking the clutch numerous times. Given the design parameters of the system, the SMG modules knows it should be able to get "X" number of clutch cycles with a pressure drop to "Y" bar. If not, it assumes the accumulator is bad. This may not be the case however as the other components forming the pressure boundaries of the system can leak and cause faster pressure drop than the design criteria. When this test is run, the clutch valve (both internal spool-to-cartridge clearance and external cartridge o-rings) is the primary pressure boundary. Any leakage on the spool (extremely rare) or the o-rings will present as accumulator precharge loss.
 
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#10 ·
Thanks all! Now I have a series of tests to run and confirm diagnosis.

Small hiccup at the moment, my INPA (from Mikes BMW Tools) wont talk to the car but my ISTA+ will.

Does anyone know where I can find the same readout area on ISTA?

JColley has also suggested running up the pump with the control valve unplugged as that removes signal so should allow the valve to be fully shut to test max system pressure at the accumulator.

I also need to confirm it's not a further wiring fault by checking ohms across the switch so I'll update when I know more.
Any other suggestions?

Cheers!
 
#11 ·
JColley has also suggested running up the pump with the control valve unplugged as that removes signal so should allow the valve to be fully shut to test max system pressure at the accumulator.
Can you point to where Jim recommended that? I believe you may be misreading what he posted. Running the pump with the pressure sensor unplugged (if that's what you mean by control valve) will stress the pump/motor/etc. The hyd diagram shows an overpressure valve, yet not sure why you'd want to run it like this. If it's the clutch solenoid then doing so will harm nothing, but won't test nothing either...

I then checked accumulator pressure static which came up with 28.0 bar preload pressure. The set values show 29-45 bar so this part has reported as faulty. Can accumulators fail as an individual part and if so, can they be replaced as an individual part or must the whole SMG control hydraulic unit be replaced, pump and all?

I went to test the control unit (SMG ECU) but the test didn't respond. I tried ceasing diagnostics twice and re-running the test but still no joy. The only other example I could fund on the forum of fault code 005506 reportedly solved the issue by replacing the SMG ECU so I'm curious to know if this might be the cause which is leading to the Accumulator failing the test due to receiving a faulty signal?

The run tests have show progressively worsening 'Hydraulic pressure - Actual Value' whenever I test (~52-54 Bar instead of ~75 Bar) but I don't know if this is due to the point when the fault code presents or whether the fault code presents because of this?

Sorry for the techno babble. I'd much rather update on my new carbon bits and planned exhaust mods but I'd rather be able to drive the car first in order to do that!

Thanks!
My accumulator is also borderline bad (same as yours 28 bar if memory is right). And it works just fine. You also correctly found the accumulator pre-pressure test, and not the 'other' test that is focused on leaks (number of actuations, etc). You can get the accumulator replaced, but others have done so and fixed nothing. I myself bought a new one when I was troubleshooting a (still) intermittent issue and have yet to install it - no need for it. Car has been perfect for the last 6 months or so.

My thread has some videos of pumps running:
http://www.m5board.com/vbulletin/e6...iscussion/566897-smg-accumulators-go-bad.html


Answer is yes and yes.

If the clutch valve and/or the SMG unit valves are leaking (internal or o rings) the accumulated pressure will of course drop faster than usual, and could lead you think the accumulator is faulty or the pump is weak.

Lack of pressure or pressure holding might come from five reasons only:

Faulty pressure sensor.
Electric motor of the pump worn out (brushes, or coil)
Hydraulic pump worn out (internal leaks)
Accumulator bleed ( the pressure chamber is not anymore sealed)
SMG hydraulic system is bleading internaly or externaly ( Dry O-rings on solenoid valves, worn valves (internal exessive clearance))


You might also check that you have enough fluid in the system. This is apparently often the case that Indies are forgetting to prime the hydraulic pump when refilling the SMG hydraulic unit, and re-top the fluid level, this leads to lack of fluid. If there is not enough liquid the pressure can not build up. That is common sense.

.
Com6 is right on.

I'm a bit confused tho, you said on a separate thread error 506 was smg directional valve, but now the error is 5506. What is the error description in inpa? If clutch valve then you only have 3 choices: wiring, clutch solenoid itself, ecu (in that order I'd add).
 
#14 · (Edited)
Hi all,

Thought I'd wrap this up with the final solution on discovery of the root cause.

I'd heard repeatedly that it might be a mechanical problem (seals, valves, pumps etc etc) so I bought a swath of replacement parts and took the car in with the intent to replace the whole SMG Hydraulic Unit (pump, accumulator, solenoids, valves, reservoir, lines etc). Everything short of the actuators and the SMG ECU. The car drove fine unless the code popped up so it was always a gamble that it was mechanical as they're not typically 'intermittent,' it's either broken or not.

We never got that far. Found an oil leak that was weeping onto the main connector from the ECU to the SMG which had progressively had oil ingress causing crossed signals. Cleaned out the connector, cleared the fault codes and voila!

Deliberately didn't pull the box out to address the leak as I wanted to be sure. Car drove perfectly for 3 months before the code came back so it's going back in the shop to get the box out, leak fixed and have the actuators and solenoid seals re-done while it's out.

The clutch is only 8000kms old now and looks fine so we're leaving that alone.
Anything else to look to preemptively replace while it's out?

I'm also going to finally install my RMS Decat Headers while it's up in the air which should complement the noise from the Eisenmann Race rear mufflers I've fitted nicely!
 
#15 · (Edited)
Car with 122500 km ..smghydro unit is a must.
This car totally not cheap to own and fix.
Enjoy it ,,and glad you are following the issues.
I think this car is a 2006 ,,cos it is build date is September/2006
Thank you.
 
#17 ·
Owned my M5 since october. SMG with 63000 miles now. Ok so two months ago I had the dealer replace clutch and flywheel to get rid of the red cog of death.While in there they also replaced an idle actuator and the rear main seal. Not a cheap visit. Three blocks later the red cog of death came back. Took the car back and after a week they called me and said $10000 more dollars for a hydraulic unit. I told them no and picked the car up and took it to an indie who cleared the code and drove it a few times with no code reappearing. I drove only in p400 mode since and no codes other than the restraint system code. This weekend I put it in p500 and gave it some gusto twice and voila red cog of death is back two days later. Foxwell nt530 says code 5506 clutch valve. I cleared it drove four blocks this morning and it's back. I don't have inpa or itsa and may be getting rid of the car if I can't get some reliability out of it since it's my daily driver. Also had the dealer put in a new battery to eliminate that being the cause. Any ideas would be appreciated. Car seems to be running fine hydraulic unit sounds strong for 9 seconds then cuts off.
 
#18 ·
So first off, your SMG ECU is potentially fried.
Secondly, the cause is potentially the gear sensor wiring (SMG III Gear Sensor Strip Rebuild)
If you have 5506, check through ISTA if you can run the SMG ECU diagnostic test. If the ECU test fails to run or respond, the ECU is shot.
If you have the gearbox out, check the wiring as per the link. My bet is that it's crap too. (common fault often missed)
Good luck!
 
#19 ·
Thanks for the response, one question its driven fine for a month in p400 then seemed to error after I drove it in p500 would that lead you to believe it is indeed mechanical not electrical? I will get ista and see if I can run the suggested test. Thanks for your input.
 
#20 ·
I thought the same. I thought it was P400 vs P500 related, I thought it was worse in 5th and 7th gears, I thought starting the car and having to reverse while cold may cause it. Fact is, that wiring probably caused all of it. Yours may move when shifting hard on P500, causing you to think they're related.
I replaced every mechanical component including the whole actuator tray, pump, all of it. It was the wiring the whole time.
Not sure if there's a way to check the wires while the transmission is in but worth checking. My bet is they're shot.
 
#21 ·
Good afternoon,

Son of krypton - Your responses were appreciated. I still have the M5. Sat in the driveway for a few months and then took it to an indie who is a master mechanic because this car is man vs computer and computer is winning. He ran codes and 5506 came up again. Along with ibs. He asked to bleed the unit again to eliminate that being the issue. He bled it and retaught clutch and it ran for 5 days before red cog and stuck in 1st gear again. He tried running the sequence and it timed out in fifth gear numerous times. He believes like you said it is the wiring so he wants to drop the transmission. He said he ordered the wiring from Germany it will be here in four weeks. He is only charging me 2g to do the job. He seems legit but I have two questions. I don't have ista and my foxwell nt530 sucks. Do you think I should replace 1 or both battery cables? Should I buy a used smg ecu off ebay that has a "working" history? I don't have a lot of money and am thinking if the ibs needs replaced might as well do it anyway. Thanks for your time.
 
#22 ·
Hi mate,

Short answer is that the gearbox should come out. I'd hold off on ordering any new wiring until you get it out either way. I do suggest that you replace the SMG ECU as that simple (and easy) step allowed me to verify that the old one was faulty and that it also allowed us to get past the original code. The second issue that we found having done so was the actuator wiring connecting the shift position sensors to the actuators was pure and utter rubbish from factory. A little digging found that this is a common fault in certain build runs. The shielding for the wires inside the loom there are rubbish and fail completely, leaving a wrapped bundle of exposed trigger / signal wires touching each other (see pic). You can't buy a replacement for this as the whole actuator tray comes as a one piece and the wires and hall effect sensors are matched to the whole assembly (thanks BMW!) The only way to rectify this screw up is to cut and re-sleeve (heat wrap) every individual wire. There are a few really good threads on here about how and why to do this but if yours is like mine was, this is absolutely necessary.

Let us know what you find and how you get on!
940416
 
#23 ·
Alright here is an update. Trans came out again. The wiring you pictured was indeed compromised so he rewired the whole thing and we threw in a new clutch valve controller. 2g for that piece. He put the trans back in and now he can run the shifting sequense with no hiccups at fifth gear so small victory there. However still getting code 5506. He is pulling the smg ecu to dissect its condition. Has anyone used the refurbished ecu pro option? Do you think it is legit? The nice thing is it doesn't require reprogramming the ecu. Cost looks around $500 vs $1200 for a new one.
 
#24 ·
I installed a replacement SMG ECU I bought off eBay. I first bought one from a "professional" who told me it was "fully refurbished" and "as new" which translated into "corroded heap of junk" using my google translator.
So as an interim measure, I found a used one here in Aus on ebay, had it installed the next week and have been running great ever since.
We thought we'd have to reprogram or something before it would work but it worked fine once we ran the ISTA SMG ECU test as part of the service operations list.
Food for thought.
 
#25 ·
Tim5e60,
I just have seen your post.
You spent 2g to replace a part that you didn't even check the signal to or from it. You indie should have done that with Ista or Inap. Ask your indie to screen shot the Analogue value 3 status page from Inpa, the status page for gear position and clutch valve position status page in Ista and post it here.
i will include pictures of them In Inpa you you should have green bars and have black bar represent the reading for that valve.
if you have it full green or full black you have got connection issue before judging to replace the ECU.
when we confirm the signal status, then we can address the fix.
Quick fix is to unplug the connector that hold the clutch valve wiring (the big round connector on the right of transmission) and spray with electric cleaner buff it with air then reconnect also clean the clutch valve connector and check the signal on the status page. If you still missing the signal you need to check for continuity from:
1- Pin 1 from clutch valve connector plug to pin 2 at connector X1 (the big round connector on the right of transmission), then to pin 30 at the SMG ECU.
2- Pin 2 from clutch valve connector plug to pin 1 at connector X1 (the big round connector on the right of transmission), then to pin 28 at the SMG ECU.
At the ECU they will meet at connector M4, it is the one with 40 pin on the right facing the car, check the pins at the ECU for that it is not corroded or broken ECU pins.
 

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#26 ·
SonofKrypton,
In Post #14 you stated that the root cause was a seeping oil into the SMG/ECU connector, cleaning that solve the issue, then later on the following post you point to changing the ECU. I am confused here, what was the root cause, oil ingress into the connector, or changing the ECU. Had you had seen any missing clutch valve signal on ISTA/INPA status page. When did you change the ECU, after the clean up of the connection?
 
#27 ·
It was all a learning experience and trial by fire. I lack a suitably experienced Indy where I live (or one at all) and the local dealer barely knows how to open the door.
We tried everything. Little bits worked at first for short periods, but it was more a fluke than progress.
We tried the wiring connectors and relays first, then the solenoid, then the pump, then the actuator valve, then we replaced the clutch PLCD and the clutch and flywheel, then after all that, the ECU was still failing to respond on ISTA so I replaced that (twice) and also replaced the diff too in case that was somehow related. (PS: I have a spare diff now if anyone needs one). It was only after none of this worked and I was getting ready to swap out all the shift solenoids that I found the connection loom. What a stupid POS problem from BMW. How that **** isn't subject of a recall is beyond me.
Anyway, we re-shielded those and viola! Great Success!

About $10k later and I can officially say the car is for sale if you're interested?
 
#28 ·
So what fixed your problem was the repair for the gear position wiring harness not anything else.
I am looking for the root cause for your malfunction for learning purposes.
In the beginning I thought it was the oil ingress in the big round connector. Then I thought your ECU was damaged and replacing that solved your issue. And now you are saying the gear position harness repair.
What was the last thing you did actually fixed the issue?
 
#29 ·
I'd like to think that if I did the wiring first, I may have not had to do anything else. It's nice to be optimistic.
Truth is, the wires shorting would've played hell with all the sensors, the ECU and PLCD as well as the clutch and diff so it's likely that even if I did the wiring only, the other stuff would fail shortly thereafter. I can't imagine a complex system like the SMG III having such crappy wiring and not causing any follow-on effects. I can't believe it seems to be commonplace and yet people don't seem so upset. It's a truly stupid manufacturing mistake made even worse by the fact that you can't simply replace the part but instead would need to replace the entire shift solenoid tray assembly. You'd think it was designed or manufactured by Apple engineers.
Lots of crappy design bugs and all of it made worse by poor manufacturing quality in certain critical areas, like the SMG and the VANOS system.
 
#31 ·
Platti, saw your troubleshooting recommendations. Thank you! I appreciate the time it took for you to give such a detailed response. I will run it by my indie and see if he still has the run in procedures saved. My indie did replace the harness that you are referring to that has the big connectors. So those are brand new. I believe going off memory that harness also plugs into the new clutch control valve so all those connections are new and clean. He suggested replacing the previous clutch control valve to do it leaking fluid into the connector. He thought the seals inside the valve may have been failing under hi pressure and that was sending fluid through to the connector possibly causing the fault. Now since that is all new and code 5506 is still popping up unless he clears it he believes the only option left is the ecu. Unfortunately transmission is currently back in the car so probing will be extremely difficult. At this point I'm tired of the constant problems and pissed I can't get a used smg control unit to work in the car. There are a ton of them floating around. He says pay $1200 for a new one so as to not have to reprogram everything. I have to go sell a kidney. But again thanks for your response.
 
#32 ·
I am afraid you will lose another 1200$. If you want to follow your indie path and probably waste more money because of poor troubleshooting just follow what he says. Get a used unit for 150$ and experiment his way. If you have ISTA software you can test the valve and the ECU in relation to this particular fault for free, you don't just change every part in the system or subsystem to find a fault. Yes BMW made a high level of equipment but I assure you it also made a high level of a diagnostic software to match that level of sophistication, because it can't just made something and doesn't make a tool to test it, it is not logical, at least for a company as BMW, then we call it unreliable, what is unreliable is the technician who works on this car.
This 5506 fault: Clutch control unit, triggered when the clutch valve value doesn't cross with the values set in the ECU, this happen most of the time intermittently when the clutch closed and no longer be opened, interruption of the signal occurred ( short circuit to power ), or clutch was open and no longer be closed, interruption occurred ( short circuit to power ) , or clutch remains open, interruption occurred ( short circuit to ground ). You need to test continuity from the clutch valve plug to the ECU crossponded connector pins as outlined in my previous posts, wiggle the wires while testing, you can do it while transmission is installed.
Other factors that would set this fault because of implausible values is inadequate clutch bleeding so you need to bleed the clutch at least 5 times providing you have checked the SMG oil level, lastly, you have to make sure you passed the teach-in adaptation ( clutch valve characteristics values ).
If you followed this check list and still you are getting this fault then you can change the SMG ECU only if you can't test it with ISTA.
 
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