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Discussion Starter #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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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.
 

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Discussion Starter #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!
 

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Discussion Starter #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?
 

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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.
 

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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.
 

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Discussion Starter #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!
 

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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/[email protected]/shares/mezW40



https://www.flickr.com/photos/[email protected]/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 :)
 

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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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Discussion Starter #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!
 

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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/e60-m5-e61-m5-touring-discussion/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).
 

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Discussion Starter #12
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).
Thanks for you help and advice,
The error in detail is as pictured on page 1 and is as written below.
Fault Information:
- 5506 Clutch Valve

Possible Fault Causes:
- Line Faulty
- Line has a short circuit to ground/voltage
- Nominal current and actual current implausible
- Clutch branch not adequately bled
- Teach-in for clutch not OK
- Clutch valve faulty
- Control unit faulty

It lists a host of consequences but fails to mention the countless frustrated hours trying to get my dealer to try to fix the problem using something other than replacing everything.

I've checked the lines, no changes there. I also ran the electrical test with no noticeable change in mA when wiggling connectors as instructed. I don't know how to test for the nominal and actual current separately, the clutch was re-bled once already as part of this test and adjust procedure. I've re-taught in the clutch twice now too. That leaves the clutch valve or the control unit but my worry is, will the accumulator still not be able to produce enough pressure even if the valve was faulty once I've replaced it?

In regards to the idea to try disconnecting the clutch valve, the suggestion was to "disconnect the plug to the clutch valve, it shuts fully and will isolate the pump block. Can you see pressure build up fully with the clutch valve electrical plug disconnected? If so, it’s an electrical problem, if not it’s a mechanical problem with the clutch valve."
I thought that seemed pretty sound in logic. My curiousity was how to read the pressure using ISTA+, which I am not Ninja at using.

Thanks again for all the help so far. Crappy that it has to happen over Christmas when I have much better things to be doing.

Merry Christmas all, may your holidays be fault code free!
 

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Thanks for you help and advice,
The error in detail is as pictured on page 1 and is as written below.
Fault Information:
- 5506 Clutch Valve

Possible Fault Causes:
- Line Faulty
- Line has a short circuit to ground/voltage
- Nominal current and actual current implausible
- Clutch branch not adequately bled
- Teach-in for clutch not OK
- Clutch valve faulty
- Control unit faulty

It lists a host of consequences but fails to mention the countless frustrated hours trying to get my dealer to try to fix the problem using something other than replacing everything.

I've checked the lines, no changes there. I also ran the electrical test with no noticeable change in mA when wiggling connectors as instructed. I don't know how to test for the nominal and actual current separately, the clutch was re-bled once already as part of this test and adjust procedure. I've re-taught in the clutch twice now too. That leaves the clutch valve or the control unit but my worry is, will the accumulator still not be able to produce enough pressure even if the valve was faulty once I've replaced it?

In regards to the idea to try disconnecting the clutch valve, the suggestion was to "disconnect the plug to the clutch valve, it shuts fully and will isolate the pump block. Can you see pressure build up fully with the clutch valve electrical plug disconnected? If so, it’s an electrical problem, if not it’s a mechanical problem with the clutch valve."
I thought that seemed pretty sound in logic. My curiousity was how to read the pressure using ISTA+, which I am not Ninja at using.

Thanks again for all the help so far. Crappy that it has to happen over Christmas when I have much better things to be doing.

Merry Christmas all, may your holidays be fault code free!
A-ha, the error description is not on your first post. I take it's the same you posted about on your other thread then. Yeah you could try running it with the clutch valve unplugged. You can use inpa to monitor real-time pressure. It's one of the analog monitors if my memory is right. On ista you'd have to click on the smg ecu and call up it's functions. One option is to read parameters and pressure should be there. Remember the pump is controlled by the ecu, and that pressure target changes (among others) with drive mode and fluid temperature. If your pump is shut off by the ecu then it thinks it's reached the desired target. If the ecu runs the pump continuously then it could be a pump/motor/leak issue. But you haven't mentioned this. The accumulator does not produce pressure, try googling what an accumulator does on a hydraulic system.

Merry Christmas as well!
 

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Discussion Starter #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!
 

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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.
 

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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!

Thank you for the outcome. Always very usefull to have this kind of information on root causes.
And moreover, very glad for you that you cleared your issue.
 

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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.
 

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Discussion Starter #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!
 

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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.
 

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Discussion Starter #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.
 
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