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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.
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.
 

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Discussion Starter #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
 

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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.
 

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Discussion Starter #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.
 

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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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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?
 

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Discussion Starter #27
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?
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?
 

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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?
 

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Discussion Starter #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.
 

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Ok now I understood the root cause was the gear position harness, replacing the ECU didn't solve it.
the weird thing is you didn't have the common fault code for the failed wiring harness, you only got 5506 fault code.
 

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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.
 

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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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