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Discussion Starter #1
I have been trying to fix this problem consistent with this code 4F43 and this code will only happens while the engine running for extended period of time and eventually I will get 4F40 hydraulic unit, pressure band undershoot that’s responsible for shutting down the transmission and send it into Neutral.

What I did so far:

Installed new electric motor
Installed new hydraulic pressure sensor
Installed new SMG Relay
Tried top up expansion tank

None of which fixes the problem

I tried performing 3 steps adaptation and failed all tests stating hydraulic couldn’t reached target pressure in time or hydraulic pressure too low.
 

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Discussion Starter #3
I am not sure how I can tell if the accumulator holding pressure consistently however I did a pre-charge accumulator pressure test. It is always within the set point value. 36 to 37 bar that was after I installed a new pressesure sensor, before that with the old pressure sensor it was always settled at 32 bar but still within the specification.

When I did pressure built up via ISTA, it inisits hydraulic pressure sensor is the culprit however that doesn’t seems to fix the problem, except I didn’t replaced it with the same part number because pressure sensor with SMG transmission for 2007 640i or 325CI not M model look exact same to M5’s, and the car seems to registered that sensor.

So frustrating, I wish it was simple as replacing the SMG relay or fuse.
 

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Since you mention pressure sensor this sounds somewhat related to the software update required for early builds. You are however getting a different code:


Now failure to complete adaptation usually points to a clutch failure requiring trans to come out (leaking slave, broken pressure plate, etc).

What's the max pressure before pump shuts off? Any unusual noises with your pump? Maybe a video showing pump running while monitoring pressure would help diagnose.
 

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There's a check valve after the pump within the hydraulic block so a leaking pump can't be the cause for not holding pressure. Now failure to reach pressure could certainly be a leaky pump although I don't recall having heard of such a failure yet. You will hear the pump motor run longer / forever - note forever could also be due to low fluid. Could be leaks elsewhere too.

$200 for 5 orings shipped to the US is tough to swallow.
 

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I remember when I just bought my car, on way home after around 30miles I stuck with red cog, car been towed back to dealership and they replaced pump motor, after few days I took my car home again and after around same distance I stuck again with red cog unable to get home for second time on my new car. This time they said pressure accumulator need to be raplaced due to pressure lost. Unfortunately this didn't made any difference car got red cog again in 20 miles. I was about to demand my money back, but this was only sepang bronze on the market at the time and I decided to give them last chance. This time they replaced this seal kit from above link, and no problem since then. Old seals was not able to keep pressure once gearbox was up to hot temp.

Sent from my LYA-L29 using Tapatalk
 

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Discussion Starter #9
Since you mention pressure sensor this sounds somewhat related to the software update required for early builds. You are however getting a different code:


Now failure to complete adaptation usually points to a clutch failure requiring trans to come out (leaking slave, broken pressure plate, etc).

What's the max pressure before pump shuts off? Any unusual noises with your pump? Maybe a video showing pump running while monitoring pressure would help diagnose.
The pump would build up to 85 bar as that is the shutoff point then drop down to 81 for a little while and while I wait awhile it would drop back down to the normal range 50 to 70 bar.


Here’s a video of the pump running:
 

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Discussion Starter #10
If system does not hold the pressure you might need to replace this seal kit


Sent from my LYA-L29 using Tapatalk
I linked a video of what the pump sound like when I commanded it to build up pressure. Can you tell if this part might alleative the issue based on this video alone?


When I removed the pump from the electric motor without dropping the transmission, I didn’t notice fluid emerge out of the pump. Perhaps, I may have missed it.
 

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Discussion Starter #11
There's a check valve after the pump within the hydraulic block so a leaking pump can't be the cause for not holding pressure. Now failure to reach pressure could certainly be a leaky pump although I don't recall having heard of such a failure yet. You will hear the pump motor run longer / forever - note forever could also be due to low fluid. Could be leaks elsewhere too.

$200 for 5 orings shipped to the US is tough to swallow.
I tried to top up the expansion tank but fluid keeps on coming out as if there is no need for additional fluid. I went great length to changed the fluid to new one. Issue still persists.

When I removed the electric motor, and it was necessary to remove the pump in order to remove the electric motor. Interestingly, I didn’t notice any leaks emerged from the pump, per se. I post a video of what the pump sounds like when building pressure to 80 bar.
 

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My SMG was sorted when I bought my car as per my previous post, and I never touch it again, so I got no experience to advise you on your video

Sent from my LYA-L29 using Tapatalk
 

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Discussion Starter #13
I remember when I just bought my car, on way home after around 30miles I stuck with red cog, car been towed back to dealership and they replaced pump motor, after few days I took my car home again and after around same distance I stuck again with red cog unable to get home for second time on my new car. This time they said pressure accumulator need to be raplaced due to pressure lost. Unfortunately this didn't made any difference car got red cog again in 20 miles. I was about to demand my money back, but this was only sepang bronze on the market at the time and I decided to give them last chance. This time they replaced this seal kit from above link, and no problem since then. Old seals was not able to keep pressure once gearbox was up to hot temp.

Sent from my LYA-L29 using Tapatalk

This is interesting. Did your car prompted yellow “cog” transmission warning first then eventually prompted red “cog” transmission where it would shut down your transmission and put it in neutral because this what mine does.

For my yellow “cog” transmission warning is code 4F43-Hydraulic unit, on period

For my red “cog” transmissions warning is code 4F42: Hydraulic control unit: activation frequency, pressure build-up.

I think the part you mentioned is interesting because while I keeps the engine running for a while and that’s where the hydraulic starting to get hotter and hotter. The yellow cog tranmission warning seems to prompted at 47 to 50 temperature.

I am going to double check at what temperature I get yellow cog and what temperature for red cog.
 

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Discussion Starter #14
This is interesting. Did your car prompted yellow “cog” transmission warning first then eventually prompted red “cog” transmission where it would shut down your transmission and put it in neutral because this what mine does.

For my yellow “cog” transmission warning is code 4F43-Hydraulic unit, on period

For my red “cog” transmissions warning is code 4F42: Hydraulic control unit: activation frequency, pressure build-up.

I think the part you mentioned is interesting because while I keeps the engine running for a while and that’s where the hydraulic starting to get hotter and hotter. The yellow cog tranmission warning seems to prompted at 47 to 50 temperature.

I am going to double check at what temperature I get yellow cog and what temperature for red cog.
My SMG was sorted when I bought my car as per my previous post, and I never touch it again, so I got no experience to advise you on your video

Sent from my LYA-L29 using Tapatalk
My SMG was sorted when I bought my car as per my previous post, and I never touch it again, so I got no experience to advise you on your video

Sent from my LYA-L29 using Tapatalk
My SMG was sorted when I bought my car as per my previous post, and I never touch it again, so I got no experience to advise you on your video

Sent from my LYA-L29 using Tapatalk
I am glad you got it sorted. It would be nice if the fix is simple.

I can’t perform a test at the moment because the car stuck in “N” right now as the pump is shut off and would not pump up pressure at my command at 47 c temperature So I am going to let the hydraulic system to cool off then I will test it again.

Do you happen to know what’s gearbox operating temperature?
 

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Your pump sounds fine and builds pressure correctly. Doubt it's the orings.

How are you keeping the battery charged when running adaptations? If voltage gets too low then it will fail.
 

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Discussion Starter #18 (Edited)
Your pump sounds fine and builds pressure correctly. Doubt it's the orings.

How are you keeping the battery charged when running adaptations? If voltage gets too low then it will fail.
When I first tried to perform adaptations upon receiving 4F43, on a battery tender for clutch, it takes long time to finished clutch teach-in as it should takes 3 minutes max according to ISTA but it runs forever and I just clicked continue and it saves the teach-in but I got red cog “adaptation-clutch active” on dash then I tried to perform transmission teach-in, failed stated hydraulic pressure too low” red cog on dash stating perform transmission adapt and tried to bleed actuator, I think that’s what it called, failed because can’t reach target pressure in time and I tried with another car running to have this m5 charge above 13 v and that doesn’t make a different.
 

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Discussion Starter #19 (Edited)
Your pump sounds fine and builds pressure correctly. Doubt it's the orings.

How are you keeping the battery charged when running adaptations? If voltage gets too low then it will fail.

One more thing, when I switched on the hydraulic pump via INPA, to have it build up pressure but once it is at 76 bar and I quickly start the car, the car fire up right away, normally in the low 50 to 62 pressure especially when the car is at terminal 15, it feel like the car struggles to start up. It hard to explain because struggle is not the right word, the car would start every times but at a slow rate either with new battery or old but above 70 the car would fire up right away when I forced the hydraulic pump on. I don’t really know what’s the normal hydraulic pressure necessarily to start up the car that feels in conform with other cars that gives instant car start nor I know or recall if this is normal for E60 M5
 

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Discussion Starter #20
One more thing, when I switched on the hydraulic pump via INPA, to have it build up pressure but once it is at 76 bar and I quickly start the car, the car fire up right away, normally in the low 50 to 62 pressure especially when the car is at terminal 15, it feel like the car struggles to start up. It hard to explain because struggle is not the right word, the car would start every times but at a slow rate either with new battery or old and is something that I just began to notice but above 70 bar, the car would fire up right away when I forced the hydraulic pump on. I don’t really know what’s the normal hydraulic pressure necessarily to start up the car that feels in conform with other cars that gives instant car start nor I know or recall if this is normal for E60 M5
 
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