M5 Solenoids

[avlnch]

Anyone know what model years need Solenoids replaced, and around what mileage? What are the early and late symptoms?

I have a 03.13 F10 M5, and sometimes the DCT doesn't respond to a shift command. Takes a few times until it responds.

Wondering if it may be the Solenoids? Or maybe something else, not sure.

What exactly do the DCT's Solenoids do?

[boots]

Solenoids are a eletric operated item. When a signal is present it measures it and sends a signal. That signal tells whether something is there and pressure gain/loss. There will always be a delay.. In one of our case, it probably operates a shuttle valve which is an open/close item. Mine were replaced I think around 4k miles when I had a drive train Mal. It seems that all of us have problems with the oem solenoids. After replacement, you shouldn't have a problem. If someone else can help explain please do.

[CFisher]

Solenoids are my line of work. That's about all I do some days! Total Speculation Follows - Not sure how they're implemented in the DCT but I'm guessing we're talking electro-mechanical units here probably valves or could be as @boots points to - an indicator of sorts within the mechanism (though a traditional solenoid is a coil driven by applied voltage) - computer sends command->power supply sends voltage->solenoid valve energizes->tranny shifts. Usually milliseconds. Gum the works up with a faulty seal or poor alignment or 20 other things and solenoid won't work as intended - may get stuck in a position that shorts the internal coil etc.
Unfortunately I can give a dissertation on solenoids...just not anything in particular about how they apply to our M5!

[boots]

Thanks bro. I have them on my subsea control modual and can explain them really well, but fall short for this topic thanks. But the dealership can read the voltage which should read about 24v.

[Boss330]

Originally Posted by boots

Thanks bro. I have them on my subsea control modual and can explain them really well, but fall short for this topic thanks. But the dealership can read the voltage which should read about 24v.

How can they read 24v on a 12v system??? There are plenty of 12v solenoids out there, so I would assume they use a 12v solenoid on a 12v system...

And usually a solenoid isn't pressure operated, but operated by electricity. It might regulate a pressure circuit by opening or closing a valve. Solenoids are used in such diverse applications as central locking systems and remote trunk opening by simply opening or closing the lock mechanism.

In the DCT I would think they are used to open and close hydraulic circuits that operate the clutches and gear shifting. Solenoids are fast acting and can go from one position to the other really quick.

[JOHNBMWM5]

Originally Posted by Boss330

How can they read 24v on a 12v system??? There are plenty of 12v solenoids out there, so I would assume they use a 12v solenoid on a 12v system...

And usually a solenoid isn't pressure operated, but operated by electricity. It might regulate a pressure circuit by opening or closing a valve. Solenoids are used in such diverse applications as central locking systems and remote trunk opening by simply opening or closing the lock mechanism.

In the DCT I would think they are used to open and close hydraulic circuits that operate the clutches and gear shifting. Solenoids are fast acting and can go from one position to the other really quick.

This is correct .

[boots]

Typo bro! 12v!

[AlphaAlpineM6]

Originally Posted by CFisher

Solenoids are my line of work. That's about all I do some days! Total Speculation Follows - Not sure how they're implemented in the DCT but I'm guessing we're talking electro-mechanical units here probably valves or could be as @boots points to - an indicator of sorts within the mechanism (though a traditional solenoid is a coil driven by applied voltage) - computer sends command->power supply sends voltage->solenoid valve energizes->tranny shifts. Usually milliseconds. Gum the works up with a faulty seal or poor alignment or 20 other things and solenoid won't work as intended - may get stuck in a position that shorts the internal coil etc.
Unfortunately I can give a dissertation on solenoids...just not anything in particular about how they apply to our M5!

Ph.D in electrical engineering?

[Spinny02]

Hope you get its right. Let u snow what you find out.

[avlnch]

So this is easy to test? Either the Solenoids are good (12v) or bad (under 12v)? Does the dealer have to take anything apart to test?

I try not to say there's a issue unless it's a constant or near constant recurring problem. 98% of the time the car shifts no problem. Rarely I am seeing a delay or no action at all.

If it's easy to test I'll ask for that to be done next oil change.

[Boss330]

Originally Posted by avlnch

So this is easy to test? Either the Solenoids are good (12v) or bad (under 12v)? Does the dealer have to take anything apart to test?

I try not to say there's a issue unless it's a constant or near constant recurring problem. 98% of the time the car shifts no problem. Rarely I am seeing a delay or no action at all.

If it's easy to test I'll ask for that to be done next oil change.

It's probably even easier to check than that... It has hopefully thrown a error code that can be read through the diagnostics system. Quite likely a stored code or a pending code.

The 12v thing is just the voltage going to the solenoid. If the solenoid suffers from a mechanical fault, there won't be any electrical faults detectable. But if the solenoid sometimes get stuck/slow, it will likely still throw a code as the command from the ECU doesn't lead to the desired action from the DCT.

Have your dealer do a diagnostics on the car and he should be able to see any codes in 5 minutes.

[avlnch]

Originally Posted by Boss330

It's probably even easier to check than that... It has hopefully thrown a error code that can be read through the diagnostics system. Quite likely a stored code or a pending code.

The 12v thing is just the voltage going to the solenoid. If the solenoid suffers from a mechanical fault, there won't be any electrical faults detectable. But if the solenoid sometimes get stuck/slow, it will likely still throw a code as the command from the ECU doesn't lead to the desired action from the DCT.

Have your dealer do a diagnostics on the car and he should be able to see any codes in 5 minutes.

That's what I was wondering about.

^^^^^ Thanks for the info & replies

[Boss330]

Originally Posted by boots

Typo bro! 12v!