Top wonÂ’t go fully down code A694

[PatrickE89]

As I keep the top-down button the roof folds fine down into the trunk, but the trunk lid doesn’t close to complete the cycle, it remains fully open.
I can hear that the hydraulic motor keeps running after the roof is down in the trunk, but it shuts off after 5-10 seconds.
If I repress down button the hydraulic motor starts but nothing moves.
It works fine to get the top back up from this stage.
I get the feeling that there is a switch or sensor that is not confirming that the roof is in the trunk and not letting the trunk lid to close over the top.

Today I scanned and got fault code A694.

-The battery is fully charged.
-I have inspected the cables and they seem to be fine.

I understand that this code A694 could be bad hall sensor or Micro switch, but I would like to know if someone can know which one it is considering it stops in this specific position.
I'm thankful if someone can point me in the right direction?

[RobbiZ4]

Hi Patrick,

have a look at my following post:
https://z4-forum.com/forum/viewtopic.php?t=130932

Fault codes can be checked here:
https://bmwfault.codes/

Fault code "A694" is "Microswitch 'cowl panel reached'.

[PatrickE89]

Vielen dank Robbi for your advice, now I know where to start!

[PatrickE89]

Ok, so today I started to check some basics with my car. The micro switches left and right seems to be ok, check readings below.
I also inspected the Hall sensor and it looks quite ok, but you never know…

1. Did I check the right micro switches?
2. Any more ideas on what to check next?
3. I learned that the hall sensor is very expensive - Can anyone recomend an online store in Europe, where I can buy the Hall sensor 54377224679 and Micro switches 54377256885?

[RobbiZ4]

Hi Patrick

You've checked the correct MS.

But, the low-value must be 570 ohms (0,57kOhm). Wrong result or typo?

[bigendbob]

See the Hall sensor where you have the green arrow pointing, have you made sure it's connector is fully home. On my car the connector had no means of locking, it just pulled apart slightly. It stopped the roof at point where roof was in trunk, but trunk lid stuck open.
I pushed it fully in, blob of super glue and cable tied each side for good measure, no problem since.

[RobbiZ4]

Originally Posted by PatrickE89

The micro switches left and right seem to be ok...

Unfortunately, this is not so easy to diagnose.

Most faults with these switches are timing issues. Manually switched, they seem to be ok. Mounted in the couplings, sometimes they switch delayed and the CTM will stop it's operation.

[PatrickE89]

Thank you, Robbi - Yes I typed wrong, the value is 0,57kOhm.
I will for sure order 2 new micro switches:
54377256885
54377256886

I removed the Hall sensor and measured it: The reading started at 7,8MOhm that after 2 min. went down to 5,8MOhm. Flipped the wires shows 2,2MOhm solid. Bad?

Thank you Bigendbob for your tip. My sensor appears to be locked in place securely, its actually hard to remove it, but I will follow you advise and secure it with a cable tie.

[RobbiZ4]

Originally Posted by PatrickE89

Thank you, Robbi - Yes I typed wrong, the value is 0,57kOhm.
I will for sure order 2 new micro switches:
54377256885
54377256886

My sensor appears to be locked in place securely, its actually hard to remove it, but I will follow you advise and secure it with a cable tie.

Perfect.

[bigendbob]

I tested some Hall sensors with a 9 volt battery.
I found the current changes if you put in line a voltmeter set to milliamps.
Just pass a steel screw driver over the sensor, the milliamps change.
No voltage change.

[RobbiZ4]

Originally Posted by bigendbob

...the milliamps change.

Correct, that is the general functionality of it. Up to now, I don't know the exact miliampere values for the 2 states (metal/no metal).
Fact is the general problem with the breaking housings: the internal rust changes the magnetic field of the permanent magnet, indirect the miliamperes of the sensor.

[PatrickE89]

Thank you Robbi for your Sunday support!
When you said “Connect both wires on a ~1Mohm range” I did not think and used my multimeter setting for MOhm which is “20MOhm” and got the strange reading of :7,8MOhm that after 2 min. went down to 5,8MOhm.

Today when I used the range “200kOhm” setting I got a more reliable reading:

Hall sensor with Red/Brown wire:
Start value: ~130kOhm, After 3 min: 93,6kOhm, flipped wires: steady 34,3kOhm.

Hall sensor with Yellow/Brown wire:
Start value: ~130kOhm, After 3 min: 94,5kOhm, flipped wires: steady 34,4kOhm.

I assume the Hall sensors are ok? I attach better pictures of the Hall sensor with Red/Brown wire.

[PatrickE89]

And photo from rear

[RobbiZ4]

Perfect!

The electrical results are ok right now. Top.

Pardon, but these photos are not perfect. I still se an indication on the red hall sensor for rust.
If anyhow possible, take an additional, perfect sharp photo of the front side of each hall sensor's fron sidet. The critical area is the upper housing seam on top of the front side.

Any break of the housing is critical. Rust can be identified as a very light yellow color on these seams.

If I'm correct, the red one has already a cut on it's back side.

[bigendbob]

Originally Posted by RobbiZ4

Correct, that is the general functionality of it. Up to now, I don't know the exact miliampere values for the 2 states (metal/no metal).
Fact is the general problem with the breaking housings: the internal rust changes the magnetic field of the permanent magnet, indirect the miliamperes of the sensor.

I bought some 2nd hand, they were fitted originally to Japanese car, but same Hall sensors.
Both cracked. I opened one, no rust.
Both worked when tested.

[RobbiZ4]

[RobbiZ4]

Originally Posted by bigendbob

Both cracked. I opened one, no rust.

In between, I have replaced several hall sensors, which were electrically ok, but didn't work/switch relyable any more. Replaced with a new one, the correct functionality was back.

[PatrickE89]

I will order the two micro switches and see if it works.

[PatrickE89]

and a Hall sensor, just to be on the safe side.

[bigendbob]

Originally Posted by PatrickE89

and a Hall sensor, just to be on the safe side.

Search around the internet, someone found Audi use same Hall sensor, for a fraction of BMW cost. They are used on many vehicles.
Example; https://www.ebay.co.uk/p/835366576

[bigendbob]

Spotted this, part numbers need cross checking;
https://www.ebay.co.uk/itm/324680141...gAAOSw-j1gym4T
Or you take a chance for the cost, the bodies of the sensors look all the same.
I have some in my cupboard from a Japanese car.

When i first had my car i sprayed everything with silicone spray, just knew i didn't want any moisture or rubbing of cables to cause problems.

[bigendbob]

Another that might work, cheap enough to try.
https://www.lllparts.co.uk/en/produc...pn/54347190735

I have just ordered one to experiment with.