Roof fault A696 Hall sensor

[ClumUK]

Maybe I just need to replace both?

Yes, you can.

But, if it's required, is not clear.

You can measure a bit with an ohmmeter:
~33k in one direction
~110k in the oposite direction, stepping down to 60k
These are the values of an dismounted part.

Well yes I'd rather not have to replace both

Just for my sanity this is what I'm seeing:

- Permanent fault on reader, and "Roof movement impaired" when pressing dash button with red flashing light:
A696 Hall sensor, open circuit, closing movement, rear-end module, Fault currently present, Fault currently not present
- I replaced with new the 1st hall sensor mounted at top of boot piston, long cable, yellow & brown wires, white connector. Still get the same error code & message as above:
A696 Hall sensor, open circuit, closing movement, rear-end module, Fault currently present, Fault currently not present
- If I disconnect the 1st sensor I get different message, but still referring to A696:
A696 Hall sensor, open circuit, closing movement, rear-end module, Short circuit to negative
- If I disconnect the 2nd hall sensor mounted at bottom of boot piston, short cable, red & brown wires, black connector. Instead I get different code:
A691 Hall sensor, rear-end module open, Short circuit to negative
- Plugged the old sensor into the 2nd hall sensor black connector block. No change, only get the same A696 error as before:
A696 Hall sensor, open circuit, closing movement, rear-end module, Fault currently present, Fault currently not present

Do you think this likely to be a faulty sensor, or rather a broken wire somewhere else in the harness?

[Smartbear]

If you disconnect the sensor & get a short circuit to negative script, it sounds like a cable fault rather than a component fault.
Rob

[RobbiZ4]

Do you think this likely to be a faulty sensor, or rather a broken wire somewhere else in the harness?

Thanks for all the details.
From my experience, there should not be any wiring problem between the plugs of these 2 HS and the CTM plug. This is a very short connection with separated wires apart of the roof loom.

I will think about it tomorrow...

[RobbiZ4]

Have a look at the following picture to get a better understanding:

20201015_test2.jpg (134.1 KiB) Viewed 139 times

I've done some tests with these hall sensors (HS) on my desk. The right side of this picture directs to the front of the car.

On the right coupling lock, there are 2 hall sensors mounted, each of the same type. The original mounted ones differ in it's wire colour as well as in the lenght of their wires. Spare parts will always be of the same part number as well as the wiring colour and lenght.

The left HS2 (assigned fault code A696) is repsonsible for the 1 second stop of the boot lid while closing, short before it reaches it's closed position.

The right HS1 (assigned fault code A691) is repsonsible to detect the open position of the boot lid.

[RobbiZ4]

Important link to correct fault code descriptions:

https://bmwfault.codes/

FaultCodeTranslator.jpg (100.35 KiB) Viewed 146 times

You have to select the line with the correct ECU variant!

[RobbiZ4]

Initial state:

- Permanent fault on reader, and "Roof movement impaired" when pressing dash button with red flashing light:
A696 Hall sensor, open circuit, closing movement, rear-end module, Fault currently present, Fault currently not present

=> "HS-2"

- I replaced with new the 1st hall sensor mounted at top of boot piston, long cable, yellow & brown wires, white connector. Still get the same error code & message as above:
A696 Hall sensor, open circuit, closing movement, rear-end module, Fault currently present, Fault currently not present

I assume, you've replaced "my HS-1" with a new one from stock?
Then this message is correct, as the initial fault code directs to the 2nd hall sensor.

Disconnecting a single hall sensor doesn't make any sense, as you add another fault. Only replacing a HS with a new or working one does help.

Can you provide a sharp(!) picture of the top of your original hallsensors, like the following one?

20200516_sm.jpg (139.24 KiB) Viewed 140 times

The red marked area is important.

[ClumUK]

Hi Robbie, thanks for all the detailed info! Yes you were right, I had replaced HS1 at first. Instead I replaced HS2 and then all was fixed

I had confused myself with my diagnosis of the error codes, just annoyed now as I cut off the old connector needlessly.
You can see in the picture the issue was probably caused by a cracked casing:

20210615_212302.jpg (55.25 KiB) Viewed 82 times

[flybobbie]

I bought two sensors and cylinder from local scrap yard, they were used on some Japanese or French car.
Close inspection revealed one had cracked.
I found i could test with battery and multimeter, the current changes through them on detection.
The cracked one worked fine.
I broke it open and inside is epoxy encapsulated sensor and magnet.
Must be this epoxy expanding and causing them to crack.

[RobbiZ4]

I found i could test with battery and multimeter, the current changes through them on detection.

As described earlier, it's much easier to test even mounted on the car:

You can measure a bit with an ohmmeter:
~33k in one direction
~110k in the oposite direction, stepping down to 60k
These are the values of an unplugged part.

[flybobbie]

When i tested on bench the best response i could get was the change in current.