Convertible Top issue - Fourth Hall effect sensor????

[edvinpul0805]

Hi Everyone,
I'm a new Z4 owner and new member to the group. I been reading the forums to gain some knowledge and confidence to take some problems but I had to join so I could ask for some help. I have a 2004 E85 Z4.

My, top stopped a few inches from closed position and has not worked since. I had put my had up to protect my kids head as it was closing (shes very impatient) and barely put any pressure on the roof ...maybe coincidence.

Persistent Error: CVM: Switch, cowl panel unlocked, short circuit to ground

Current State: Red flashing light, open/close buttons do nothing (as in not hydraulic pump action) - but they do work (confirmed with scanner).

Day 1 Troubleshooting:
1. Removed the cowl to inspect the sensor/motor cabling for breaks as per this forum - all good...just a kink
2. While working, I disconnected the hall effect sensor (HES) (attached to the cable above)
and re-scanned car and got a second error CVM: Switch, cowl panel locked, short circuit to ground
3. Connected HES and second error is gone.
4. Manually close the top and close the locks with allen key. When fully closed, I get "implausible state" on my scanner
5. I'm pretty sure the trunk micro-switch is working.


Day 2 Troubleshooting:
I was convinced the sensor on the hydraulic ram was the issue.
1. Opened up the drivers side (North America - Canada ) to inspect the hall effect sensor.
To my surprise there were 2 - one facing the side, and one facing up.
When both are unblocked by metal, my scanner states the convertible is in "Intermediate Position"
When the one facing up is blocked with a piece of metal, scanner states "closed"
When the one facing sideways is blocked with a piece of metal, scanner states "stowed"
When both are blocked, it stats "implausible"
These sensors appear to be working.


I have a blurry drawing of the convertible top wiring and I believe there is a 4th hall effect sensor somewhere
that I'm missing...any help would be appreciated

Eddie

 

[Number5]

The top hall sensor of the two, is the one that tells the hydraulic pump to stop and the claws to begin locking
The sideways one, tells the roof ECU to stop the hydraulic pump, as the roof is stowed (in the boot/trunk)
Normally you would never have both of these activated by the presence of the metal frame at the same time, ( hence the Implausible state)

If you cover the top sensor when the roof is only part way up, you’ll notice that the hydraulic motor stops and the claws start locking, even tho its not reached the windscreen

There is another hall sensor on the drivers side (USA) claw, so the ECU knows if its open or locked.
The fourth sensor may be the parcel shelf micro switch, even tho its not really a hall sensor

 

[edvinpul0805]

So there are only 3 hall effect sensors and the microswitch?

From what I've learned, there are three positions/states (not sure if names are the same across different code readers)
1. Stowed (while roof is open)
2. Intermediate Position (while traveling)
3. Closed (windshield position)

During these three positions, the Locking Hook state is "unlocked" on my scanner

As you have said, the hall effect sensor (pointing up) will trigger the cowl motor to engage the hooks. Mine won't right now so I'm force to use an allen key. When I fully engage the hooks (feels like too much resistance on the hex screw), the Locking Hook state is "Implausible"
How do I test this sensor in the cowl. I ran my channel locks across the drivers side top (USA) but could not trigger it. Does the hook itself trigger the sensor when its engaged?
What I haven't wrapped my head around it that when I disconnected the sensor in the cowl during my first attempt at this, I got the second error
CVM: Switch, cowl panel locked, short circuit to ground. It seems like there are two states, locked and unlocked are conflicting - like I was able to recreate with the two sensors by the hydraulic cyclinder.

I was able to make out the following names of switches from the manual - according to AI The term "scuttle" is a holdover from British automotive terminology (originally referring to the cowl or fire partition on older cars).

Convertible Top Lowered Switch (i assume the side pointing hall effect on hydraulic)
Scuttle Release Switch (Switch, cowl panel unlocked, short circuit to ground - the error that never clears)
Scuttle Locked Switch (I think the one I was able to disconnect to trigger the "Switch, cowl panel locked, short circuit to ground."
Convertible Top Switch Closed (i assume the Up pointing hall effect on hydraulic)

The drawing I have is from the 2005 Z4 where mine is the 2004....not sure if there was an electrical change from 2004 to 2005

Could there be a complimentary hall effect sensor somewhere in the roof cowl and I just have not found a break in the wire?

 

[edvinpul0805]

I found this on https://charm.li manuals - looks like there are two hall effect sensors in the cowl. I think they must be on the drivers side (USA) locking mechanism. I guess my next move is to take a closer look at the cable harness...there must be a broken or shorted wire along the path, no?

 

[edvinpul0805]

Hi everyone, posting this as a possible help to someone else with similar issue - I'm sure this is found somewhere on the interwebs, but I never came across it.
There are two hall effect sensors on the convertible top locking mechanism - for each the 'locked' and 'unlocked' state. One leg of each sensor is tied together to a common red/yellow wire (+V). Each other leg has a respective wire. For 'unlocked' its the brown/yellow wire and the 'locked' signal is the black/red wire. I eventually found a break in the brown/yellow wire where the hinge meets the door/pillar. I ran three new wires from the pillar to the sensor connector. Errors are gone, hi-fives all around, and I'm excited to try it....happiness is short lived.
My top is acting crazy! Open button causes the door to close and the close button does the opposite. If i get it to open, then I can't get it to close, even manually, because it latches itself shut!. When I get the top to approach the windshield, the hinges are in a closed position and hit the lock. Has anyone seen this before? I'm 100% confident in my wiring because I cut each wires (a second time) at the splice points and I got the errors I was expecting in my scanner - a little extra effort but I was beginning to doubt myself.