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Discussion Starter · #1 ·
Hi,
I just got myself a 2012 981 2.7 Boxster and so far been really happy with it! My last Porsche was a 996tt that I built with a lot of Cup and GT2/GT3 parts into a great 500hp rwd track car but unfortunately it was not that great to drive on the street anymore. Something this Boxster with PDK, PASM etc absolutely is, so effortless and smooth! :)

With spring approaching I ran into a problem though, my top wont open! When I got the car this winter I tried it once in the garage but after a few weeks without the battery connected due to replacing it it wont open anymore. It will release the latch in the rear view mirror but then nothing happens and no errors in the display. I tried to open it manually just to make sure that it was not stuck but that was fine.

Yesterday I did a quick search with Piwis 3 and saw the fault codes 001001 and 001006 which means that a temperature limiter in the top motor 1 and 2 is open/active. Could not find any way to reset though.

Does anyone have experience with this problem and know how to reset the temperature limiters?
(Piwis suggested to replace the convertible top control unit but I dont really see why it would need replacing.)

Thanks,
Tom
 

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Discussion Starter · #2 ·
(Piwis suggested to replace the convertible top control unit but I dont really see why it would need replacing.)
Sorry, my bad. It was not really suggested by Piwis, just my interpretation due to being a beginner with Piwis.

I was able to clear the fault codes but they reappear immidiately unfortunately.
 

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Discussion Starter · #3 ·
Available info in Piwis regarding the fault codes. Still not really clear to me on what to do for the next step.

D9123084-542B-4314-B463-D9EC6E2E5901.jpeg
 

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Looking at the wiring diagrams, there isn't a thermal sensor, but there is a motor sensor on each motor that has separate wiring from main plug. This might be a thermal sensor. Is there a motor temperature that can be seen under actual values in PIWIS?

Each motor has plug with 5 wires going to it (first wiring diagram showing the two motor wires as well as the three for hall position sensor). It also has another plug with two or three wires (second wiring diagram showing the 'motor sensor')

To have two components fail simultaneously would be very unusual. Most likely a common fault, so I'd be looking for a common issue for both sides.

For each of the hall sensors there is a common negative, X902. That would be the first place I would investigate. The convertible control unit is to the left of the engine control unit in the car boot under the trim. I'd be unplugging/replugging everything and tracing to the ground point (left side of the compartment) to ensure that's all OK as a first step.

If all that seems OK, I'd be looking at the connections on the second wiring diagram, that being from the motor sensors to the Rear BCM. The ground for the Rear BCM as you can see is under the left seat (I think it's actually at the back left of the cabin behind the noise insulation). I'd be surprised if either of the the ground connections at the chassis would be the issue, as you would have many other issues with the convertible module and Rear BCM. The plugs and general wiring condition is where I'd be looking as a start.

274211






274217
 

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Discussion Starter · #6 ·
Thanks a lot for your support! (y)
(Great work also with the YouTube channel, it is much appreciated.)

The only temperature is just the outside temp, none for the motors.
Checked everything in the rear trunk regarding connectors to the control unit and grounding. Everything looks fine and the problem is still there. Also removed pieces in the coupe so I could have a peek at the motors, cables and connectors but everything looks fine. Did not have the time to check BCM under the seat yet.

I don’t think there is any damage to cables/connectors or bad grounding as far as I can see but could any damage have occurred to any control units when I first got the car and operated the roof with a bad battery where I got that warning to light up in the cars display?
 

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My interest in your problem had me connect my PIWIS and see what actual values came from a roof that was working normally. I just wanted to learn what was going on.

Below is a screenshot with some markup in red of what each of the values means. It's not particularly intuitive. It's with the roof in the fully down position.

Are you getting values for all of these? If not then it might point you to the problem.

I also wrote some notes from what I observed, as I can guarantee I won't remember them in the future when I might need them. They are below as well.

BCM connections:

Hood latch hood switch (in the windscreen frame)
Reed switch detects the hook is hooked into the windscreen latch
Microswitch detects when the hook has been removed

Hood latch sensor (on hook motor assembly)
Detects if the hook is in the fully extended or fully retracted position
Two microswitches with common ground. One switch for each position.

Convertible top micro 1:
Up = Yes
Nearly Up = Yes
Mid = No
Nearly down = No
Down = Yes

Convertible top micro 2:
Up = Yes
Nearly Up = No
Mid = No
Nearly Down = Yes
Down = Yes

CVM connections:
Motor hall sensors show the position of the motor. Roof down = 2000, roof up = 1000

When moving roof, this shows a continuous change between the two values as expected from a hall sensor. When initially roof fully down, value was about 1850, but then after about 1 sec value went to 2000, as other indicators show the roof is fully down. When raising roof, value went to about 1040, then jumped to 1000 after about a second when other indicators confirmed roof fully up.

274235
 

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Discussion Starter · #8 ·
Again, thanks a lot for you commitment! (y)
I will be away from the car until monday unfortunately but look forward to comparing some values once back.
(I only remember motor position being "1000" as it should with the roof up.)
 

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No problems. I'm really enjoying the learning.

With PIWIS attached it might be worth moving the roof in manual mode to see what it gives. Just remember to retract the hood prior to lowering the roof down if you choose to do this.
 

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Discussion Starter · #10 ·
Back again and checked some values!
Some difference regarding what is shown between my Piwis 3 and your (I assume) Piwis 2 but most seems to be the same and ok. Voltage is about 2 V lower but I assume you had you motor running due to the high value?

All other sensors seem ok, buttons work which I can see from the values when activated. Motors show 2000 with the top lowered manually.

I disconnected the connectors to the motors and got the fault code for hall sensors as well:
DE8A8811-FF4A-41DE-BEF0-D47DA9B44F82.jpeg




Tried at the connector to measure the resistance of the motor sensors but no luck (infinite). It would be interesting to know if should be possible. If it really should normally be a closed circuit I could just try to short circuit as a test. A bit strange if both would break/open at the same time though.



9EB38F2C-AF73-4744-8EA2-20836806BC28.jpeg
916C2CE0-4E53-442C-A46D-57E3A92A3BEC.jpeg
 

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Discussion Starter · #11 ·
Did some more measuring today:
  • From Rear BCM there are 12 Volts output with ignition on between the sensor ground and ‘signal’, ‘signal 1’, ’signal 2’.
  • Measuring on the disconnected motor and sensor connector there is infinite (open circuit) resistance between ’signal’ or ‘signal 1’ and ground. Between ‘signal 2’ and ground there is a closed circuit (short circuit).

I would greatly appreciate if anyone could measure the following on a healthy car:
1. Disconnect the hood motor connector behind the carpet behind the seats, located just where the seatbelt units are. See the pictures above on my car.
2. On the connector going to the hood motor (towards rear of the car). Measure resistance between ground and ‘signal‘ as per the wiring diagrams above. Brown/Blue being the ground and Brown/Grey as well as Brown/Red being the ‘signal’.

Thanks,
/Tom
 

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Discussion Starter · #12 ·
Tried to short circuit the sensors but the fault remains the same... :confused:

Here‘s hoping that someone can do the measurements as above to a healthy top. Gettin a bit desperate now!
🧐
 

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I didn't see the other posts about values a few weeks ago and only just saw the last post now. I've got the day off tomorrow so I'll go and have a play.
 

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I had a bit of a play today and another good look at the wiring diagrams to see if I can get a grip on what is going on.

Look at the two wiring diagrams below. The first are those connections to the rear BCM, and the second to the convertible module.


Rear BCM wiring
274677



CVM wiring
274678


Red circled on both is the plug that you have disconnected in the photos in the above post. X260 is the plug on the left (the one in your photo) and X265 is the plug on the right. The pinout on each of these is the red arrow. You notice that it's the same plug on each wiring diagram, meaning that all the wires coming from the convertible motor area on each side go to the same plug, but then some go to the rear BCM and the others go to the CVM.

The way the system seems to work is that the roof motor and hall sensors go to the CVM, and the E Hood motor sensors go to the BCM. From what I can see, the E Hood motor sensors are there simply to tell the BCM when to open and close the hook that connects to the windscreen, as this is what the BCM is doing.

Also notice that in the top wiring diagram for the BCM, 'signal' on the right E Hood sensor and 'signal 1' on the left E Hood sensor are the same circuit. They are connected so that if either sensor closes the circuit, then the circuit is close, but both need to be open to have the circuit open. They seem to backup each other. 'Sensor 2' is a separate circuit. In my post above where I looked at the state of each of the 'convertible top micro 1/2', it's clear to me that the 'convertible top micro 1' circuit is the 'signal and signal 1' circuit, and 'convertible top micro 2' is the 'signal 2' circuit.

I did a bunch of testing of these 'signal' circuits at different roof positions, moving the roof manually and the plugs disconnected.

'signal' and 'signal 1' give identical responses.
'signal 2' is slightly different.
The response from PIWIS for each of these equates to what I wrote in the post above. 'Yes' = open circuit. 'No' = closed circuit. All the signal circuits are tested to the adjacent 'ground' pin.

So repeating what I had above with this included

Convertible top micro 1: (signal and signal 1)
Up = Yes = open circuit
Nearly Up = Yes = open circuit
Mid = No = closed circuit
Nearly down = No = closed circuit
Down = Yes = open circuit

Convertible top micro 2: (signal 2)
Up = Yes = open circuit
Nearly Up = No = closed circuit
Mid = No = closed circuit
Nearly Down = Yes = open circuit
Down = Yes = open circuit

What is clear is that for each the circuit is open when the roof is fully up or fully down. It only closes the circuits when in a mid position. This mid position that closes the circuit is different for each, and I expect is telling the BCM the limits of where the hook needs to be either fully extended or retracted when either lowering or opening the roof.

For the CVM circuits, infinite resistance is shown for all of the hall sensor circuits regardless of roof position. There is close to zero resistance for the motor circuits.

So how to find out what's going on in your roof. This is what I would do.

Hook up your PIWIS so you can see the appropriate actual values for the rear BCM and the CVM.
Unlatch the hook connected to the windscreen manually. Once unhooked, retract it so it's not sticking out.
Unlock each motor so you can move the roof manually.
Move the roof by hand and see what the response is from 'position motor 1/2' (the hall sensors), and the response from the convertible top micros.

For me, this is the only way you are going to work out what is working correctly and what isn't.

Last thing, when I was playing this morning I ran into a strange issue where the roof wouldn't move, it was saying there was an error in the CVM (on the MFD on the instrument cluster), but there were no codes in either the BCM or CVM and the roof wouldn't move. Only way to fix was to disconnect the battery for a few minutes and then reconnect. All was fine after. Maybe worth a shot if you haven't done this already.

Hope this helps
 

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Discussion Starter · #15 ·
Great, thanks a lot for the input! I will do some actual movement of the top with the Piwis in place and a multimeter to see if I get the correct values.

(Already tried to disconnect the battery but no luck so far. My problem is also that I have got the fault codes that will come right back after clearing.)
 

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Discussion Starter · #17 ·
I did some further testing with the top in manual. Hook operated by its motor which seems to work fine and also the sensor values for it.

When comparing to your measurements (again, a big thank you for all support!) I see 2 things that differ:

1). I don’t get the values in between 1000 and 2000 for the position of the motors. It goes straight from 1000 to 2000 and vice versa for the end positions.

2). Signal 2 is a closed circuit with the top up as highlighted below. Something must be wrong here. In the other positions it seems to be the same as for you.

Convertible top micro 1: (signal and signal 1)
Up = Yes = open circuit
Mid = No = closed circuit
Down = Yes = open circuit

Convertible top micro 2: (signal 2)
Up = No = closed circuit
Mid = No = closed circuit
Down = Yes = open circuit

As the sensor changes value it seems to me that it might be out of position? Unfortunately it is not so easy to get a good view of the motors and its surrounding parts.. ;)
 

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I must admit I also couldn't get the change in hall sensor values when moving in manual mode. At the time I didn't know if it was due to the other error I talked about that finally cleared. To be honest I stopped testing after I got it working again as I was just happy I'd solved the issue.

Do you have a workshop manual? There is a procedure for removal/install of these microswitches.
 

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Discussion Starter · #19 ·
I did an additional test this morning:
As the sensor values with the top fully down where the same as for you I lowered the top in manual mode and cleared the fault codes. After that I reconnected the motors with the 13 mm spanner and tried to operate the top but as soon as it were supposed to operate the top motors nothing happened except that the fault codes reappeared...


I might as a next step try and disconnect one motor from the 'gearbox' and its electrical connector and feed it with a fused 12 V source just to see that I can get it to spin.

Regarding the microswitches I got the 6000 pages workshop manual and have seen this on Youtube a few times but will investigate a bit further first in order to avoid this quite substantial teardown... 😁
 

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Discussion Starter · #20 ·
Ok, fed 12 V straight to the disconnect motors and they worked fine. A little bit strange that the right side measured 5 Ohm and the left 50 Ohm but both behaved the same with 12 V.

Sensors on the latch seems to read fine but I guess that is the next step to check since they are easy to access. After that I guess it is the control module in the rear trunk or the switches that a lot of people seem to have problems with that are hard to diagnose.
 
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