⌛Y3 & Y4 Roof Diagnostic System (for all convertible & roadster)

Before it get's lost in the discussion section, I will place a link into this How-To section:



The whole story:

⌛Y3 & Y4 Roof Diagnostic System (for all convertible & roadster)

The 3rd generation of my roof diagnostic system got finished in these days, after a conceptual phase of about 2 years: Just have a look at some pictures on the German ZRoadster forum of the final build phase. 🤣...

z4-forum.com

Another interesting E89 roof EKG as of today.

Continuous alerts on the dash and bongs regarding a roof issue. Unfortunately during a 400km drive.
There were no fault codes to find on OBD.

First of all:
The sensors in our Z4 roof have 2 valid states, HIGH or LOW, represented by ~2.0V or ~0.5V in my EKG charts. Any discrepancy indicates a (temporary or permanent) error.

EKG extract of the two microswitches coupling lock in the trunk (MS KV LI = left, MS KV RE = right):


Unusually the "jittery" signal from the left microswitch coupling lock, represented by the green line on the chart.
The voltage of about 1.28 V on the green line is completely wrong, but the signal from the right microswitch (blue line) looks perfect. Both signals seem to change their states synchronously from LOW to HIGH or vice versa.

Switched between an external attached microswitch [left red box] and the internal microswitch of the car [right red box], the right voltage level (HIGH, LOW on the green line) deviates significantly from the norm on the left.


After exchanging the two MS KV with new ones, these values were measured on the old ones:
Left: 2.49 kohms - 560 ohms => 1.282V in the non-actuated state on my EKG chart
Right 2.77 kohms - 560 ohms => 0.528V in the non-actuated state on the chart

I find it interesting and irritating, that this small resistance deviation causes such a large amount of signal distortion. So far I have no explanation for these trembling fluctuations.

But anyway, as recommended in my maintenance thread, these 2 microswitches should be replaced after 10 years to avoid exactly these surprising glitches. This Z4 was built in 2011.


E89: Retractable Hardtop (roof) Maintenance (and additional) tasks

Seems odd that such a response comes from such a minor variation in resistance…..especially since normally resistors aren’t usually highly qualified..

B21 said:

Seems odd that such a response comes from such a minor variation in resistance…..especially since normally resistors aren’t usually highly qualified..

Click to expand...

I agree. Maybe I'll understand it better in the near future with more tests on the input ports of the CTM.

RobbiZ4 said:

B21 said:

Seems odd that such a response comes from such a minor variation in resistance…..especially since normally resistors aren’t usually highly qualified..

Click to expand...

I agree. Maybe I'll understand it better in the near future with more tests on the input ports of the CTM.

Click to expand...

Robbie....you need to get your s**t together..otherwise I might have to help you!

Robbi! I'd guess your English is at least as good if not better than mine, but I'm pretty damn sure if we ever meet and you start talking about the E89 roof I won't have a clue what you're on about.
Keep up the good work.

enuff_zed said:

Robbi! I'd guess your English is at least as good if not better than mine, but I'm pretty damn sure if we ever meet and you start talking about the E89 roof I won't have a clue what you're on about.

Click to expand...

I'm pretty sure you'll understand everything.

Currently I'm developing a test tool to check the quality of the hall sensors based on an ESP32 microprocessor board:

The ESP32 is able to measure magnetic fields. With a fixed position on top of this chip, I can measure the quality of the internal magnet inside of the Z4 hall sensors.




Starting here:



We are running into more and more problems with aging hall sensors:

Push up