Hardtop Slow Warning over 20mph

Street · Post by **Street** » Tue Nov 16, 2021 6:22 pm

When I put the hardtop on the z4 I get a "slow" warning alert when I drive over 20mph.
The warning lights flash in slow time (but only on the interior dash). The external hazards aren't flashing.
The sat nav screen also flashes "SLOW" as well.

I've taken the fixing posts off the hardtop and can recreate the issue by putting them on and taking them off. That just saves struggling with the hardtop every time.

I dont think there is any hall sensor in the front latches. Perhaps someone could confirm that for me?
I'm getting no related codes on ISTA+

The car has a Gap-Tech for the softop that is working fine. Just for reference in case it could be part of the issue.

Jas- USA · Post by **Jas- USA** » Tue Nov 16, 2021 10:07 pm

Maybe your cross posting this problem to another z4 Forum, using another user name or another fellow has the exact same problem with a hardtop installed & then the flashers going off above 20. https://www.zpost.com/forums/showthread.php?t=1825280 Please see last posting.

Street · Post by **Street** » Wed Nov 17, 2021 12:14 am

Its me Jas, cheers for looking. Thats the only reference I can find on the web of this issue.

Jas- USA · Post by **Jas- USA** » Wed Nov 17, 2021 1:10 am

Really sorry to hear about this issue. I actually wouldn't know where to start with this, like where is the common link between the hardtop wiring and the flashers? Is there a specific fuse for only the flashers ( which won't effect the turn signals) and if you pulled it maybe you'd be able to use the hardtop until next spring when you go back to the soft top and then put the fuse back in. No this isn't a fix, but If it works you'll have the hardtop for the winter...but no flashers until spring.

Street · Post by **Street** » Sun Nov 21, 2021 6:41 pm

Fixed in case anyone searches in the future.

My issue was a ‘smarttop’ from modsforcars. It’s a one touch roof aftermarket gadget. It’s not a compatibility issue as it was fine previously but removing it has solved the issue.

The 20mph warning and hazards can be replicated by driving with the softtop unlatched. It’s obviously triggered by a hall sensor of the boot latch normally.
However with the hardtop connected it was sending it wobbly. Using ISTA the car knew all the softtop latches are locked. So why it acted the way it did is a mystery.

I can only assume unplugging the CVM to remove the smarttop gadget has reset it somehow. Maybe in the summer I’ll plug it in again and see if it fails again.

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