How to fix no power and exclamation mark error on an e-bike [ADO D30C]

I am currently in the middle of reviewing the new ADO D30C electric bike. I really like the bike, and it works well for both trail use and as a hybrid/town bike for commuting and leisure.

However, when my sample arrived, I had some problems with the electric motor engaging and an exclamation mark showing on the digital display.

Because this was a review sample shipped from the factory, I didn’t have the same level of support a retail bike would get and had to try and communicate with the Chinese engineers. As helpful as they tried to be, there was a bit of a language barrier.

With a bit of Googling and the help of the engineers, I was able to work out what the problem was and how to fix it. This problem can happen with most/all e-bikes. While my fix won’t work for all people or even most people, it may help point you in the right  

Exlamation Mark Error

My main problem with the support I received was that it was never explained to me what the error was, so it felt like I was just doing random things to the bike.

A bit of Googling revealed the exclamation mark pops up when you apply the breaks. This is to indicate that the power to the motor is cut off due to the brakes.

Once I realised this, everything made a lot more sense.

Fixing the exclamation mark error  

If the exclamation mark is permanently on, it means the bike thinks the brakes are applied.

None of these worked for me but possible solutions:

• Make sure the level is fully released, push it out to make sure it is not stuck
• Check the magnet has not slid up on the brake lever
• Check all the connections around the brake levers and make sure nothing is loose
• The engineers suggest inserting a piece of metal into the hole where the brake lever is. This is one of the things that made me quite confused about what I was doing and why

None of those fixes worked for me. Instead, I removed the battery and opened up the bike to where all the wires are connected and checked all the connections.

With the help of the engineers and a lot of trial and error, I found the cable that causes the exclamation mark. Unplugging it removed it, plugging it back in caused the problem again.

I also found another cable with the same colours that were not plugged in, so I tried swapping them over. I sloppily reattached the battery and cycled around my garden, and everything magically worked. I was concerned that I had disabled some safety features but applying the breaks brought up the exclamation mark and switched off the motor, as it should.

With my bike, the cable in question was the yellow and black cable which had a black push connector with two pins inside. There were three of these cables, two of them connected and one disconnected and tied up.

Unfortunately, opening up the bike, messing around with the cables and trying to get everything back in was quite difficult and frustrating. The cables are tightly packed, and getting everything packed in far enough that I could screw down the battery connector took quite a long time.

Also, when I pulled the wires out, the key and lock mechanism popped out. Without this back in place, the battery wouldn’t click into place properly.