Gtech Ebike Sport

4Jake

Just Joined
Jun 26, 2022
1
0
Hi,
I am new to this forum so please excuse so any breaches of protocol.
I am trying to repair my neighbors Gtech sport bike. He uses it for his daily commute, whilst I am retired, so I have offered to try and sort it whilst he is at work.
I am a retired builder so more familiar with a hammer than a multi meter and with a dim memory of schoolboy physics (quite probably not the ideal qualifications).
The Bike. No power to the rear hub, or at least no action from the hub motor.
Battery appears to be good, showing 96% and outputting 41.5v. We have replaced the bottom bracket bearing & sensor assembly (with some damage to the sensor wires that required soldering).
The rear hub and pas sensor connectors look ok, no bent pins or obvious corrosion. The controller embedded in the battery carrier base has obviously endured water at some point since there is some corrosion in there. I thought I had found the problem seeing a rusted 4 wire plastic connector assembly loose within the controller space, but I suspect it is for functions like lights, brakes & display that the Gtech doesn't have. It appears to do nothing.
Testing the battery & harness off the bike is difficult. The battery shows error 24, I suspect because it is no longer connected to the hub. With the battery connected in this state, just to the harness, I get from the female hub motor connector:- Yellow phase 41.5v, Blue 0v and Green 6.6-8.1v. All the smaller sockets give 3.2v except for one that starts at 11v and descends. I am tempted to put down the meter and reach for my hammer.
That was the easy connector, the pas has tiny pin & pinholes, 6 although there are only 3 wires on the pas sensor. From trawling the boards I know the wires should be ground, signal & power(circa 5v), but I can only probe for continuity. Having established the three wires that are not open circuit, how do I discriminate which wire is which?
If anyone has any kind of labeled diagram of the pas sensor connector I would be very grateful. Any advice would be welcome, apart from 'take it to a bike shop'. My neighbor cannot afford expensive repairs.

Thank you for your time.
Jake Neal
 

stargazer30

Pedelecer
Sep 29, 2020
44
21
Hi, go on Facebook and join gtech owners group, your best bet is to find a local owner who can help, maybe try their battery etc..

The gtech system as you know is very simple. It’s either the battery, controller, bottom bracket sensor or the the hub motor. There’s nothing else to go wrong. Generally speaking the most common fail point are the batteries, especially the v2 square button ones. The hub motors very rarely go but if it’s done starship miles it’s worth a look. The gtech motor is a bafang hub, so you can connect up any regular hub motor like a yose 350w and test if that’s the problem. You already replaced the bottom bracket speed sensor so my money would be on the controller base or the battery.