Help! Giant Twist Express rs2 problem

rodyginv

Finding my (electric) wheels
Sep 28, 2023
5
0
Hello,

I have a problem with an old e-bike Giant Twist Express RS2.
After falling it doesn't assist anymore. It starts to assist just after turning on but stops in 1 second.
And I noticed strange sypthom: when I rotate the wheel, LED indicators of charge level are scrolling together with wheel rotation.
Could you suggest with troubleshooting?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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West Sx RH
The Giant twist is an older design bike and one is
assuming it is a simple cadence rotation system and not a Torque sensing affair.
A couple of things to check first off after an off or the bike fallingover.

Pretty sure Flecc or d8veh will be along soon as they both are very familiar with the GT bikes.

First the motor wire connection , carefully inspect the connection from the motor wheel for damage to the wire or connector. Any connector needs to be firmly pushed together if a two piece connection.

The other area is the BB /crank area.
One will have to show pics of the BB area, but suggest you look at the BB /crank wheel area for a PAS sensor and magnet if it is a cadence type system for damage.
Check the wire connection and also the sensor and disc alignment if fitted for damage.
A magnet disc should be undamaged and affixed firmly to the chain ring or to the BB axle , it should be approx. 1mm or less gap to the sensor head.
Like wise the sensor unit shoul dbe undamaged and firmly fixed in situ, as the disc rotates each magnet shoudl pass the sensor evenly around the axial rotation.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,161
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Telford
The only thing I can suggest is to unscrew the black cover thing that's on the left side of the motor and check that everything is OK in there. Maybe a wire got pulled in there. Also, check that the wires haven't been pulled at the control panel.

How did you pick the bike up? Was there a chance that you pulled a wire somewhere?
 

rodyginv

Finding my (electric) wheels
Sep 28, 2023
5
0
I have made a video of the problem:
Just after turning on the dysplay shows charge level.
But then it start showing the rotation of the wheel.

I have unscrewed everything and tested all wires. No broken or short cirquit wires found.

5442354424

I also opened the controller, and didn't find any visible problems:
54425

Could you suggest me what to else to check?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,461
8,346
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West Sx RH
There is no fault in the manual that mentions your LED issue , though it does mention a reset so one could try the reset.
Have you checked the batteries , try removing them and then reinserting them.
 

rodyginv

Finding my (electric) wheels
Sep 28, 2023
5
0
There is no fault in the manual that mentions your LED issue , though it does mention a reset so one could try the reset.
Have you checked the batteries , try removing them and then reinserting them.
Batteries are good. Voltage is 28.6. Of course, tried to remove and insert them back.

How to perform the reset ?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,461
8,346
61
West Sx RH
Just had a look at your pic of the front wheel and the fault is the damaged White cable from the controller to motor wheel connector. If you look carefully one can see in two places where the cable is damaged, in one place the cable is severly damaged and has been badly indented . One can expect internall smaller cable damage and likely broken wires and possibly shorting between them.

Repairing the cable will be messy and tricky , idealy the answer is a new wire loom with all the cables but spares might be an issue.
 
Last edited:

saneagle

Esteemed Pedelecer
Oct 10, 2010
5,161
2,494
Telford
It's very difficult to diagnose your problem from the photos. Instead, you should concentrate on what in the fall or pickup could have done the damage.

The battery has large mass and momentum, so that's the most likely thing to move. Look at the contacts and solder joints to them.

Next, is how you picked it up. Did you grab and/or pull any wires?

Last is any badly routed wires, like that white one. If a wire was getting bitten by something, did the jolt cause any to get bitten more or squished to the point of non-function?

You could also try putting a load on the battery to see if it can deliver any current. Maybe it now has an internal bad connection.
 

Cisco-man

Esteemed Pedelecer
Sep 27, 2023
252
55
Looking at the video, the leds makes me think the microprocessor in the controller is still running. You say the battery is well charged, but the display shows two pips up from empty. Makes me think that the controller is failing its startup routine, and showing some diagnostics?
 

Cisco-man

Esteemed Pedelecer
Sep 27, 2023
252
55
Didn’t wrap up my thinking well in my last post! My logic is that the battery is providing the power ok, the controller is running, and the leds are showing what looks like diagnostic information connected with wheel rotation. So Im thinking the controller doesn’t like the wheel for some reason such as broken wire, etc.
 

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