Help! Viking Freedom 700c fault

[davlaw2000]

Hi all my bike has developed a fault and I was hoping you could advise on how to get to the root cause. It's a Viking Freedom 700c. When I switch it on, the display powers up as usual, but the motor isn't working. I have checked the simple stuff ie looking for loose connections and broken wires. I noticed that there is a red flashing light shining through a hole in the motor control unit, where one of the cables goes in. It is a steady single pulse. Could this indicate a fault in the control unit? It is 6 years old and nothing lasts forever so I'm happy to get a replacement if that is what I have to do.
Any advice on diagnosis please?
Dave

 

[saneagle]

The red flashing LED is normal. We need a lot more info to help you solve your problem. What's all the other stuff? Please show the motor, the wires or pins in the motor connector, and tell us how it started. Motors don't just stop for no reason.

 

[davlaw2000]

The red flashing LED is normal. We need a lot more info to help you solve your problem. What's all the other stuff? Please show the motor, the wires or pins in the motor connector, and tell us how it started. Motors don't just stop for no reason.

Ok well it simply worked one day and didn't work the next. It's not been ridden in the rain so it can't be water damage. I'll take further photos and will add them ASAP. Thanks.

 

[davlaw2000]

More photos as requested. I checked all connections. Clean and tight. I also cleaned the rotating disc at the crank but it looks magnetic rather than optical. I noticed there are switches on both brake levers too. Again clean and no obvious damage. The brown marks on the cables are dirt of some kind - definitely not burns.

 

[Nealh]

Show us the display, does it have walk assist. If so activate walk assist to check if the motor works.
Depress the down button and after a couple of secs the motor should work at 6km/h, if so then either the motor connection isn't all the way pushed home or the PAS sensor/magnet disc may have been knocked out of alignment.

Has the bike been knocked or fallen over ?

 

[saneagle]

If I were to take a wild guess, I'm going to go for the pedal sensor behind the chainwheel. The magnet disc needs to be an even 1mm from the sensor. Have a look whether everything is OK there, that the disc turns with the pedals and the connector is clean.

After that, you need to measure the battery voltage after fully charging it.

EBikes cannot stop working for no reason. Think back about what happened to it between when it was working and when it wasn't.

 

[davlaw2000]

If I were to take a wild guess, I'm going to go for the pedal sensor behind the chainwheel. The magnet disc needs to be an even 1mm from the sensor. Have a look whether everything is OK there, that the disc turns with the pedals and the connector is clean.

After that, you need to measure the battery voltage after fully charging it.

Ok will do. Thanks!

 

[Nealh]

Dave has walk assist so if that works then the field can be narrowed down instantly to the PAS as the likely fault.

 

[RogerA]

Can you disconnect the brake sensors? If so, do that and see if it works. If it does then reconnect each one individually and identify which is faulty. You could then look for a replacement but personally I wouldn't bother. Just use one brake sensor. It's only used to cut power to the motor when you operate the lever.

 

[davlaw2000]

There is no walk assist as far as I'm aware. I have checked the crank sensor and the two brake sensors. All appears clean and operating normally. I will try disconnecting the brake sensors later today. The battery has a healthy voltage (41 fully charged). I'm tempted to test the motor but I see six pins on the connector and I don't know which two are power.

 

[davlaw2000]

Can you disconnect the brake sensors? If so, do that and see if it works. If it does then reconnect each one individually and identify which is faulty. You could then look for a replacement but personally I wouldn't bother. Just use one brake sensor. It's only used to cut power to the motor when you operate the lever.

I disconnected both brake sensors but that made no difference. Looks to me like the motor or the control unit but I guess it could still be the crank sensor. The speedometer still works when I ride.

 

[saneagle]

There is no walk assist as far as I'm aware. I have checked the crank sensor and the two brake sensors. All appears clean and operating normally. I will try disconnecting the brake sensors later today. The battery has a healthy voltage (41 fully charged). I'm tempted to test the motor but I see six pins on the connector and I don't know which two are power.

It's a three phase sensorless motor with a speed sensor. You can't test it bu putting a battery to it. The three bigger pins are the three phase wires and the three thinner ones are for the speed sensor. It's very unlikely there's anything wrong with the motor. They're very robust and even if one phase were burnt, it would still hum or twitch.

One problem you can get is a damaged cable, but the damage would have to be pretty substantial to stop a sensorless motor from working, so you should be able to see it. Even with that, the motor shouls still hum, tic or twitch when you appy power. Take of the chain to test for that.

If you want to waste time testing your motor, you set your meter to the lowest volts A/C setting, connect the probes to any pair of phase wires, then spin the wheel BACKWARDS. It should generate a few volts. Repeat for all three pairs.

There is no walk assist as far as I'm aware.

Do you mean that the walk assist doesn't work because your KD58C does have it. You hold down the "-" button for more than two seconds.

 

[davlaw2000]

It's a three phase sensorless motor with a speed sensor. You can't test it bu putting a battery to it. The three bigger pins are the three phase wires and the three thinner ones are for the speed sensor. It's very unlikely there's anything wrong with the motor. They're very robust and even if one phase were burnt, it would still hum or twitch.

One problem you can get is a damaged cable, but the damage would have to be pretty substantial to stop a sensorless motor from working, so you should be able to see it. Even with that, the motor shouls still hum, tic or twitch when you appy power. Take of the chain to test for that.

If you want to waste time testing your motor, you set your meter to the lowest volts A/C setting, connect the probes to any pair of phase wires, then spin the wheel BACKWARDS. It should generate a few volts. Repeat for all three pairs.

Do you mean that the walk assist doesn't work because your KD58C does have it. You hold down the "-" button for more than two seconds.

I was unaware of the walk assist as it came with no manual. I'll try it later. I put the bike up on one of those tripod things. No humming or twitching when I pedal. If the motor is bullet proof we are down to the crank sensor or the control unit then...

 

[saneagle]

No humming or twitching when I pedal.

You wouldn't see, hear or feel it if the chain is on.

 

[Nealh]

KD58C does have the walk assist mode , try it first to see if the motor runs. Depress the minus/down button for a few secs. If it works it will then reduce any fault to be nothing more then a PAS alignment issue or it's wiring in most cases.

 

[davlaw2000]

The walk assist mode does work. So I think that narrows things down to wiring, the sensor on the crank, or (perhaps less likely) the control module. I'll start with the crank sensor - remove, clean, check wiring and replace if there is nothing obvious. I wonder whether it's a generic part....

 

[davlaw2000]

I checked the crank sensor and found nothing obvious so I decided to check where the cable goes into the control box. I found one of the wires (white) linked to a connector but the connector seems to have broken away from the main board. Logic tells me that a connector like that should be fixed to the board. I have posted a couple of pictures but I see they aren't very clear so I'll take a few more when I can. Meanwhile any suggestions?

 

[davlaw2000]

A clearer photo. Any idea where that white wire goes?

 

[Nealh]

One can see that it sits in position marked TB &TA , the White wire is TA/CON5.

 

[davlaw2000]

One can see that it sits in position marked TB &TA , the White wire is TA/CON5.

Great, thanks. A simple soldering job for this afternoon then!