Strange PAS problem

davell

Pedelecer
Jun 6, 2017
142
58
Doncaster
Evening all, I'm looking for a little advice. I have a Volt pulse rear hub bike with standard PAS ring and thumb throttle. For 90% of the time all works fine. Every so often (maybe 2 or 3 times in a 30 mile ride) the PAS stops working after a short period of coasting (no pedalling). The throttle is also dead during this time. The LCD stays on.
Sometimes if I keep pedalling it will spring back into life. Sometimes not. I have noticed that a couple of revolutions backwards pedalling normally fixes things with both PAS and throttle working again.
I've done the basic checks on cable joint security etc but the problem persists. The PAS ring is consistently about 1mm from the sensor. I'd be grateful for any suggestions as to what the issue could be.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
16,585
6,461
58
West Sx RH
Could be a controller fault or conflict between the throttle and PAS, disconnect the throttle and use PAS only for a while. If no fault occurs you can rule out PAS, do the opposite and see what happens with throttle only and just pretend to pedal.
If individually no issue arises then the fault will be controller /pcb or internal wire issue.
 

davell

Pedelecer
Jun 6, 2017
142
58
Doncaster
I’ve done a bit more testing today. I’ve moved the pas disk a bit further from the sensor (about 2mm from 1). Just done a 20 mile test ride without issue. Can the distance of the sensor from the disk be too close? Maybe it’s just a coincidence!
 

davell

Pedelecer
Jun 6, 2017
142
58
Doncaster
Still having some intermittent issues with loss of power. Do pas sensors get ‘iffy’ or do they just fail completely. Adjusting the pas ring to sensor distance seems to alleviate the issue for a while.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,950
Basildon
If both throttle and PAS cut at the same time, there are two possible causes I can think of.
1. Faulty operation of a brake switch. That can be due to the rider riding with a finger on the brake or a sticky switch. In either case, disconnecting the brakes from the controller will solve it and show that it was the cause. If confirmed, connect one at a time to see which one is faulty, then inspect to see why.
2. A short on the 5v somewhere. That could be anywhere because the throttle, PAS, motor hall sensors and controller all work off the same 5v. The cause would be a damaged cable, faulty connector, pulled wire or something like that. The only way to confirm it would be to connect a separate Voltmeter between ground and any of the 5v wires to see if the 5v drops when you get the cut-outs. As your cut-outs seem to be linked to pedalling, I'd start by inspecting the cable that runs from the PAS to the controller. The short can also be caused by water in the throttle.
 

davell

Pedelecer
Jun 6, 2017
142
58
Doncaster
Thanks vfr400. Tried today with both brake sensors and throttle disconnected. Still getting the occasional power loss. Where would be a good place to monitor the 5v? All connectors are julet type. Will there be 5v at the brake sensor or throttle connections?
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,950
Basildon
Thanks vfr400. Tried today with both brake sensors and throttle disconnected. Still getting the occasional power loss. Where would be a good place to monitor the 5v? All connectors are julet type. Will there be 5v at the brake sensor or throttle connections?
If all connectors are sealed, it's not easy. You'd probably have to solder a wire to the controller's pcb and run it out.
 

esuark

Pedelecer
Jul 23, 2019
38
7
kent
I`m having similar problems did you ever resolve it davell. All`s OK so long as I don't stop pedaling or stop completely then to start the pas does not always kick in I can use throttle to initiate from zero and then join in with pas. (All new controller and pas`s 2 of). Sometimes even throttle does not start it but I hear a faint whirring noise, (being hard of hearing I must miss a lot of clues) I wait for that to stop and try again usually with success. I am now starting to think it`s the clutch. But with the bike on a stand the clutch seems fine and engages whilst turning wheel backwards, using pas and throttle always seems to work on the stand turning the wheel but there`s obviously no load. I`v taken the clutch out and it seems OK moves one way and locks the other. I`v done all davell`s done to no avail. Takes all the fun out of it.
 

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