PAS sensor not working

Get all your technical information about electric bikes here.
Post Reply
platyase   10 µW

10 µW
Posts: 5
Joined: Dec 20 2019 11:21am

PAS sensor not working

Post by platyase » Dec 20 2019 11:47am

I'm putting together my first e-bike with parts purchased online, but I'm having trouble getting the PAS sensor to work. The parts I'm using:

KT-LCD8 LCD
KT36/48ZWSRM-ffF01 motor controller
MXUS XF07 350W hub motor
KT-D12FL split ring PAS sensor
EGO 52V battery (I have a few of these from my yard tools)

The system seems to work fine with the throttle. When I turn the throttle, the LCD indicates that the throttle is on and the motor spins. When I turn the pedals, the red LED on the PAS sensor lights up, but there is no change on the LCD and the motor does not turn. The red LED on the PAS sensor only lights up when I turn the pedal forwards and doesn't turn on when I turn the pedal backwards, so I believe it is installed correctly. The LCD and motor do not respond whether I turn the pedal forwards or backwards.

Since things work with the throttle, it seems that the problem is somewhere between the PAS sensor, controller, or LCD.

From searching the forums, it seems that this can occur if the LCD parameters are not set correctly. I've set C1=6, which should be okay for a 12 magnet PAS sensor installed on the left side. I've attached a photo of the other parameters in case anything else might be set incorrectly.

I have juliet connectors, so it's not easy for me to check whether the connections are okay. The PAS sensor is at least getting power from the controller since the red LED lights up when pedaling. If I open up the controller box, then that might give me some access to check signals on the wires? Anything in particular I should be looking for?

Thanks for any suggestions!

Image

AHicks   100 W

100 W
Posts: 296
Joined: Jul 24 2018 10:53am

Re: PAS sensor not working

Post by AHicks » Dec 20 2019 12:43pm

You have something going on, but not sure what. It's not likely just the settings. That red light should come on and stay on regardless if you are pedaling or not.

platyase   10 µW

10 µW
Posts: 5
Joined: Dec 20 2019 11:21am

Re: PAS sensor not working

Post by platyase » Dec 20 2019 1:07pm

AHicks wrote:
Dec 20 2019 12:43pm
You have something going on, but not sure what. It's not likely just the settings. That red light should come on and stay on regardless if you are pedaling or not.
Are you saying that the red light on the PAS sensor should turn on when the controller is on, regardless of whether I am pedaling? I'm wondering if mine works differently? It turns on when I turn the pedal forwards but stays off if the I turn the pedal backwards. There is no light if I don't turn the pedals. Also no light if I turn the pedal forwards but the PAS cable is unplugged (so it's not somehow generating its own power).

goatman   100 kW

100 kW
Posts: 1405
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: PAS sensor not working

Post by goatman » Dec 20 2019 3:21pm

split ring 12 pole disc, have you tried flipping the disc so the other side is facing the the red light sensor, I had that problem once

goatman   100 kW

100 kW
Posts: 1405
Joined: Jun 23 2019 6:50pm
Location: Surrey, B.C.

Re: PAS sensor not working

Post by goatman » Dec 20 2019 3:41pm

also the sensor with the red light. when I was having trouble with mine I had youtubed it and if your sensor is at a certain angle it wont work but you move it a couple degrees this way or that way it will work, I had that problem once also

platyase   10 µW

10 µW
Posts: 5
Joined: Dec 20 2019 11:21am

Re: PAS sensor not working

Post by platyase » Dec 20 2019 3:58pm

Thanks, Goatman. I had thought that the sensor was sensing correctly since the red LED on the sensor only light up when the pedals were turning forward. But I'll try your suggestions in case the red LED isn't doing what I thought it does, as AHicks suggested that it should always be on. If you have the sensor with the red light, is it always on or does it only turn on when the pedal is turning forwards?

AHicks   100 W

100 W
Posts: 296
Joined: Jul 24 2018 10:53am

Re: PAS sensor not working

Post by AHicks » Dec 20 2019 5:20pm

I found that the number of magnets I used when setting mine up didn't make much difference on anything. Also, there were 2 sets of numbers, a low set and a higher set. If one of the low set won't work, try one of the higher set numbers. I believe one set is for the magnet ring on one side of the crank, the other the opposite side.

Sensor distance from the magnets may also be a factor.

aroundqube   1 kW

1 kW
Posts: 473
Joined: Mar 12 2012 9:58pm

Re: PAS sensor not working

Post by aroundqube » Dec 20 2019 7:12pm

In general , red light on indicates power on . One side of the magnet disc has the letter " A " for active. The active side faces the sensor. Red light blinking while turning crank forward, every time magnet passes sensor, indicates sensor is working. Appears to be several versions of the KT-LCD8 . If this one is yours : http://www.szktdz.com/upload/file/20191 ... _78856.pdf then C1=6 with a KT 12 magnet ring, it is looking for a reverse waveform.

docw009   100 kW

100 kW
Posts: 1279
Joined: Aug 02 2015 7:43am
Location: Chicago area suburbs.

Re: PAS sensor not working

Post by docw009 » Dec 21 2019 12:38am

Just for the heck of it, try C4 = 0 or C4 = 3. Those are the two settings I use, the latter allows throttle at any time, and the former is PAS only. Never tried C4=2 and barely understand some of these C parameters. I just use what works,

platyase   10 µW

10 µW
Posts: 5
Joined: Dec 20 2019 11:21am

Re: PAS sensor not working

Post by platyase » Dec 21 2019 3:02am

Thanks for all of your help! I was able to get hold of another PAS sensor (of the same model), and this one works fine. So I guess my first PAS sensor was defective. For reference, on this sensor, the red light only turns on when pedaling forward. It does not turn on when the controller is powered on but the pedal is not moving or moving backwards. It sounds like this is a change from other PAS sensors.

User avatar
amberwolf   100 GW

100 GW
Posts: 29844
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: PAS sensor not working

Post by amberwolf » Dec 21 2019 10:52pm

the few pas sensors i have here tht have a light on htem only light when magnets pass them, and only if in the correct direction.

User avatar
wturber   10 MW

10 MW
Posts: 2128
Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
Contact:

Re: PAS sensor not working

Post by wturber » Dec 22 2019 9:54pm

I damaged a PAS sensor when I pressed it onto my crank spindle and cracked it. The result was that the internal mechanism was slipping on the crank spindle and not turning. You may want to inspect yours for similar or some other kind of damage. In my case, the PAS worked fine when it wasn't attached to the axle and I spun it by hand.

viewtopic.php?f=2&t=90369#p1332443
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

platyase   10 µW

10 µW
Posts: 5
Joined: Dec 20 2019 11:21am

Re: PAS sensor not working

Post by platyase » Dec 23 2019 1:02am

Thanks for the suggestion. As I mentioned above, the problem was solved by using another of the same model sensor. So the first one was defective.

On the defective one, the red light lit up when the pedal was spun forward, so it was sensing correctly but somehow not sending the signal to the controller.

Post Reply