help please - new KT36/48svprm-sjt02L controller w LED 880 display

dtbaker61

New Member
trying to help a buddy get his eBike back up and running... it is about 6 yr old, and just 'stopped working'. The display he had was PAS only, and I noticed the PAS sensor light was not blinking when pedal rotated, so I tried replacing just PAS sensor first. no go. So, I ordered new KT controller and matching LED display (PAS only, no throttle). The new controller came with lots more connectors that the old one, and different ends.... So I cut off the ones I needed to and spliced to match.

I now have everything looking good with PAS blinking when pedaling, but the motor never kicks in.

The other odd thing is that when I connect the motor sensor 5 wire to the controller 5 wire, the display shows low battery voltage and PAS sensor light dims. I disconnect, and battery shows full. Reading other threads, it sounds like the big motor phase wire colors may or may not match the new KT phase wires..... Would this POSSIBLY explain the behavior and the motor not 'kicking in' even though everything else is ok? If so, how do I determine the correct matching of the motor phase wires? Would I need to change the order of the 5pin sense wires as well?

or.... is it more likely that the wire harness itself is bad? I see only 3 fat pins in the motor-side connector, I dont see anything for the 5 sense wires at all coming from the motor ?!

so.... the question MAY be whether or not a KT controller that has both 3-pin phased power, and a 6-pin sensor connector will work with a motor that doesn't seem to have any 'live' sensor wires? The old controller did not have a 6-pin sensor connection at all... so are there two basic types of the controllers and NOT interchangable?
 
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harryS

Well-Known Member
The other odd thing is that when I connect the motor sensor 5 wire to the controller 5 wire, the display shows low battery voltage and PAS sensor light dims. I disconnect, and battery shows full. Reading other threads, it sounds like the big motor phase wire colors may or may not match the new KT phase wires..... Would this POSSIBLY explain the behavior and the motor not 'kicking in' even though everything else is ok? If so, how do I determine the correct matching of the motor phase wires? Would I need to change the order of the 5pin sense wires as well?

or.... is it more likely that the wire harness itself is bad? I see only 3 fat pins in the motor-side connector, I dont see anything for the 5 sense wires at all coming from the motor ?!

so.... the question MAY be whether or not a KT controller that has both 3-pin phased power, and a 6-pin sensor connector will work with a motor that doesn't seem to have any 'live' sensor wires? The old controller did not have a 6-pin sensor connection at all... so are there two basic types of the controllers and NOT interchangable?
Trying to understand. FIrst paragraph says the motor's five pin connector loads down the controller. Second paragraph says the motor only has a three pin cable. You'll have to clarify this inconsistency.

This is what comes out of a lot of motors. Three bullets, yellow, green, blue and a 6 pin connector, sometimes with five wires and sometimes six wires: red, black (+/- 5 volt), white (speed if present), and yellow, blue, green (position sensor outputs).

Personally, I've never gone wrong hooking by color, but maybe I'm dealing with mainstream motors. If your motor has only three thick wires, then it's a sensorless motor and you need a sensorless controller.

motor cable.jpg
 

dtbaker61

New Member
When I ordered the new controller I was fooled by the harness end that was in the controller box, which has 3 fat phase wires, and had a 5-pin connector with a single white. Turns out this harness was a motor cable extender, and when I look at the hub motor cable tail going to the hub, there are just the 3 fat pins, no sensor wire pins in sight inside the connection.

from your last sentance, I can infer that there are two distinctly different types of KT controllers; those having the 6-pin sensor connector, and those without.... which is what I guess I need to order.... unless there is some easy way to fake out the sensored controller to work without motor sensor data?
 

harryS

Well-Known Member
You're correct. You have a sensorless motor and need a sensorless controller. This KT unit is sensorless. Generally, the higher power KT square wave controllers are sensorless.


You can run a motor with sensors on a sensorless controller, but you need a sensorless controller to run a sensorless motor.

I believe I bought this one in 2016. Using it on a sensored motor.

 

dtbaker61

New Member
You're correct. You have a sensorless motor and need a sensorless controller. This KT unit is sensorless. Generally, the higher power KT square wave controllers are sensorless.


You can run a motor with sensors on a sensorless controller, but you need a sensorless controller to run a sensorless motor.

I believe I bought this one in 2016. Using it on a sensored motor.

dang..... I guess I'll buy another controller and try again! fortunately only about $50. thanks Harry!
 

harryS

Well-Known Member
Now the only thing I wonder about is why your extension cable loaded down the new controller, given there's nothing on the other end.
 

dtbaker61

New Member
Now the only thing I wonder about is why your extension cable loaded down the new controller, given there's nothing on the other end.
yeah..... my concern is *maybe* that cable has a fault or short inside it for the 6 motor sense wires.... but that would be irrelevant if I don't have motor sense connector on a sensorless controller.

When I opened the connector up, there was a fair amount of 'something' liquid in there; I asked the owner, and he sprayed wd-40 in it when he was having problems initially. I am thinking there is a chance that the liquid, whatever it is, may have enabled a partial short between the 12v sensor wires from the controller.... which showed as 'low battery' on the display. fortunately, nothing burst into flames.... but I certainly will see if I can get that liquid out, whatever it is, before re-connecting to a new controller!
 

dtbaker61

New Member
ok, more information, and more puzzlement now after cleanout the Julet connector with 'mass airflow sensor' spray which evaps super fast. I put a good light on the connection, and took off my readers so I could get a REALLY close look with my myopic eyes, and noticed there ARE motor sense contacts on the motor side of the connector!

However, re-connecting everything, the LED display for battery % drops from full to blinking 'low' as soon as I connect the motor sense connector. I guess it *could* be a short in one of the sensor wires, either in the hub motor pigtail, or the cable extension, or in my connector splices... but I was pretty careful with colors.

I think I have the following options to try next:
A. replace Julet harness section between motor and controller hoping there is an internal short
B. replace controller with a sensorless controller (which was what the original was)
 

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