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The PAS in the electric bikes is considered one of the most important technologies that have been added to the electric bicycle, which is also supported the presence of the most enjoyable type of motor, which is the mid-drive.
In the past, the electric bike worked with throttle only, however in my opinion, it was much less fun than what is the case now with the presence of the PAS
That is why you will find that the vast majority of e-bikes that have a mid-drive motor depend on the PAS, which gives great importance to it in the electric bike, especially since it is compulsory in many European countries and some American states
That is why in this post I will try to explain to you the most important problems that may occur in the PAS and how to solve them
However, before I start, you you should first know what the PAS consists of and how it works in the electric bike
Then we will move on to problems and solutions.
What is PAS & how it works on your electric bike?
The PAS is the pedal assist sensor, and it consists of four parts, a magnetic sensor, a wire, and a plug connected to the controller , as well as a magnetic disc.
The PAS works in the electric bike by fixing the magnet disc to the crank, so that it is exactly opposite to it the sensor.
When you use the pedal, the sensor senses the movement and sends a signal to the controller to allow the passage of an electric current from the battery to the motor
The amount of force coming out of the motor increases directly with the increase in the movement of the pedal and the rotation of the magnet disc.
Through the previous explanation, it becomes clear to you that there are 5 main parts that are used in order for the PAS to work. In the next part, we will explain the most important problems in these parts and how to solve them.
Why is my ebike PAS not working?
As a general rule, the PAS does not work well if there is a spacing between the magnetic disc and the sensor, or if the magnet disc is not installed on the crank well.
Of course, the previous two problems are the most well-known reasons why the PAS does not work well, but there are also some other reasons that we will discuss here
We will start the explanation from the easy issue to the most difficult issues.
1-Dirt or Mud on the Magnet disc.
The presence of dirt or mud on the magnet disc will reduce the sensitivity of the sensor to the movement of the magnet
The sign of this reason is the extreme delay in the degree’s response to the movement of your feet on the pedal
This problem can be solved by cleaning the magnet disc and the sensor well, if you find dirt on it, but make sure that cleaning the sensor is not done with water. Use a cotton with alcohol to clean it.
2-Gap between Sensor & Magnet disc.
One of the problems that cause the PAS to stop working is the presence of a large distance between the sensor and the magnet disc. If you have this problem, you will notice that the motor power is very weak compared to the speed of pedaling
In order to solve this problem, bring the sensor close to the disk, so that the distance does not exceed 1 cm, in order to get the best performance from the sensor.
Note: It is always preferable for the sensor to be close to the magnetic disk, but it should be taken into account that they are not sticking to each other.
On the other hand, some electric bike companies use high-quality sensors that allow you having a distance greater than 1 cm.
It is always preferable to refer to a seller to find out the correct distance in the event that your bike was in warranty or from a well-known brand.
3-Magnet is not gripping on the crank.
In many cases, the magnetic disc is inside the crank or is installed in a way that leads to movement on the crank, in this case you will notice that the bike works intermittently, in other words
You will get the same amount of power from the motor without any weakness, but intermittently
The solution to this problem is to fix the magnetic disc well on the crank using an adhesive or a nut.
4-Cut in wires.
One of the reasons for the PAS to stop working is the presence of a cut in the connecting wire from the controller to the sensor. In this case, I prefer to completely change the PAS to ensure the best performance. If you do not want to change, you can weld the wire again.
5-Sensor issue.
Also, one of the reasons that lead to the PAS stopping working is the presence of a problem in the sensor , and in this case you will not get any power from the motor with the continued use of the pedals.
The solution to this problem is by replacing the PAS, but in order to know that the sensor really has a problem, you need to measure it in millimeters using a 5 volt power source.
You can see how a 5 volt power supply works and how to test with a multimeter FROM HERE
6-Controller issue.
In a few cases, the PAS stop working is not due to a problem in the PAS, but the problem is in the controller, and if this problem occurs, the PAS alone does not stop working, but you will notice other parts stopped working also
The solution to this problem is to reset the controller, and if the problem is not solved, you have to test the controller and incase of errors you need to replace it.
You can check out the following two guides to learn how to do a test and a reset for your ebike controller.
3 Proven Techniques for Testing Ebike Controller at Home
Resetting Ebike Controller | Full Guide
7-Barke issue.
The brake function in the electric bike is to help stop the bike immediately, and the first step for the brake to do its work is to completely disconnect the electric current from the bike
So, if you notice the sudden stop of the PAS and all the previous problems are not present, you may try to disconnect the brake cable and try the PAS again.
If the PAS works again, the problem is with the brakes, not with the PAS
Conclusion.
There are 7 problems that can cause the PAS to stop working, and they are:
| Issue | Symptoms | FIX |
| Dirt or Mud on the Magnet disc | Extreme delay in the degree’s response to the movement of your feet on the pedal | Clean Magnet disc & sensor |
| Gap between Sensor & Magnet disc | Motor power is very weak compared to the speed of pedaling | Bring the sensor close to the disk, so that the distance does not exceed 1 cm |
| Magnet is not gripping on the crank | E-bike works intermittently, in other words You will get the same amount of power from the motor without any weakness, but intermittently | fix the magnetic disc well on the crank using an adhesive or a nut |
| Cut in wires | PAS will not function at all | Replace PAS or weld the wire |
| Sensor issue | No power from the motor while pedaling | Replace PAS |
| Controller issue | PAS & other parts won’t work | Reset or replace the controller |
| Brake issue | Sudden PAS stop | Disconnect the brake to test & then fix the brake issue |
