Alltrax NPX Troubleshooting: A Comprehensive Guide

Did your Alltrax NPX motor controller stop powering up suddenly without any warning? There could be a few problems that your Alltrax NPX motor controller runs into. 

Alltrax NPX non programmable motor controllers can stop powering up due to functional issues inside the controller. The LED lights of the controller can blink 3, 6, or 7 times because of different malfunctions. The cart run by the NPX controller can either lose speed control or run too slowly. 

Troubleshooting an Alltrax NPX motor controller is not that difficult if you know how to do it. In this article, you will find Alltrax NPX motor controller troubleshooting with their easy solutions.

Alltrax NPX Troubleshooting

What Are the Common Problems With Alltrax NPX?

When the Alltrax NPX faces problems, the LED blink codes will notify you about the possible issue.

You will be able to easily detect the problems by following this guide and fixing them.

Here are some of the most common problems an Alltrax NPX motor controller has:

  • Controller Not Powering Up 
  • LED Blinking Several Times
  • Lack of speed controls
  • The LED flashes continuously
  • Controller whistling or whining
  • Battery wires or motor getting too hot

Alltrax NPX Troubleshooting Guide With Easy Solutions

The Alltrax NPX controller’s red LED lights blink to display possible error codes in the controller.

Most of the problems can simply be solved with some little tweaks in the right place.

We will cover the symptoms, the causes, and the solutions to the most difficult problems so that you can fix the Alltrax NPX easily.

Problem 1: Controller Not Powering Up

When you switch on the controller, it doesn’t power up instantly and sometimes takes a lot of time to power up. This issue could be because of wiring problems inside the controller.

On the other hand, even after the controller powers up, the cart still doesn’t move due to internalized troubles. If your Alltrax NPX has this problem, the LED light will not turn into an amber color. 

Troubleshooting Controller Not Powering Up on Alltrax NPX

Check the wiring and the voltage of the Alltrax NPX when it is not powering up for some reason.

Usually, the reason for the controller not working is the voltage imbalance while on throttle. A few things can create controller issues on an Alltrax NPX, such as-

  • The voltage on the controller is not the same as the pack voltage at 0% throttle. 
  • Wiring to the pins 1-4 can be incorrect.
  • Voltage is not zero at full throttle.
  • The FR switch can be incorrectly connected.

How To Fix A Controller Not Powering Up On Alltrax NPX?

If the controller pops and smoke comes out when you power it on, disconnect the battery power immediately.

The controller can not be powered up anymore and needs a replacement in this case. Some of the other fixes for controller problems are-

  • Keep the throttle completely depressed and check for the pack voltage. 
  • On Controller B- and M-, check the current controller voltage.
  • Note that, at 0% throttle, the voltage should match the pack voltage. On the other hand, at 100% throttle, the voltage should be near zero.
  • If the controller doesn’t follow this and instead starts at half the pack voltage, replace the FR switch.
  • Get a new FR (Forward and Reverse switch) and connect it to the motor and controller properly.
  • Correct the wiring to pins 1-4 if they are improperly connected.

How Much Does It Cost To Fix A Controller Not Powering Up On Alltrax NPX?

In order to fix the controller, you will most likely need to replace the FR switch.

The FR switch replacement will only cost about $33. The forward and reverse handle with it will cost $21.

Problem 2: LED Blinking Several Times

The red LED indicates the controller’s program mode. There are particular LED blink codes while powering up that indicate different problems in the controller. 

Among several error codes, only the LED blinking 3, 6, and 7 times needs troubleshooting, and the rest will be fixed under proper temperature.The error blink codes are as follows:

  • LED blinks 1 times red- Throttle position sensor alarm
  • LED blinks 2 times red- Under Temperature Alarm
  • LED blinks 3 times red- High Pedal disable alarm
  • LED blinks 4 times red- Over Temperature Alarm 
  • LED blinks 5 times red- Unused Throttle Alarm
  • LED blinks 6 times red- Under-voltage Alarm
  • LED blinks 7 times red- Overvoltage Alarm

Troubleshooting LED Blinking Several Times on Alltrax NPX

Different problems lead to the LED lights blinking red. The amount of blinking refers to the causation of the errors in the Alltrax NPX controller. 

  • LED blinks 3 times because of high pedal disablement.  The throttle doesn’t go to zero during this power cycle.
  • Undervoltage causes the LED to blink 6 times.
  • The voltage is not around +/- 5V of the pack voltage.
  • Controller LED blinks 7 times due to overvoltage.

How To Fix LED Blinking Several Times On Alltrax NPX?

Fixing the LED light error codes Alltrax NPX involves correcting throttle and batteries.

If it is required, you will need to replace the battery or the solenoid accordingly. To fix the LED light blinking 3 times-

  • While powering up the controller, remove your foot from the throttle.
  • In ControllerPro, disable the HPD (High Pedal Disable) switch. 
  • In case the throttle is completely out of range, remove it and replace it with a new one.

To fix the LED light blinking 6 times-

  • Firstly, charge all batteries in case they are low on voltage.
  • Load test all of the batteries. If any of them are bad, replace them with new batteries.
  • If the voltage on the battery is +/-5V lower than the pack voltage, replace the solenoid.
  • Contant Alltrax Technical Support if the voltage is okay too.

To fix the LED light blinking 7 times-

  • Firstly, check the voltage between Control B+ and B-.
  • If the voltage on the battery is +/-5V higher than the pack voltage, check the wires connected to the solenoid.
  • In care any of the wires connecting to the solenoid are damaged or broken, replace or fix the wires accordingly.
  • Test if the chargers are overcharging the batteries. (<60VDC).
  • Check the serial number of the controller. If it is 3500 or below, contact Alltrax Technical Support.

How Much Does It Cost To Fix Led Blinking Several Times On Alltrax NPX?

  • If you are getting a new battery, it will cost you $800 to $1,500.
  • A set of new battery cables will cost around $20.
  • Replacing the throttle can cost you $140 to $270. 
  • Fixing any damaged wiring will only cost you about $23-$30.
  • If you are replacing the solenoid, a single solenoid can cost anywhere from $15 to $100.

Problem 3: Lack Of Speed Controls

The lack of speed controls on the Alltrax NPX can result in two kinds of events. They are-

  1. The cart driven by the controller runs too slowly.
  2. Controller only operates the cart at full speed without any changes.  

Either of these two can happen because of the lack of speed controls on the Alltrax NPX. Once the problem is created, the cart will face several problems while maintaining speed. 

Troubleshooting Lack of Speed Controls on Alltrax NPX

The main causes behind the lack of speed controls on the Alltrax NPX are faulty wiring and incorrect solenoid sizing.

Check the batteries, solenoid, and wiring to locate the specific reasons for this problem. The possible causes you will find are-

  • The insulation within the wiring can get hot.
  • Solenoid sizing and wiring are incorrect.
  • There is no voltage on pin 4.
  • Controllers M- and B- are wired incorrectly.
  • The controller setting of the Alltrax NPX doesn’t match the vehicle’s controller.

How To Fix The Lack Of Speed Controls On Alltrax NPX?

The solutions to the cart running too slowly or too fast differ a little from each other.

In most cases, correcting faulty wiring can solve all of your problems regarding this. To fix the cart running too slow-

  • Charge all the batteries fully.
  • According to the controller amperage, get the correct size of solenoid for the controller and do the right wiring.
  • Check if the wires are getting too hot due to insulation. If so, replace the damaged wires. 
  • When F/R is in reverse, make sure pin 4 has voltage on it.

To fix the cart only operating at full speed-

  • Check and connect the controllers M- and B- wires correctly.
  • Match the throttle setting of the controller to the throttle of the vehicle.
  • Charge the batteries of the controller.

How Much Does It Cost To Fix The Lack Of Speed Controls On Alltrax NPX?

  • A single solenoid can cost from $15 to $100, 
  • A pack of solenoids can cost anywhere from $50 to $300.
  • Mechanic’s cost: $120-$400
  • Parts/replacement cost: $15-$300
  • Fixing any damage will only cost you about $23-$30.


To avoid spending a hefty amount of money on repairs, you need to minimize the possible damage to your Alltrax NPX motor controller.

This troubleshooting guide will enable you to take better care of your controller by reminding you to check up on the wiring of the controller more often. 

Check up on your battery so that it always matches or is close to the pack voltage. The throttle settings of the controller should also be compatible with your vehicle at all times.

If the solutions and fixes are too difficult for you to comprehend, contact Alltrax at (541)476-3565 to avail themselves of their warranty service.

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