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Here in our shop we test speed control modules on our test bench by plugging a good motor and throttle into them, bridging their power switch connector with a jumper wire, and wiring them to our variable DC power supply and setting it to the correct Voltage for the controller. However this requires owning equipment that most people do not already have.

To test a control module without a variable DC power supply and a spare working motor and throttle, all of the parts that plug into the controller will need to be tested. If the test results show that all of the other parts are good then the controller can be deemed faulty by the process of elimination.

Before performing any tests recharge the battery pack until the charger lights indicate that it is fully charged if the battery pack has not already been recharged in the last 30 days.

The first test I would perform is to unplug the brake switch from the controller and see if it runs then. Brake switches sometimes fail and lock into the on position which tells the controller to turn off the motor. Some newer scooters have normally on brake switches so the next step is to bridge the controller's brake switch connector terminals together to simulate a normally on brake switch. If the motor does not run with the brake switch unplugged from the controller, or with the controller's brake switch leads shorted together, then the brake switch can be temporarily eliminated as being the problem. Next the brake switch should be tested for continuity in both its on and off positions to verify that it is good so that it can be fully eliminated as being faulty.

The next step is to unplug the power connector from the controller, turn the vehicle's power switch on, and see if there is any Voltage reaching the controller. If there is no Voltage reaching the controller, and the battery pack has Voltage in it, then either the power switch, fuse or circuit breaker, or wiring harness is faulty.

The next step is to test the Voltage of the battery pack. It needs to have a certain minimum Voltage in order to run the motor. The low Voltage cutoff levels for most controllers are:

• 10 Volts for a 12 Volt battery or battery pack.
  
• 20.5 Volts for a 24 Volt battery pack.
• 31 Volts for a 36 Volt battery pack.
• 42 Volts for a 48 Volt battery pack.
• 53 Volts for a 60 Volt battery pack.
  

If the battery pack is under the low Voltage cutoff level then it will not provide enough Voltage to test the controller, and will need to be replaced before it can be used for testing.

If the battery pack is above the low Voltage cutoff level then the next test to perform is a battery pack load test. To perform this test read the Voltage of the battery pack with the vehicle's power switch off, and then again with the power switch on and throttle fully engaged. If during this test the battery pack's Voltage drops under the low Voltage cutoff level then it has failed the load test and needs to be replaced.

If the battery pack, power switch, fuse or circuit breaker, and wiring harness test good then the next step is to test the motor. To test the motor, assuming it is a brushed motor with two wires, unplug it from the controller. Then using jumper wires momentarily connect the motor leads to one of the batteries in the battery pack, or to a spare 12 Volt battery or 12 Volt automotive battery charger if you have one. If the motor spins while connected to a power source then it works, and of course if it does not spin then it is faulty. The reason I recommend to test it at 12 Volts instead of 24, 36, 48, or 60 Volts is because at these higher Voltages the test leads might spark heavily when connected to the power source and could weld themselves to the power sources lead.

If the battery pack, power switch, fuse or circuit breaker, wiring harness, and motor test good then the next step is to test the throttle. To test the throttle follow the instruction on this page: http://www.electricscooterparts.com/throttletestingguide.html

If all of the parts connected to the controller test good then it can be safely assumed that the controller is faulty.

These test procedures could of course be performed in a different order than as described above, this order of testing represents the sequence that we would test the parts in. Others may prefer to test the parts in a different order than we do.

Please let us know if you have any questions.