Pull-Up Resistor Failure
The most common cause of this issue is the "pull up" resistor for the encoder. This is located in a gray plug on the power harness near the controller. The resistor assembly plugs into the harness. Many people do not know that the resistor assembly exists or what its function is.. What it does to boost the encoder signal going to the motor controller. If the resistor fails to open or shorts, it messes up the encoder signal to the controller, which then defaults to a slower speed. On LSV’s, this is easily noticeable because the default speed is less than what the normal programming would allow. On BC3’s, which have the HD motor with the encoder, and a high/low switch, this can be tricky because the default speed may match the forward low speed. Customers may report this as the vehicle being stuck in forward low.
The resistor should measure around 10k ohms +/- 10%. In practice, most are measured at 9.8k.