Precor Error Code 85 No Dynamic Brake Resistor Detected

Feb 13, 2022

Applies to TRM800.v2 treadmills

Issue symptoms

The Dynamic Brake Resistor is designed to absorb the excessive current produced by the drive motor running faster than it is being driven. When the motor control starts, it checks that the resistor is plugged in. If it does not detect the DBR(treadmill dynamic break resistor.), an Error 85 will be displayed. It will only be displayed briefly when power is applied to the MC(Motor controller, motor controller unit, or motor controller module: used on treadmills, contains the LPCA and motor controller functionality.). The most probable cause for this is the DBR not being plugged in, or it is open due to overheating or a broken cable.

Troubleshooting steps

1. Visually determine if the DBR is connected to the MC. Ensure the cable connector is securely fastened and locked to the MC connector.
2. Measure the DBR with a multimeter. It should read 100 ohms. If this is significantly higher than 100 ohms, replace the resistor.