Abstract: An electronic winch monitoring system for a winch having a fixed-ratio gearbox with input and output shafts, a winch drum connected to the output shaft, and an auxiliary brake connected to the output shaft activated by reducing the pressure in a brake release hydraulic circuit. The system comprises an input shaft speed sensor, an output shaft speed sensor, and an electronic control unit having a monitoring section and a brake control section. The monitoring section receives the speed signals, processes them to produce a calculated ratio of actual input to output shaft speeds, and produces a fault indication signal when the value of the difference between the calculated speed ratio and the fixed ratio exceeds a predetermined value. The brake control section, upon receiving the fault signal, reduces the hydraulic pressure in the brake circuit using a nonlinear pressure-time profile to engage the auxiliary brake and stop the winch drum.