CUSTOMER CONCERN DTC C1391 is stored and the ABS actuator pump cycles repeatedly while a hissing sound comes from the actuator. CAUSE Accumulator pressure repeatedly fell from about 3.8 volts to 3.2 volts, causing the pump to restart. The actuator leaked internally past its solenoids and could not hold brake pressure. CORRECTION Remove and replace the ABS actuator assembly, perform the required resets and calibration, clear DTC C1391, and verify accumulator pressure remains s

CUSTOMER CONCERN Customer reports multiple ABS warning lights illuminated with DTC C1391. The pump and accumulator assembly had been replaced previously, but the warning lights and code returned after approximately 200 miles. CAUSE Diagnosis confirmed an internal leak and failure in the ABS actuator and electronic control unit. The accumulator pressure did not remain within specification, causing C1391 to reset after the separate pump and accumulator repair. CORRECTION Remove