CUSTOMER CONCERN ABS and traction-control warning lamps illuminate intermittently with DTC C1391 and no external brake-fluid leaks. CAUSE Accumulator pressure did not hold as specified, confirming an internal accumulator leak within the brake master-cylinder/skid-control actuator assembly. CORRECTION Remove and replace the brake master-cylinder assembly, perform the required brake-system bleed and calibrations, clear DTC C1391, and verify accumulator pressure and ABS/TRAC ope

CUSTOMER CONCERN The ABS and brake warning lights are on, DTC C1391 is stored, and the ABS pump cycles as accumulator pressure falls. CAUSE Accumulator-pressure testing confirmed internal leakage in the ABS brake actuator assembly. CORRECTION Remove and replace the failed ABS brake actuator assembly. Perform the required actuator initialization.