Home >> Jaguar >> 2012 >> XKR 2D Convertible >> Repair and Diagnosis >> General Information >> DTC Index >> Diagnostic Trouble Code Index DTC: Headlamp Control Module A (HCM) -- XK/X150 >> Diagnostic Trouble Code Index DTC: Headlamp Control Module A (HCM) >> Description And Operation >> Headlamp Control Module [HCM] >> DTC U0121-86: Lost communication with Anti-lock Brake System (ABS) Control Module - Signal invalid >> Possible Causes