Home › Jaguar › 2015 › XKR-S 2D Convertible › Repair and Diagnosis › Quick Lookups › DTC Index › Diagnostic Trouble Code Index DTC: Transmission Control Module (TCM) -- XK/X150 › Diagnostic Trouble Code Index DTC: Transmission Control Module (TCM) › Description And Operation › Transmission Control Module [TCM] › DTC P0826-81: Up and Down Switch Circuit - Invalid serial data received › Possible Causes