Home >> Jaguar >> 2012 >> XJ Base >> Repair and Diagnosis (Single Page) >> Quick Lookups >> DTC Index >> Diagnostic Trouble Code: Central Junction Box (CJB) -- XJ/X351 >> Diagnostic Trouble Code (DTC) Index DTC: Central Junction Box (CJB) >> Description And Operation >> Central Junction Box (CJB) >> DTC B12F4-12: Vehicle Speed Output - Circuit short to battery >> Possible Causes