Home >> Land Rover >> 2021 >> Defender 90 X-Dynamic S >> Repair and Diagnosis >> Quick Lookups >> Common Specs & Procedures >> Diagnostic Trouble Code Index DTC: Cruise Control Module -- Defender/L663 >> Diagnostic Trouble Code Index - DTC: Cruise Control Module (G2818898) >> Description And Operation >> Cruise Control Module (CCM) >> DTC C0078-61: Tire Diameter - Signal calculation failure >> Possible Causes