The Eaton Lightning Transmission Control Unit (TCU) is a foundational component in early automated manual transmission systems, utilizing a combination of electronics and pneumatics to actuate the splitter and range cylinders to automatically shift gears when the specific conditions are met. As a legacy system, the Lightning TCU remains a critical part for fleets still operating older Eaton Lightning equipped trucks. Weller Truck Parts offers quality-tested used OEM Lightning TCUs that provide a cost-effective solution for maintaining legacy systems. Each unit is inspected and verified for functionality to ensure dependable performance. Backed by Weller’s industry-leading warranty and supported by expert tech support and responsive customer service, you can count on Weller to help keep your fleet moving. Whether you're replacing a failed module or extending the life of your existing equipment, Weller delivers trusted parts with unmatched support.