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Jeep Wrangler brake system diagnostic trouble codes (DTCs) C121C and C2200 are typically associated with the ABS hydraulic unit and pump motor control. C121C usually indicates an ABS pump motor control circuit malfunction, while C2200 often points to a faulty ABS relay or pump motor relay circuit. Common causes include a failed ABS pump motor, blown fuse or relay, damaged wheel-speed sensor wiring, corroded connector terminals, low battery voltage, or a failing ABS module. To diagnose, start by reading freeze-frame data with an OBD-II scan tool, then inspect the ABS fuse and relay. Check the wiring and connectors at the ABS module and pump, and test the wheel-speed sensors for correct resistance and signal output. Also verify battery voltage and ground integrity. Common repairs include replacing the ABS relay, repairing chafed or corroded wiring, cleaning connectors, or replacing the ABS hydraulic control unit/pump assembly. Always consult the factory service manual for your specific Wrangler model year, and perform a brake bleed and ABS initialization after component replacement.