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Transmission Control System (Smoother) 7A-159 U0100, U0121 (Flash Code 42, 68) Circuit Description • The ignition switch is ON. Condition for Setting the DTC • The TCM detects that the CAN Bus OFF Status. U0121 • The TCM detects that the CAN Bus. Action Taken When the DTC Sets • The TCM illuminates the transmission warning lamp when the diagnostic runs and fails. (U0100) • The TCM does not illuminate the transmission warning lamp when the diagnostic runs and fails. • The TCM inhibits gear select & shift position learning and half-clutch learning. Condition for Clearing the DTC • The TCM turns OFF the transmission warning lamp when the diagnostic runs and does not fail. • A current DTC clears when the diagnostic runs and does not fail. • A history DTC clears when the diagnostic runs and does not fail. Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section. • If DTC U0100 is present, auto shift control is inhibited and poor shift quality (feel) will appear. • If DTC U0121 is present, lock up clutch may engage/disengage during an ABS event. Notice: • Diagnostic charts are different depending on the specification of the vehicle. DTC U0100, U0121 (Flash Code 42, 68) Schematic Reference: Transmission Controls Chart for without ABS Step Action Value(s) Yes No 1 Did you perform the Diagnostic System Check - — Go to Step 2 Go to Diagnostic System Check - Transmission Controls 2 1. Install the Tech 2. (TCM) Diagnostic Trouble Code (DTC) Does the DTC fail this ignition? — Go to Step 3 Go to Diagnostic Aids 3 Attempt to communicate with the engine control Does the Tech 2 communicate with the ECM? — Go to Step 4 Go to Diagnostic System Check - 4 1. Turn OFF the ignition. area network (CAN) Low and High circuits by Is the resistance within the specified value (parallel Ω resister 1 and the 120Ω resistor 2 should be 60 Ω)? 50 - 70 Ω Go to Step 11 Go to Step 5 |