P0121 means Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance Problem. P0121 occurs when the PCM has detected a throttle angle that is significantly higher or lower for the specified engine RPM (revolution per minute).
Open or short in the TPS wiring or circuit
Loose or contaminated TPS connector
Repair or replace TPS wiring or circuit
Tighten or replace TPS connector
P0724 = Torque Converter/Brake Switch B Circuit High
The purpose of this circuit is to prevent the engine from stalling while driving in lock-up condition, when
brakes are suddenly applied.
When the brake pedal is depressed, this switch sends a signals to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.
INSPECT STOP LAMP SWITCH ASSY
CHECK HARNESS AND CONNECTOR(STOP LAMP SWITCH ASSY - ECM)