AUTOMATIC TRANSMISSION SYSTEM FAIL-SAFE CHART


  1. FAIL-SAFE CHART

    This function minimizes the loss of the ECT functions when a malfunction occurs in each sensor or solenoid.

    Malfunction Part Function

    DTC P0710, P0712 and P0713:

    ATF Temperature Sensor

    		 During malfunction of ATF temperature sensor, system fixes ATF at 80°C (176°F)

    DTC P0722:

    No. 2 Vehicle Speed Sensor (SP2)

    		 During No. 2 vehicle speed sensor malfunction, shift lever control is effected through input speed sensor signal (NC0) or engine speed signal (NE)

    DTC P0973, P0974, P0976 and P0977:

    Shift Solenoid Valve S1, S2

    		 Current to the failed solenoid valve is cut off and control is effected by operating other solenoid valves with normal operation

    DTC P2716:

    Shift Solenoid Valve SLT

    During solenoid valve SLT malfunction, current to solenoid valve is stopped

    Because this stops line pressure control, shift shock increases

    However, shifting is effected through normal clutch pressure control

    DTC P2769 and P2770:

    Shift Solenoid Valve SL

    During solenoid valve SL malfunction, current to solenoid valve is stopped

    Because this stops lock-up control, fuel economy decreases

    Fail-safe function:

    If either of the shift solenoid valve circuits develops an open or short, the ECM turns the other shift solenoid ON and OFF to shift to the gear positions shown in the table below. The ECM also turns the shift solenoid valve SL OFF at the same time. If both solenoids are malfunctioning, electronic hydraulic control does not operate and must be performed manually. Manual shifting as shown in the following table must be performed.

    In case of a short circuit, the ECM stops sending current to the circuit.

    Position Normal Shift Solenoid S1 Malfunctioning Shift Solenoid S2 Malfunctioning Both Solenoids Malfunctioning
    Solenoid valve Gear Solenoid valve Gear Solenoid valve Gear Gear when shift selector is manually operated
    S1 S2 S1 S2 S1 S2
    D ON OFF 1st X ON 3rd ON X 1st O/D
    ON ON 2nd X ON 3rd OFF X O/D O/D
    OFF ON 3rd X ON 3rd OFF X O/D O/D
    OFF OFF O/D X OFF O/D OFF X O/D O/D
    2 ON OFF 1st X ON 3rd ON X 1st 3rd
    ON ON 2nd X ON 3rd OFF X 3rd 3rd
    OFF ON 3rd X ON 3rd OFF X 3rd 3rd
    L ON OFF 1st X OFF 1st ON X 1st 1st
    ON ON 2nd X ON 2nd ON X 1st 1st

    Tech Tips

    X: Malfunction