Fail-Safe Table
HINT:
This function minimizes the loss of ECT functions when a malfunction occurs in a sensor or solenoid.
FUNCTION TABLE
| Malfunction Part | Function |
|---|---|
| DTC P0710, P0712, P0713: ATF Temperature Sensor | Normally, the 1st to 2nd upshift is prohibited if the ATF temperature is below the specified value, and gears are shifted as follows: 1st --> 3rd --> 4th --> 5th. The ATF temperature sensor determines that the ATF temperature is higher than the specified value according to the driven distance and time. |
| DTC P0717: Speed Sensor (SP2) | During a speed sensor (SP2) malfunction, shift lever control is effected through the O/D direct clutch speed sensor (NCO) signal or crankshaft position (NE) signal. |
| DTC P0751, P0756, P0761, P0973, P0974, P0976, P0977, P0979, P0980, P0982, P0983: Shift Solenoid Valve S1, S2, S3 and S4 | During a solenoid valve S1, S2, S3, or S4 malfunction, the current to the solenoid valve is stopped, and shifting is effected by controlling the ON/OFF condition of the remaining normal solenoids. If all the solenoid valves are malfunctioning, the gear position will be based on the state of the hydraulic circuit at that time. |
| DTC P2716: Shift Solenoid Valve SLT | During a solenoid valve SLT malfunction, the current to the solenoid valve is stopped. Because this stops line pressure control, the shift shock increases. However, shifting is effected through normal clutch pressure control. |
| DTC P2725: Shift Solenoid Valve SLN | During a solenoid valve SLN malfunction, the current to the solenoid valve is stopped. Because this stops clutch pressure control, the shift shock increases. However, shifting is effected through normal clutch pressure control. |
| DTC P2757, P2759: Shift Solenoid Valve SLU | During a solenoid valve SLU malfunction, the current to the solenoid valve is stopped. Because this stops lock-up control and flex lock-up control, the shift shock increases and fuel economy decreases. |
Fail-safe function:
If any 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 as shown in Fig 1. The ECM also turns the shift solenoid valve SL OFF at the same time.
If both solenoids are malfunctioning, hydraulic control cannot be done electronically so it must be done manually. Manual shifting, as shown in Fig 1, must be performed. For a short circuit, the ECM stops sending current to the short circuit solenoid.