Fail-Safe Function
The following fail-safe functions allow vehicles to be driven even when sensor, switch or solenoid malfunction occurs.
Output Speed Sensor
Vehicle speed signal is input from combination meter.
Accelerator Pedal Position Signal and Throttle Position Signal
TCM controls the throttle opening angle to a predetermined fixed position to enable driving if a malfunctioning signal is input to TCM.
Transmission Range Switch
When the multiple transmission range switch signals are input to TCM, the priority of selector lever position becomes "D", "N", "R", "2" and "1" in order by internal TCM determination.
The use of 4GR is inhibited until normal operation resumes. Because the hydraulic circuit of the control valve is switched by manual valve according to the selector lever position, however, actual operating condition of vehicle becomes as follows.
| Actual lever position | Transmission range switch input signal | Running status |
|---|---|---|
| "P" | "P" position and other position signals | P |
| "R" | "R" position and other position signals | R |
| "N" | "N" position and other position signals | N |
| "D" | "D" position and other position signals | D1 <=> D2 <=> D3 <=> D4 |
| "2" | "2" position and other position signals (Except "1" position) | 21 <=> 22 <=> 23 |
| "2" position and "1" position signals | 21 <=> 22 | |
| "1" | "1" position and other position signals (Except "2" position) | 11 <=> 12 <=> 13 |
| "1" position and "2" position signals | 11 <=> 12 |
Shift Solenoid Valve A and B
If non-standard solenoid signal is sent to TCM, use of certain gears is limited. Refer to chart shown below.
| Shift position | Normal | Malfunction in solenoid valve A | Malfunction in solenoid valve B | Malfunction in solenoid valves A and B | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | Gear | A | B | Gear | A | B | Gear | A | B | Gear | |
| "D" position | • | • | 1st | - | •→x | 3rd | •→x | - | 3rd | - | - | 3rd |
| x | • | 2nd | - | •→x | x | - | - | - | ||||
| x | x | 3rd | - | x | x | - | - | - | ||||
| • | x | 4th | - | x | •→x | - | - | - | ||||
| "2" position | • | • | 1st | - | •→x | •→x | - | - | - | |||
| x | • | 2nd | - | •→x | x | - | - | - | ||||
| x | x | 3rd | - | x | x | - | - | - | ||||
| "1" position | • | • | 1st | - | •→x | •→x | - | - | - | |||
| x | • | 2nd | - | •→x | x | - | - | - | ||||
| x | x | 3rd | - | x | x | - | - | - | ||||
| •: Solenoid ON x: Solenoid OFF -: Non-standard condition |
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Line Pressure Solenoid Valve
If non-standard solenoid signal is sent to TCM, line pressure solenoid valve is turned OFF to achieve maximum oil pressure.
Torque Converter Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, torque converter clutch solenoid valve is turned OFF to release lock-up.
Overrun Clutch Solenoid Valve
If non-standard solenoid signal is sent to TCM, overrun clutch solenoid valve is turned OFF to engage overrun clutch. This will result in more effective engine brake during deceleration.