DTC P0731-871: Gear 1 Incorrect Ratio: Description
The hybrid vehicle control ECU uses the B1 and B2 brakes in the hybrid vehicle transmission assembly to switch between low and high gear.
Shifting control is performed using the line pressure circuit, B1 circuit, and B2 circuit. The hybrid vehicle control ECU detects abnormal line pressure by monitoring the operation of the fluid pressure switch in each circuit.
HINT:
Although the DTC title indicates an incorrect gear ratio, DTC P0731-871 relates to a malfunction of the B2 hydraulic circuit.
HINT:
- The preceding timing chart is for the first "Control the Shift Position" active test. The chart will differ for the second or later "Control the Shift Position" active test.
- If "Hi" is selected in the first "Control the Shift Position" active test, it may take more time to shift to "Hi".
| DTC No. | INF Code | DTC Detection Condition | Trouble Area |
|---|---|---|---|
| P0731 | 871 | Even if the fluid pressure was applied for low gear after the ST-on state occurred, the hybrid vehicle control ECU is not able to confirm that the fluid pressure was applied to the B2 circuit within the specified time. |
|
HINT:
ST-on is a state that occurs when the READY indicator in the combination meter blinks after the power switch is pressed with the brake pedal depressed.