DTC P173B (2021)
DTC P173B: Transmission Fluid Pressure Sensor Performance Low
General Description
| Capacity of Over Drive Clutch | Shift Solenoid Valve A | ||
| ON (12 V) | OFF (0 V) | ||
| Shift Solenoid Valve B | ON (12 V) | ON | OFF |
| OFF (0 V) | OFF | OFF | |
Shift solenoid valve A is installed on the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM) to apply line pressure to shift valve A. The signal from the PCM is outputted so that the line pressure is supplied to the clutch piston under the condition that the overdrive clutch engagement is requested while driving at 44 mph (70 km/h) or more. When the signal to shift solenoid valve A from the PCM is ON, and the line pressure is applied to shift valve A, it operates against the shift valve A spring. When the signal to shift solenoid valve A from the PCM is OFF, and the line pressure is discharged, shift valve A is inactive. The PCM monitors the transmission fluid pressure sensor. If the transmission fluid pressure sensor pressure is at specified value or less when engagement of the over drive clutch is requested, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 3.0 seconds or more |
| DTC Type | Two drive cycle, MIL on, Shift position indicator blinks |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Vehicle speed [VEHICLE SPEED] | 0 mph (0 km/h) | - |
| 12 volt battery voltage [BATTERY VOLTAGE] | 11 V | - |
| State of the vehicle | Engine driving mode | |
[ ]: HDS Parameter
Malfunction Threshold
The transmission fluid pressure sensor value is 120 kPa (900 mmHg, 35.4 inHg) or less for at least 3.0 seconds when engagement of the over drive clutch is requested.
Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- Transmission fluid pressure sensor failure
- PCM internal failure
Confirmation Procedure
Operating Condition
- Enter the maintenance mode, then start the engine. Hold the engine speed [ENGINE SPEED] at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
- Drive the vehicle at a steady speed of 44 mph (70 km/h) or more for at least 10 seconds with engine drive mode.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, the shift position indicator blinks and a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.