Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P173B: 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 output so that the line pressure is supplied to the clutch piston under the condition that overdrive clutch engagement is requested during running 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 a specified value or less when the engine is stopped or engagement of the over drive clutch is requested, the PCM detects a malfunction and stores a DTC.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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