2-3 Shift
Diagnostic trouble code P0782 indicates a malfunction in the 2-3 shift sequence of the automatic transmission. The Powertrain Control Module (PCM) sets this code when it detects that the transmission is not shifting from second to third gear correctly, usually by comparing the input and output shaft speeds.
This code is considered high severity because a failure to shift properly can lead to severe internal transmission damage or leave the vehicle stranded. It should be diagnosed and repaired as soon as possible.
Common symptoms
- Check Engine Light illuminated
- Transmission fails to shift from 2nd to 3rd gear
- Harsh or delayed 2-3 shift
- Transmission slipping during the 2-3 shift
- Vehicle goes into limp mode
Likely causes
- Low or dirty transmission fluid
- Faulty 2-3 shift solenoid
- Clogged transmission fluid filter or internal passages
- Wiring or connector issues in the shift solenoid circuit
- Internal transmission mechanical failure (e.g., worn clutches or bands)
- Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM)
What to check before replacing parts
Check the transmission fluid level and condition.
Look for: Fluid that is low, burnt, or heavily contaminated with debris indicates a need for fluid replacement and possible internal damage.
Inspect the wiring and connectors to the transmission shift solenoids.
Look for: Look for frayed wires, corrosion, or loose connections that could interrupt the signal to the 2-3 shift solenoid.
Test the 2-3 shift solenoid using a digital multimeter.
Look for: Measure the resistance of the solenoid; if it is out of the manufacturer's specified range, the solenoid is faulty.
Perform a transmission line pressure test.
Look for: Compare the actual line pressure to the manufacturer's specifications to determine if the pump or pressure regulator is failing.
Scan for other related transmission codes and monitor live data.
Look for: Check the input and output speed sensor data during a test drive to verify if the PCM is commanding the shift and if the mechanical shift is actually occurring.
This page explains the generic P0782 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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