What it means
The TCM detects a fault during the 2-to-3 upshift. Gear ratio after shift command does not match third gear expected ratio.
At a glance
- Usually lights the check-engine light
How it works
During the 2-to-3 upshift, the TCM checks speed-sensor readings to verify that the transmission reaches the expected third-gear ratio. P0782 sets when the ratio after the shift command does not match that target, directing diagnosis toward Shift Solenoid B control, the 2-3 clutch, or the related hydraulic circuit.
Common causes
Most likely first.
- Shift solenoid B faulty
- 2-3 clutch slipping
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Review freeze-frame data and related codes to confirm the fault occurred during the 2-to-3 shift and check for Shift Solenoid B faults.
- Check transmission fluid level and condition according to the manufacturer’s procedure.
- Inspect Shift Solenoid B wiring and transmission connectors for damage, corrosion, loose pins, or fluid intrusion.
- Compare commanded gear with input and output speeds in live data during a controlled 2-to-3 shift to see whether the ratio slips or fails to change.
- Test Shift Solenoid B operation and check 2-3 shift pressure against the manufacturer’s specifications.
- If solenoid and pressure tests pass, inspect the 2-3 clutch and its hydraulic passages for wear or leakage.
Common fixes
- Correct low fluid or replace degraded fluid using the specified type and procedure.
- Repair damaged wiring or poor connector contacts at Shift Solenoid B.
- Replace Shift Solenoid B if testing confirms it is faulty.
- Repair a valve body or hydraulic fault affecting the 2-3 shift.
- Repair or replace the 2-3 clutch if it is worn or damaged.
Can I keep driving?
Avoid hard acceleration and towing if the transmission slips or shifts harshly from second to third; continued slipping can overheat and damage the 2-3 clutch. If the transmission cannot make the shift reliably, limit driving and arrange repair.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.