3-4 Shift

Possible causes

• CommonLow or degraded transmission fluid
• CommonFailed or sticking shift solenoid for the 3-4 shift
• CommonWorn clutch pack or band used by the 3-4 shift
• CommonSticking valve in the valve body
• PossibleLow line pressure
• PossibleInternal seal leak in the circuit for that clutch

What you might notice

• Engine speed flaring during the 3-4 shift
• The 3-4 shift not happening, or happening very late
• Harsh bang on the 3-4 shift
• Limp mode
• Check engine light on

What to check, in order

1. Check the fluid level and condition first.
2. Confirm what actually happens on the 3-4 shift while driving. Flaring means the clutch is not gripping; a bang means it is arriving too hard; nothing at all points at the solenoid or the valve.
3. Read all codes. A solenoid code alongside this one usually names the cause directly.
4. Check for a corresponding gear ratio code, which would confirm the clutch is slipping rather than the shift not being commanded.
5. A pressure test tells you whether the hydraulics can deliver what that clutch needs.
6. Consider the vehicle's history. A single failing shift on a high-mileage transmission that has never been serviced is usually wear rather than a component fault.