1-4 Upshift (Skip Shift) Solenoid Control Circuit Malfunction
The skip shift solenoid control circuit is not functioning properly, preventing the transmission from executing skip shift operation. This system allows automatic transmissions to skip gears under certain conditions for improved fuel efficiency, and its malfunction disables this feature.
What You Might Notice
- Skip shift feature is disabled or not working
- Skip shift indicator lamp is illuminated or flashing on dashboard
- Transmission may enter limp mode with reduced performance
- Harsh or delayed gear shifts
- Check Engine light is illuminated
Most Common Causes
- 1
Defective Skip Shift Solenoid
The solenoid valve itself has failed internally or electrically, preventing proper control signal response. This is the most common cause requiring solenoid replacement.
- 2
Shorted or Open Solenoid Wiring
The control circuit wiring to the solenoid has developed a break, short, or poor connection that interrupts signal transmission from the TCM. Check for damaged or corroded wires and connectors.
- 3
Low or Dirty Transmission Fluid
Insufficient transmission fluid level or degraded fluid quality can cause solenoid operation problems and trigger this code. Verify fluid condition and level first.
- 4
Transmission Control Module Programming Error
A software glitch or corrupted programming in the TCM may cause incorrect solenoid control signals. This may require reprogramming or TCM replacement.
How to Diagnose It
- 1
Check Defective Skip Shift Solenoid — The solenoid valve itself has failed internally or electrically, preventing proper control signal response. This is the most common cause requiring solenoid replacement.
- 2
Check Shorted or Open Solenoid Wiring — The control circuit wiring to the solenoid has developed a break, short, or poor connection that interrupts signal transmission from the TCM. Check for damaged or corroded wires and connectors.
- 3
Check Low or Dirty Transmission Fluid — Insufficient transmission fluid level or degraded fluid quality can cause solenoid operation problems and trigger this code. Verify fluid condition and level first.
- 4
Check Transmission Control Module Programming Error — A software glitch or corrupted programming in the TCM may cause incorrect solenoid control signals. This may require reprogramming or TCM replacement.
How to Fix It
- 1
Check and Top Off Transmission Fluid
Verify transmission fluid level is at the correct mark on the dipstick and inspect for contamination or dark discoloration. Replace fluid if dirty and refill to proper level.
- 2
Inspect Skip Shift Solenoid Wiring and Connectors
Visually inspect the solenoid control circuit wiring for corrosion, damage, or loose connections. Clean corroded connectors with electrical cleaner and reseat connections firmly.
- 3
Replace Skip Shift Solenoid
If wiring and fluid are acceptable, the solenoid itself has likely failed and requires replacement. Disconnect the solenoid and install a new unit, then clear the code and test.
- 4
Reprogram or Replace Transmission Control Module
If all hardware checks pass, the TCM may have a programming error. Have the module reprogrammed by a dealership or qualified shop, or replace the TCM if reprogramming fails.
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