What it means
Voltage on the upshift switch line is below the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The upshift switch sends a higher-gear request to the transmission controller. The controller monitors voltage on the upshift signal line. This code sets when the voltage is below its expected range, which can result from a wire shorted to ground, a switch stuck in the pressed position, or a poor connector contact.
Common causes
Most likely first.
- Switch wire shorted to ground
- Switch stuck in pressed position
- Connector pins corroded - high contact resistance
Symptoms
- Check engine or transmission warning light may be on
- Upshift switch may not respond
- Manual upshifts may be unavailable
How to diagnose it
- Save freeze-frame data and check upshift-switch status and related transmission codes with a scan tool.
- With the vehicle safely parked, check whether live switch status shows an upshift request when the button or paddle is released.
- Inspect the upshift switch and accessible wiring for chafing, a short to ground, contamination, corrosion, or loose terminals.
- Watch live switch data while operating the control and gently moving the accessible harness to check for a stuck or changing signal.
- Test the switch contacts and signal wire for a short to ground using the manufacturer’s wiring diagram and specification.
Common fixes
- Repair a signal wire shorted to ground.
- Clean or replace corroded upshift-switch terminals.
- Secure or repair a loose connector in the switch circuit.
- Replace the upshift switch if it stays electrically pressed when released.
Can I keep driving?
Avoid relying on manual upshift requests; use a normal drive mode if shifts are otherwise predictable. If the signal causes unexpected gear changes or the transmission enters limp mode, stop driving when safe and arrange a check before continuing.
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.