What it means
Same as P071A with the signal shorted to supply. 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
Transmission mode switch A tells the control module which transmission mode has been selected. P071C sets when the module sees switch A's signal above its expected range, consistent with the signal being pulled toward supply voltage.
Common causes
Most likely first.
- Signal shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Check freeze-frame and live data for mode switch A to confirm the high reading and note the selector position and conditions when it occurs.
- With the vehicle safely parked, move the selector through its available positions and compare the displayed switch A state with the selected mode.
- Inspect switch A's connector and harness for corrosion, moisture, pushed-back pins, and wiring pinched against a powered wire.
- Monitor switch A live data while gently moving the harness to identify a connection or rubbed section that makes the signal go high.
- Using the wiring diagram, check for a short from switch A's signal to supply and test the switch and connector against the manufacturer's specification.
Common fixes
- Clean and secure corroded or loose switch A connector terminals.
- Repair signal wiring shorted to a supply wire.
- Replace damaged connector seals or terminals that admit moisture or lose contact.
- Replace mode switch A if it produces an out-of-range high signal with wiring verified.
Can I keep driving?
Limit driving if the transmission shifts harshly, delays shifts, or cannot select modes reliably, since it may use a protective gear strategy. Stop if it slips or shifts unpredictably.
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.