What Does P071C Mean?
The transmission mode switch A circuit is reporting a high voltage condition. This indicates the signal line is open, shorted to the reference/battery voltage, or the switch has failed in a high-resistance state. The TCM cannot determine which driving mode the driver has selected.
Common Causes
30%
Open circuit in the mode switch signal wire or disconnected connector
30%
Mode switch failed open or stuck in high-resistance position
20%
Signal wire shorted to battery voltage or reference voltage
10%
Corroded ground circuit preventing proper switch voltage division
10%
TCM connector issue at the mode switch input pin
Diagnostic Steps
1
Monitor the mode switch A voltage PID. If it reads at or near 5V (or battery voltage) regardless of switch position, the circuit is open or shorted high.
2
Disconnect the mode switch connector and jumper the signal pin to ground briefly. If the scan tool reading drops to 0V, the wiring to the TCM is intact and the switch is at fault.
3
Check the switch connector for spread, corroded, or backed-out pins that could cause an open circuit.
4
Measure continuity from the switch signal wire at the connector to the corresponding pin at the TCM connector. An open reading confirms a wiring break.
5
Inspect the ground circuit for the mode switch. An open ground causes the signal to float high.
Estimated Repair Cost
$50 - $300
Parts + labor, varies by vehicle and location
The transmission mode switch A circuit is reporting a high voltage condition. This indicates the signal line is open, shorted to the reference/battery voltage, or the switch has failed in a high-resistance state. The TCM cannot determine which driving mode the driver has selected.
The most common cause of P071C (Transmission Mode Switch "A" Circuit High) is: Open circuit in the mode switch signal wire or disconnected connector
Typical repair costs for P071C range from $50 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The transmission defaults to standard operating mode. The inability to select alternate modes is a convenience issue only. Repair at your next service appointment.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P071C to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
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