What Does P071D Mean?
The transmission mode switch B circuit has a general malfunction. Vehicles with multiple mode switches or a multi-function mode selector use a B circuit as a secondary input. The TCM is unable to read a valid signal from this switch. Some or all driving mode selections may be non-functional.
Common Causes
35%
Faulty transmission mode switch B assembly
30%
Damaged wiring or connector in the B circuit
15%
Corroded or contaminated switch contacts
10%
Blown fuse or missing power supply to the switch circuit
10%
TCM fault or software issue not recognizing the B switch input
Diagnostic Steps
1
Monitor the mode switch B PID in live data while cycling through all available mode positions. Verify each mode change is reflected in the data.
2
Check for power, ground, and reference voltage at the mode switch B connector with KOEO. All circuits must be within specification.
3
Inspect the switch and connector for physical damage, liquid intrusion, corrosion, or loose pins.
4
Measure switch contact resistance in each position and compare to manufacturer specs. Each position should produce a unique, consistent resistance.
5
Verify the fuse and wiring continuity from the switch to the TCM. Repair any open or high-resistance connections.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The transmission mode switch B circuit has a general malfunction. Vehicles with multiple mode switches or a multi-function mode selector use a B circuit as a secondary input. The TCM is unable to read a valid signal from this switch. Some or all driving mode selections may be non-functional.
The most common cause of P071D (Transmission Mode Switch "B" Circuit) is: Faulty transmission mode switch B assembly
Typical repair costs for P071D range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The transmission will function in its default mode. Specific mode selections may be unavailable. This is a convenience concern, not a safety issue.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P071D 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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