Transmission Mode Switch Circuit High
The P071C code indicates that the Powertrain Control Module (PCM) has detected a high voltage condition in the transmission mode switch circuit. This switch, often part of the manual shift lever or range selector, tells the PCM which gear position (Park, Reverse, Neutral, Drive) is selected. A high voltage reading typically means there is a short to power, a faulty switch, or a wiring issue. This can cause incorrect gear selection, harsh shifting, or transmission malfunction.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission stuck in one gear or limp mode
- Harsh or erratic shifting
- Incorrect gear display on dashboard
- Vehicle may not start or shift out of Park
2. Most Common Causes
- Faulty transmission mode switch
- Short to voltage in the switch circuit
- Damaged wiring or connector
- Corrosion or poor electrical connection
- Faulty PCM (rare)
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the transmission mode switch and wiring for damage, corrosion, or loose connections.
Step 3: Test the switch circuit voltage with a multimeter; compare to manufacturer specifications.
Step 4: Check for shorts to power or ground in the wiring harness.
Step 5: If wiring is okay, replace the transmission mode switch and clear codes.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. The transmission may shift erratically or enter limp mode, which can cause unsafe driving conditions. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically between $50 and $150 for parts and labor, depending on the vehicle and shop rates.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.