Upshift Switch Circuit High
The P2777 code indicates that the powertrain control module (PCM) has detected a high voltage signal from the upshift switch circuit. This switch is typically located on the gearshift lever or steering wheel and signals the transmission to upshift. A high voltage condition suggests a short to power, a faulty switch, or a wiring issue. This can prevent proper upshifting, leading to poor performance and potential transmission damage.
01. Most Common Causes
- Faulty upshift switch
- Short to power in the upshift switch circuit
- Damaged wiring or connector
- Corroded terminals
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission stuck in gear or fails to upshift
- Reduced fuel economy
- Erratic shifting behavior
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Visually inspect the upshift switch and its wiring for damage, corrosion, or loose connections.
Step 3: Test the upshift switch with a multimeter for proper resistance and continuity.
Step 4: Check for a short to power by measuring voltage at the switch connector with the ignition on.
Step 5: If wiring and switch are okay, test the PCM output signals to rule out a faulty PCM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause erratic shifting or transmission damage. Have it diagnosed promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause and vehicle model.