Upshift Switch Circuit Intermittent/Erratic

What it means

P2778 is stored when the Upshift Switch signal drops out or jumps erratically for short periods. Intermittent faults are almost always connector, wiring or vibration related.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

Symptoms

• Check engine light on
• Rough or unstable idle
• Hesitation or poor acceleration
• Increased fuel consumption
• Possible limp mode with reduced power

Common causes

1. Damaged, chafed or corroded wiring in the Upshift Switch circuit
2. Corroded, loose or water-damaged connector terminals
3. Failed Upshift Switch component (sensor, solenoid or actuator)
4. Poor ground connection for the module or component
5. Faulty control module driver (rare, confirm all else first)

How to diagnose

1. Read freeze frame data and note when the code set (cold start, under load, after rain)
2. Inspect the Upshift Switch connector for bent pins, corrosion and water; wiggle the harness with the engine running and watch live data
3. Measure supply voltage and ground at the connector with the key on
4. Check the signal wire for shorts to ground or battery and for continuity to the control module
5. Test or substitute the Upshift Switch only after wiring and connectors are confirmed good
6. Clear the code and complete a drive cycle to confirm the repair

Related codes

Nearby codes in this group

• P2777Upshift Switch Circuit High
• P2779Downshift Switch Circuit Range/Performance
• P2776Upshift Switch Circuit Low
• P2780Downshift Switch Circuit Low
• P2775Upshift Switch Circuit Range/Performance
• P2781Downshift Switch Circuit High
• P2774Four Wheel Drive (4WD) Low Switch Circuit High
• P2782Downshift Switch Circuit Intermittent/Erratic