P2778: Upshift Switch Circuit Intermittent/Erratic

P2778 is meant for an upshift switch signal that jumps around or drops out briefly instead of staying in one state. No manufacturer documents P2778 publicly. GM's 2023/2024 twin-clutch TCM and Ford's TR9070 split the same paddle input into low, high, implausible and stuck faults (P2775–P2777, P0815) but list no intermittent check, so on those cars a flickering contact will rather end up as one of these. CARB expects inputs to be watched for circuit and rationality faults, which is the frame this code fits. Practical causes are a clock spring with a cracked track that opens at certain wheel angles, a loose crimp in the column connector, or a worn paddle contact. Symptoms come and go: occasional ignored upshifts or unwanted gear requests.

Symptoms

• Upshift requests occasionally ignored
• Occasional unwanted upshift requests
• Fault comes and goes, often depending on steering angle

Most likely causes

• Clock spring track cracked, opening at certain steering angles
• Loose terminal or poor crimp in the column or wheel connector
• Worn or bouncing contact in the paddle

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the fluid level and condition according to the manufacturer
2. Gently move the wiring with the engine running and watch whether the reading changes.
3. Check the transmission connector
4. Read the data with a transmission-compatible scanner
5. Measure the solenoid valve circuit
6. Leave opening the transmission to a specialized repair shop

Good to know

• Repair difficulty: medium

What each character of P2778 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 7: Transmission
• 78: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2778?

Drive as little as possible and gently. If the transmission slips or stays in one gear, go slowly to a repair shop or call for a tow truck.

What causes code P2778?

The most common causes are: clock spring track cracked, opening at certain steering angles; loose terminal or poor crimp in the column or wheel connector; worn or bouncing contact in the paddle.

Related codes

• P2775Upshift Switch Circuit Range/Performance
• P2776Upshift Switch Circuit Low
• P2777Upshift Switch Circuit High
• P0815Upshift Switch Circuit
• P2782Downshift Switch Circuit Intermittent/Erratic

Sources

• law.cornell.edu: 13 CCR 1968.2
• gsi.ext.gm.com: 23OBDG07
• fordservicecontent.com: OBDSM2400OUTPUT 16Jul2024 WSM final V2 MCS7001

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.