P18AC GMC Code - Transmission Range Control Valve 2 Position Switch Circuit Stuck On
Quick Answer
As the vehicle speed increases, the transmission control module (TCM) receives input signals from the automatic transmission input and output speed sensors, throttle position sensor and other vehicle sensors to determine the precise moment to de-energize or “turn off” 1-2-3-4-5-6 solenoid and the solenoid. Common causes include Low transmission fluid, Faulty Transmission Range Control Valve 2 Position Switch, Transmission Range Control Valve 2 Position Switch harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P18AC GMC indicates Transmission Range Control Valve 2 Position Switch Circuit Stuck On.
- Common causes
- Common causes include Low transmission fluid, Faulty Transmission Range Control Valve 2 Position Switch, Transmission Range Control Valve 2 Position Switch harness is open or shorted.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P18AC GMC Description
What are the Possible Causes of the DTC P18AC GMC?
- Low transmission fluid
- Faulty Transmission Range Control Valve 2 Position Switch
- Transmission Range Control Valve 2 Position Switch harness is open or shorted
- Transmission Range Control Valve 2 Position Switch circuit poor electrical connection
- Faulty Control Valve Solenoid Body
How to Fix the DTC P18AC GMC?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P18AC GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P18AC GMC code?
Need more information on how to fix the P18AC GMC code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P18AC GMC code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P18AC GMC Code
No Frequently Asked Questions about P18AC GMC Code found.
Discuss the causes and fixes for P18AC GMC OBDII Code
Code P18AC GMC comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
