P18BB 2015 GMC Sierra Code - Internal Mode Switch 'B' Circuit Stuck Off Invalid Voltage Range
Quick Answer
The P18BB diagnostic trouble code (DTC) for a 2015 GMC Sierra indicates an issue with the Internal Mode Switch 'B' Circuit being stuck off in an invalid voltage range. Common causes include Faulty Internal Mode Switch, Damaged wiring or connectors in the circuit, Issues with the vehicle's computer system. 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
- P18BB 2015 GMC Sierra indicates Internal Mode Switch 'B' Circuit Stuck Off Invalid Voltage Range.
- Common causes
- Common causes include Faulty Internal Mode Switch, Damaged wiring or connectors in the circuit, Issues with the vehicle's computer system.
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code P18BB 2015 GMC Sierra Description
The P18BB diagnostic trouble code (DTC) for a 2015 GMC Sierra indicates an issue with the Internal Mode Switch 'B' Circuit being stuck off in an invalid voltage range. The Internal Mode Switch (IMS) is a component of the transmission system that helps the vehicle's computer determine the current gear selection. In this case, the 'B' circuit refers to a specific part of the IMS that is not functioning correctly. When the circuit is stuck off in an invalid voltage range, it means that the voltage signal being sent to the vehicle's computer is outside of the expected parameters.
Common Causes of P18BB 2015 GMC Sierra
- Faulty Internal Mode Switch
- Damaged wiring or connectors in the circuit
- Issues with the vehicle's computer system
- Corrosion or moisture in the transmission system
- Electrical issues such as a blown fuse or relay
Symptoms of P18BB 2015 GMC Sierra
- Harsh or delayed shifting of gears
- Transmission slipping or jerking
- Inability to shift into certain gears
- Illumination of the Check Engine Light
- Reduced fuel efficiency
How to Fix P18BB 2015 GMC Sierra
- Diagnose the issue using a scan tool to retrieve the specific DTC and pinpoint the source of the problem.
- Inspect the Internal Mode Switch and associated wiring for any visible damage or corrosion.
- Test the voltage output of the Internal Mode Switch to determine if it is within the specified range.
- Replace the Internal Mode Switch if it is found to be faulty, and repair or replace any damaged wiring or connectors.
- Clear the DTC from the vehicle's computer memory and test drive the vehicle to ensure the issue has been resolved.
Cost to Fix P18BB 2015 GMC Sierra
The typical repair costs for addressing the P18BB code on a 2015 GMC Sierra can vary depending on the exact cause of the issue and the specific parts and labor required for the repair. In general, the cost of replacing the Internal Mode Switch and addressing any associated wiring or connector issues can range from $200 to $500. Additional costs may be incurred for diagnostic time, labor, and any other necessary repairs.
Need more information about the P18BB 2015 GMC Sierra code?
Need more information on how to fix the P18BB 2015 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P18BB 2015 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P18BB 2015 GMC Sierra Code
1. What does the OBDII code P18BB mean on a 2015 GMC Sierra?
The P18BB code indicates that the Internal Mode Switch (IMS) 'B' circuit is stuck off due to an invalid voltage range detected by the transmission control module (TCM).
2. What are the common symptoms of the P18BB code?
Symptoms may include a check engine light, erratic shifting, inability to change gears, or the transmission being stuck in one gear.
3. What causes the P18BB code on a 2015 GMC Sierra?
Common causes include a faulty internal mode switch, damaged wiring or connectors in the IMS circuit, or a malfunctioning transmission control module.
4. Can driving with the P18BB code cause further damage?
Yes, driving with this code can lead to transmission issues, reduced performance, and potential long-term damage if not addressed promptly.
5. How is the P18BB code diagnosed?
A mechanic will use a scan tool to confirm the code, inspect the IMS circuit wiring and connectors, test the internal mode switch, and check for proper voltage signals.
6. What repairs are typically needed to fix the P18BB code?
Repairs may include replacing the internal mode switch, repairing or replacing damaged wiring or connectors, and in rare cases, reprogramming or replacing the TCM.
7. How much does it cost to fix the P18BB code?
Repair costs vary but may range from $200 to $600, depending on whether the issue is with the IMS, wiring, or TCM.
8. Can the P18BB code be fixed without professional help?
DIY repairs are possible if you are experienced with automotive electrical systems, but diagnosing and repairing transmission-related issues often requires specialized tools and knowledge.
9. Is the P18BB code a common issue for the 2015 GMC Sierra?
It isn’t the most common issue, but it can occur due to wear and tear, particularly in high-mileage vehicles.
10. Can the P18BB code reappear after repairs?
Yes, if the root cause isn’t fully addressed, such as failing to check all wiring or properly calibrate the TCM, the code may return.
Discuss the causes and fixes for P18BB 2015 GMC Sierra OBDII Code
Code P18BB 2015 GMC Sierra 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.