P18B6 2016 GMC Sierra Code - Internal Mode Switch 'B' Circuit Shorted
Quick Answer
The internal mode switch indicates the Transmission Control Module (TCM) which gear position the vehicle operator has selected. Common causes include Faulty Transmission Internal Mode Switch, Transmission Internal Mode Switch harness is open or shorted, Transmission Internal Mode Switch circuit poor electrical connection. 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
- P18B6 2016 GMC Sierra indicates Internal Mode Switch 'B' Circuit Shorted.
- Common causes
- Common causes include Faulty Transmission Internal Mode Switch, Transmission Internal Mode Switch harness is open or shorted, Transmission Internal Mode Switch circuit poor electrical connection.
- 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 P18B6 2016 GMC Sierra Description
What are the Possible Causes of the DTC P18B6 2016 GMC Sierra?
- Faulty Transmission Internal Mode Switch
- Transmission Internal Mode Switch harness is open or shorted
- Transmission Internal Mode Switch circuit poor electrical connection
- Faulty Transmission Control Module (TCM)
How to Fix the DTC P18B6 2016 GMC Sierra?
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 P18B6 2016 GMC Sierra 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 P18B6 2016 GMC Sierra code?
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Frequently Asked Questions about P18B6 2016 GMC Sierra Code
1. What does the OBDII code P18B6 mean in a 2016 GMC Sierra?
P18B6 indicates an issue with the Internal Mode Switch 'B' Circuit, specifically a short circuit within the system.
2. What are the common symptoms of the P18B6 code in a GMC Sierra?
Symptoms may include the transmission failing to shift properly, being stuck in one gear, or the illumination of the check engine light.
3. What causes the P18B6 code to appear?
This code is typically caused by a short in the Internal Mode Switch 'B' Circuit, damaged wiring, a faulty internal mode switch, or a malfunctioning transmission control module (TCM).
4. Can I still drive my GMC Sierra with the P18B6 code?
It is not recommended to drive with this code present, as transmission issues can worsen and potentially lead to unsafe driving conditions.
5. How is the P18B6 code diagnosed?
A mechanic will use a scan tool to read the code, inspect the wiring and connectors for damage, and test the internal mode switch and associated circuits.
6. Is replacing the internal mode switch the only way to fix the P18B6 code?
Not always. The issue could also be with the wiring or connectors, so it’s important to thoroughly diagnose the problem before replacing the switch.
7. How much does it cost to repair the P18B6 code in a 2016 GMC Sierra?
Repair costs vary depending on the root cause, but typical expenses range from $150 to $500, including parts and labor.
8. What tools are needed to troubleshoot the P18B6 code?
Common tools include an OBDII scanner, a multimeter to test circuits, and basic hand tools for inspecting and repairing wiring or connectors.
9. Can a faulty transmission control module (TCM) cause the P18B6 code?
Yes, a malfunctioning TCM can sometimes trigger this code, although it is less common than wiring or switch issues.
10. How can I prevent the P18B6 code from occurring again?
Regular maintenance, including inspecting wiring and connectors for wear or damage, can help prevent this code from recurring.
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