P18B6 2017 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 2017 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 2017 GMC Sierra Description
What are the Possible Causes of the DTC P18B6 2017 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 2017 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 2017 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 2017 GMC Sierra code?
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Frequently Asked Questions about P18B6 2017 GMC Sierra Code
1. What does the OBDII code P18B6 mean on a 2017 GMC Sierra?
P18B6 indicates that the Internal Mode Switch 'B' circuit has a short, which typically refers to an electrical issue in the transmission range selector circuit.
2. What are the symptoms of code P18B6 in a 2017 GMC Sierra?
Common symptoms include the vehicle stuck in a specific gear, the inability to shift gears, illumination of the check engine light, or erratic shifting behavior.
3. What causes the P18B6 code to appear on a 2017 GMC Sierra?
The most common causes are damaged wiring, a short circuit in the Internal Mode Switch 'B' circuit, a faulty transmission range sensor, or a malfunctioning transmission control module (TCM).
4. Can I still drive my 2017 GMC Sierra with the P18B6 code?
While it may still be drivable, driving with this code can lead to further transmission issues or leave the vehicle stuck in an unsafe gear. It’s best to address the issue promptly.
5. How do I diagnose the P18B6 code on a GMC Sierra?
Start by checking the wiring and connectors for damage or corrosion. Use a multimeter to test the Internal Mode Switch 'B' circuit for shorts. If the wiring is intact, inspect the transmission range sensor and TCM.
6. How much does it cost to fix the P18B6 code on a 2017 GMC Sierra?
Repair costs can vary depending on the issue. Replacing a damaged wire or connector may cost $100-$200, while replacing the transmission range sensor or TCM can cost $300-$1,000 or more.
7. Can a bad battery cause the P18B6 code on a GMC Sierra?
A weak or failing battery is unlikely to directly cause the P18B6 code, but electrical issues related to low voltage could potentially exacerbate circuit problems.
8. What tools are needed to troubleshoot the P18B6 code?
You will need an OBDII scanner, a multimeter, and possibly a wiring diagram for the transmission system to accurately diagnose the issue.
9. Does the P18B6 code always mean the transmission range sensor is faulty?
No, while a faulty transmission range sensor is a common cause, the issue could also be due to damaged wiring, a short circuit, or a problem with the TCM.
10. Will clearing the P18B6 code fix the problem on my 2017 GMC Sierra?
Clearing the code may turn off the check engine light temporarily, but the underlying issue must be repaired to prevent the code from returning.
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