P18BF 2016 GMC Sierra Code - Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range
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
- P18BF 2016 GMC Sierra indicates Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range.
- 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 P18BF 2016 GMC Sierra Description
What are the Possible Causes of the DTC P18BF 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 P18BF 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 P18BF 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.
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Frequently Asked Questions about P18BF 2016 GMC Sierra Code
1. What does the OBDII code P18BF mean on a 2016 GMC Sierra?
The P18BF code indicates an issue with the Internal Mode Switch 'A' circuit, specifically that it is stuck on an invalid voltage range.
2. What are the symptoms of the P18BF code on a 2016 GMC Sierra?
Common symptoms include transmission shifting issues, the vehicle being stuck in one gear, or the check engine light being illuminated.
3. What causes the P18BF code to appear on a 2016 GMC Sierra?
The code can be caused by a faulty internal mode switch, damaged wiring or connectors in the switch circuit, or a malfunctioning transmission control module (TCM).
4. Can I drive my 2016 GMC Sierra with the P18BF code?
Driving with this code is not recommended, as it can lead to poor transmission performance and potentially cause further damage to the transmission system.
5. How is the P18BF code diagnosed on a 2016 GMC Sierra?
A technician will use a scan tool to verify the code, inspect the internal mode switch and its wiring for damage, and test the circuit for proper voltage and continuity.
6. How do you fix the P18BF code on a 2016 GMC Sierra?
Repairs may involve replacing a faulty internal mode switch, repairing or replacing damaged wiring, or reprogramming or replacing the TCM if necessary.
7. How much does it cost to fix the P18BF code on a 2016 GMC Sierra?
The cost can vary depending on the root cause, but replacing an internal mode switch typically costs between $200 and $500, including parts and labor.
8. Can a bad battery cause the P18BF code?
While unlikely, a weak or faulty battery can cause voltage issues that may trigger the code. It’s a good idea to check the battery as part of the diagnostic process.
9. What is the internal mode switch in a 2016 GMC Sierra?
The internal mode switch is a part of the transmission system that communicates the gear position to the TCM for proper shifting and operation.
10. Can clearing the P18BF code with a scan tool fix the issue?
Clearing the code may turn off the check engine light temporarily, but the underlying issue must be resolved to prevent the code from returning.
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