AutoCodes – GMC – P18BF 2014 GMC Sierra

P18BF 2014 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 2014 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.

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Code Popularity 245

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 23, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P18BF 2014 GMC Sierra Description

The internal mode switch indicates the Transmission Control Module (TCM) which gear position the vehicle operator has selected. The internal mode switch consists of 5 separate hall effect switches. Each hall effect switch is supplied with a 9 V reference circuit and a signal circuit from the TCM. Each signal circuit for each gear selector position will have either a voltage reading of 0.70–0.96 V indicating On or 1.68–2.38 V indicating Off. The voltage values on each internal mode switch circuit will change and are dependent on the position of the gear selector. The state of each internal mode switch A/B/C/P/S signal circuit is displayed on the scan tool. The Diagnostic Trouble Code (DTC) will be set when the TCM has detected the internal mode switch A signal circuit has an invalid voltage range of 0.70 – 0.96 V, for 2.7 s.

OBDII Code P18BF 2014 GMC Sierra - Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range - AutoCodes.com — P18BF 2014 GMC Sierra Code - Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range

What does this mean?

What are the Possible Causes of the DTC P18BF 2014 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 2014 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 2014 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 P18BF 2014 GMC Sierra code?

Need more information on how to fix the P18BF 2014 GMC Sierra code? Get Access to Factory Service Manuals

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P18BF 2014 GMC Sierra Code

1. What are the common symptoms of OBDII code P18BF in a 2014 GMC Sierra?

The common symptoms of OBDII code P18BF, Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range, in a 2014 GMC Sierra may include issues with shifting gears, the transmission not responding correctly, and potential warning lights on the dashboard.

2. What are the possible causes of OBDII code P18BF in a 2014 GMC Sierra?

Possible causes of OBDII code P18BF in a 2014 GMC Sierra include a faulty internal mode switch, damaged wiring or connectors related to the switch, or issues with the transmission control module.

3. How serious is OBDII code P18BF in a 2014 GMC Sierra?

OBDII code P18BF in a 2014 GMC Sierra should be addressed promptly to prevent potential transmission issues and ensure the vehicle operates safely. Ignoring this code could lead to further damage and costly repairs.

4. Can I continue driving my 2014 GMC Sierra with OBDII code P18BF?

It is not recommended to continue driving your 2014 GMC Sierra with OBDII code P18BF, as it may cause transmission problems and impact the overall performance of the vehicle. It is best to have the issue diagnosed and repaired as soon as possible.

5. How can I diagnose OBDII code P18BF in my 2014 GMC Sierra?

Diagnosing OBDII code P18BF in a 2014 GMC Sierra typically involves using a diagnostic scanner to retrieve the code, checking the internal mode switch and related components for proper functionality, and inspecting the wiring for any damage.

6. What are some repair tips for fixing OBDII code P18BF in a 2014 GMC Sierra?

Repair tips for fixing OBDII code P18BF in a 2014 GMC Sierra may include replacing the internal mode switch, repairing or replacing damaged wiring or connectors, and resetting the transmission control module after repairs are completed.

7. Can I reset OBDII code P18BF in my 2014 GMC Sierra without fixing the underlying issue?

While you can clear the code temporarily, it is not recommended to reset OBDII code P18BF in a 2014 GMC Sierra without addressing the underlying issue. The problem will likely resurface, and potential damage could occur if left unresolved.

8. How much does it typically cost to repair OBDII code P18BF in a 2014 GMC Sierra?

The cost to repair OBDII code P18BF in a 2014 GMC Sierra can vary depending on the exact cause of the issue, labor costs, and the specific components that need to be replaced. It is advisable to consult a mechanic for an accurate estimate.

9. Are there any recalls or service bulletins related to OBDII code P18BF in a 2014 GMC Sierra?

It is recommended to check with a GMC dealership or online resources to see if there are any recalls or service bulletins related to OBDII code P18BF in a 2014 GMC Sierra. Manufacturers may provide assistance if the issue is a known problem.

10. How can I prevent OBDII code P18BF from occurring in my 2014 GMC Sierra in the future?

Regular maintenance checks, prompt attention to any warning lights or unusual symptoms, and careful driving habits can help prevent OBDII code P18BF from occurring in your 2014 GMC Sierra. Keeping the vehicle in good condition and addressing issues promptly can reduce the risk of this code appearing.