AutoCodes – GMC – P18BD 2014 GMC Sierra

P18BD 2014 GMC Sierra Code - Internal Mode Switch 'P' Circuit Stuck Off 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: P18BD 2014 GMC Sierra indicates Internal Mode Switch 'P' Circuit Stuck Off 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 151

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 P18BD 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 P signal circuit has an invalid voltage range of 1.68 – 2.38 V for 2.7 s.

OBDII Code P18BD 2014 GMC Sierra - Internal Mode Switch 'P' Circuit Stuck Off Invalid Voltage Range - AutoCodes.com — P18BD 2014 GMC Sierra Code - Internal Mode Switch 'P' Circuit Stuck Off Invalid Voltage Range

What does this mean?

What are the Possible Causes of the DTC P18BD 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 P18BD 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 P18BD 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 P18BD 2014 GMC Sierra code?

Need more information on how to fix the P18BD 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 P18BD 2014 GMC Sierra Code

1. What are the common symptoms of OBDII code P18BD on a 2014 GMC Sierra?

The common symptoms of code P18BD include issues with shifting gears, hesitation or jerking during acceleration, and the inability to engage certain gears.

2. What does the OBDII code P18BD 'Internal Mode Switch 'P' Circuit Stuck Off Invalid Voltage Range' mean for a 2014 GMC Sierra?

This code indicates a problem with the internal mode switch circuit in the transmission control module that is stuck in the off position due to an invalid voltage range.

3. What are the possible causes of OBDII code P18BD on a 2014 GMC Sierra?

Possible causes of code P18BD include a faulty internal mode switch, damaged wiring or connectors in the circuit, or issues with the transmission control module itself.

4. How serious is OBDII code P18BD on a 2014 GMC Sierra?

Code P18BD can cause drivability issues and affect the performance of the vehicle. It is recommended to address this code promptly to prevent further damage to the transmission system.

5. Can I continue to drive my 2014 GMC Sierra with OBDII code P18BD?

It is not advisable to continue driving with code P18BD present, as it can lead to transmission problems and potentially cause further damage. It is best to have the issue diagnosed and repaired as soon as possible.

6. How can I diagnose OBDII code P18BD on my 2014 GMC Sierra?

Diagnosing code P18BD typically involves using a scan tool to retrieve the code, checking the internal mode switch and its circuitry for faults, and inspecting the transmission control module for issues.

7. Is it possible to repair OBDII code P18BD on a 2014 GMC Sierra myself?

Repairing code P18BD may require technical knowledge and specialized tools. It is recommended to consult a professional mechanic or dealership for accurate diagnosis and repair of this issue.

8. How much does it cost to fix OBDII code P18BD on a 2014 GMC Sierra?

The cost of repairing code P18BD can vary depending on the exact cause of the issue, parts needed for replacement, and labor costs. It is best to obtain quotes from reputable repair shops for an accurate estimate.

9. Can resetting the OBDII system clear code P18BD on a 2014 GMC Sierra?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue causing code P18BD is not addressed, the code is likely to reappear. It is important to diagnose and repair the root cause of the problem.

10. How can I prevent OBDII code P18BD from appearing on my 2014 GMC Sierra in the future?

Regular maintenance and inspections of the transmission system, including the internal mode switch and its circuitry, can help prevent code P18BD from appearing. Addressing any issues promptly can also help avoid this code in the future.