AutoCodes – GMC – P18B7 2016 GMC Sierra

P18B7 2016 GMC Sierra Code - Internal Mode Switch 'C' 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: P18B7 2016 GMC Sierra indicates Internal Mode Switch 'C' 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.

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Code Popularity 189

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 P18B7 2016 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 C signal circuit voltage is between 0.966–1.68 V, for 1.75 s.

OBDII Code P18B7 2016 GMC Sierra - Internal Mode Switch 'C' Circuit Shorted - AutoCodes.com — P18B7 2016 GMC Sierra Code - Internal Mode Switch 'C' Circuit Shorted

What does this mean?

What are the Possible Causes of the DTC P18B7 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 P18B7 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 P18B7 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 P18B7 2016 GMC Sierra code?

Need more information on how to fix the P18B7 2016 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 P18B7 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code P18B7 on a 2016 GMC Sierra?

The common symptoms of OBDII code P18B7, which indicates an Internal Mode Switch 'C' Circuit Shorted, may include issues with shifting gears, erratic vehicle speed readings, and illuminated warning lights on the dashboard.

2. What could cause the OBDII code P18B7 to appear on a 2016 GMC Sierra?

The OBDII code P18B7 on a 2016 GMC Sierra is typically triggered by a short circuit in the Internal Mode Switch 'C' circuit. This can be caused by damaged wiring, a faulty internal mode switch, or a poor electrical connection.

3. How can I diagnose the Internal Mode Switch 'C' Circuit Shorted issue on my 2016 GMC Sierra?

To diagnose the Internal Mode Switch 'C' Circuit Shorted problem, you may need to use a diagnostic scanner to retrieve the specific trouble code. Additionally, a thorough visual inspection of the wiring and connections related to the internal mode switch is recommended.

4. Can I continue driving my 2016 GMC Sierra with the OBDII code P18B7 present?

It is not recommended to continue driving your 2016 GMC Sierra with the OBDII code P18B7 present, as it can lead to potential transmission issues and further damage. It is best to address the underlying problem promptly.

5. How can I repair the Internal Mode Switch 'C' Circuit Shorted issue on my 2016 GMC Sierra?

Repairing the Internal Mode Switch 'C' Circuit Shorted problem on a 2016 GMC Sierra may involve replacing the internal mode switch, repairing damaged wiring, or addressing any faulty electrical connections. It is advisable to consult a professional mechanic for proper diagnosis and repair.

6. Is the repair for OBDII code P18B7 on a 2016 GMC Sierra costly?

The cost of repairing the Internal Mode Switch 'C' Circuit Shorted issue on a 2016 GMC Sierra can vary depending on the extent of the damage and the specific components that need to be replaced. It is recommended to obtain quotes from reputable mechanics for an accurate estimate.

7. Can resetting the OBDII code P18B7 on a 2016 GMC Sierra solve the issue temporarily?

Resetting the OBDII code P18B7 on a 2016 GMC Sierra may temporarily clear the fault code, but if the underlying issue causing the Internal Mode Switch 'C' Circuit Shorted problem is not addressed, the code is likely to reappear. It is important to diagnose and repair the root cause of the issue.

8. Are there any safety concerns associated with the OBDII code P18B7 on a 2016 GMC Sierra?

The OBDII code P18B7 indicating an Internal Mode Switch 'C' Circuit Shorted on a 2016 GMC Sierra can pose safety concerns, especially if it affects the transmission's ability to shift gears properly. It is essential to address this issue promptly to ensure safe driving conditions.

9. How long does it typically take to repair the OBDII code P18B7 on a 2016 GMC Sierra?

The repair time for the Internal Mode Switch 'C' Circuit Shorted problem on a 2016 GMC Sierra can vary based on the extent of the damage and the availability of replacement parts. In general, the repair process may take a few hours to complete.

10. Can a DIY enthusiast fix the Internal Mode Switch 'C' Circuit Shorted issue related to OBDII code P18B7 on a 2016 GMC Sierra?

While some DIY enthusiasts may have the skills to address simpler automotive issues, repairing the Internal Mode Switch 'C' Circuit Shorted problem on a 2016 GMC Sierra often requires specialized tools and expertise. For optimal results and safety, it is recommended to seek professional help for this repair.