AutoCodes – GMC – P18C0 2016 GMC Sierra

P18C0 2016 GMC Sierra Code - Internal Mode Switch 'B' 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: P18C0 2016 GMC Sierra indicates Internal Mode Switch 'B' 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 165

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 P18C0 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 B signal circuit has an invalid voltage range of 0.70 – 0.96 V for 2.7 s.

OBDII Code P18C0 2016 GMC Sierra - Internal Mode Switch 'B' Circuit Stuck On Invalid Voltage Range - AutoCodes.com — P18C0 2016 GMC Sierra Code - Internal Mode Switch 'B' Circuit Stuck On Invalid Voltage Range

What does this mean?

What are the Possible Causes of the DTC P18C0 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 P18C0 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 P18C0 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 P18C0 2016 GMC Sierra code?

Need more information on how to fix the P18C0 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 P18C0 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code P18C0 in a 2016 GMC Sierra?

The common symptoms of code P18C0 include issues with shifting gears, the inability to start the vehicle, and the check engine light illuminating on the dashboard.

2. What does the OBDII code P18C0 'Internal Mode Switch 'B' Circuit Stuck On Invalid Voltage Range' mean for a 2016 GMC Sierra?

This code indicates a problem with the internal mode switch 'B' circuit in the transmission range sensor, causing it to be stuck in an invalid voltage range.

3. What are the possible causes of OBDII code P18C0 in a 2016 GMC Sierra?

Possible causes of code P18C0 include a faulty internal mode switch, damaged wiring or connectors in the circuit, low transmission fluid levels, or internal transmission issues.

4. How can I diagnose and repair OBDII code P18C0 on my 2016 GMC Sierra?

Diagnosing and repairing code P18C0 typically involves checking the internal mode switch for proper operation, inspecting the wiring and connectors for damage, ensuring the transmission fluid levels are adequate, and addressing any internal transmission problems.

5. Can I continue driving my 2016 GMC Sierra with OBDII code P18C0 present?

It is not recommended to drive your vehicle with code P18C0 present, as it can lead to further damage to the transmission and other components. It is best to have the issue diagnosed and repaired as soon as possible.

6. Will resetting the OBDII code P18C0 in my 2016 GMC Sierra make it go away permanently?

Simply resetting the code may temporarily turn off the check engine light, but if the underlying issue causing code P18C0 is not addressed, the code is likely to return.

7. Is it safe to attempt to repair OBDII code P18C0 in a 2016 GMC Sierra on my own?

Repairing code P18C0 may require specialized knowledge and tools related to the transmission system. It is recommended to seek assistance from a qualified mechanic or technician to properly diagnose and repair the issue.

8. How much does it typically cost to repair OBDII code P18C0 on a 2016 GMC Sierra?

The cost of repairing code P18C0 can vary depending on the root cause of the issue, labor rates, and parts needed. It is advisable to obtain quotes from different repair shops to get an accurate estimate.

9. Can extreme weather conditions or rough driving cause OBDII code P18C0 to trigger in a 2016 GMC Sierra?

While extreme conditions may not directly cause code P18C0, they can exacerbate existing issues within the transmission system. It is important to maintain your vehicle and address any potential problems promptly to prevent codes like P18C0 from occurring.

10. How can I prevent OBDII code P18C0 from appearing in my 2016 GMC Sierra in the future?

Regular maintenance of your vehicle, including checking transmission fluid levels, inspecting wiring and connectors for damage, and addressing any issues promptly, can help prevent code P18C0 and other related transmission problems from occurring.