AutoCodes – Chevrolet – P18B6 2018 Chevrolet Silverado

P18B6 2018 Chevrolet Silverado Code - Internal Mode Switch 'B' 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: P18B6 2018 Chevrolet Silverado indicates Internal Mode Switch 'B' 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 484

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 P18B6 2018 Chevrolet Silverado 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 voltage is between 0.966–1.68 V, for 1.75 s.

OBDII Code P18B6 2018 Chevrolet Silverado - Internal Mode Switch 'B' Circuit Shorted - AutoCodes.com — P18B6 2018 Chevrolet Silverado Code - Internal Mode Switch 'B' Circuit Shorted

What does this mean?

What are the Possible Causes of the DTC P18B6 2018 Chevrolet Silverado?

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 P18B6 2018 Chevrolet Silverado?

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 P18B6 2018 Chevrolet Silverado 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 P18B6 2018 Chevrolet Silverado code?

Need more information on how to fix the P18B6 2018 Chevrolet Silverado 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 P18B6 2018 Chevrolet Silverado Code

1. What are the common symptoms of OBDII code P18B6 in a 2018 Chevrolet Silverado?

The common symptoms of code P18B6 include issues with shifting gears, rough shifting, incorrect gear selection, or the transmission not responding properly.

2. What does the Internal Mode Switch 'B' Circuit Shorted mean in a 2018 Chevrolet Silverado?

The Internal Mode Switch 'B' Circuit Shorted refers to a malfunction in the circuit associated with the internal mode switch in the transmission control module.

3. What are the possible causes of the Internal Mode Switch 'B' Circuit Shorted code in a 2018 Chevrolet Silverado?

Possible causes of the P18B6 code include a faulty internal mode switch, damaged wiring or connectors in the circuit, a defective transmission control module, or a short circuit.

4. How can I diagnose the Internal Mode Switch 'B' Circuit Shorted issue in my 2018 Chevrolet Silverado?

Diagnosing the P18B6 code involves using a scan tool to retrieve the trouble codes, checking the internal mode switch and its wiring for damage, and testing the circuit for continuity and shorts.

5. Can I continue driving my 2018 Chevrolet Silverado with the P18B6 code present?

It is not recommended to continue driving your vehicle with the P18B6 code present, as it can lead to further transmission issues and potentially cause damage to other components.

6. How can the Internal Mode Switch 'B' Circuit Shorted issue in a 2018 Chevrolet Silverado be repaired?

Repairing the P18B6 code typically involves replacing the internal mode switch if faulty, repairing or replacing damaged wiring or connectors, and resetting the fault codes with a scan tool.

7. Is it possible to reset the P18B6 code in a 2018 Chevrolet Silverado without fixing the underlying issue?

Resetting the code without addressing the underlying issue may temporarily clear the fault code, but the problem will likely reoccur until the root cause is fixed.

8. Can a DIY enthusiast fix the Internal Mode Switch 'B' Circuit Shorted problem in a 2018 Chevrolet Silverado?

While some DIY enthusiasts may have the skills to diagnose and repair the P18B6 code, it is recommended to consult a professional mechanic for proper diagnosis and repair to ensure the issue is resolved correctly.

9. Will the P18B6 code cause my 2018 Chevrolet Silverado to go into limp mode?

In some cases, the Internal Mode Switch 'B' Circuit Shorted issue can trigger the vehicle to go into limp mode, limiting the transmission's functionality to prevent further damage until the problem is addressed.

10. How long does it typically take to repair the P18B6 code in a 2018 Chevrolet Silverado?

The repair time for the Internal Mode Switch 'B' Circuit Shorted issue can vary depending on the exact cause and extent of the problem, but it usually takes a few hours to a full day for a mechanic to diagnose and fix the issue.