AutoCodes – Chevrolet – P18B9 2015 Chevrolet Silverado

P18B9 2015 Chevrolet Silverado Code - Internal Mode Switch 'S' 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: P18B9 2015 Chevrolet Silverado indicates Internal Mode Switch 'S' 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 1,307

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 P18B9 2015 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 S signal circuit voltage is between 0.966–1.68 V, for 1.75 s.

OBDII Code P18B9 2015 Chevrolet Silverado - Internal Mode Switch 'S' Circuit Shorted - AutoCodes.com — P18B9 2015 Chevrolet Silverado Code - Internal Mode Switch 'S' Circuit Shorted

What does this mean?

What are the Possible Causes of the DTC P18B9 2015 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 P18B9 2015 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 P18B9 2015 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 P18B9 2015 Chevrolet Silverado code?

Need more information on how to fix the P18B9 2015 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 P18B9 2015 Chevrolet Silverado Code

1. What are the common symptoms of OBDII code P18B9 in a 2015 Chevrolet Silverado?

The common symptoms of OBDII code P18B9, Internal Mode Switch 'S' Circuit Shorted, in a 2015 Chevrolet Silverado may include issues with shifting gears, the transmission not responding correctly, and the check engine light illuminating on the dashboard.

2. What are the possible causes of OBDII code P18B9 in a 2015 Chevrolet Silverado?

The possible causes of OBDII code P18B9 in a 2015 Chevrolet Silverado include a faulty internal mode switch, damaged wiring or connectors related to the internal mode switch, or a short circuit in the internal mode switch circuit.

3. How can I diagnose OBDII code P18B9 in a 2015 Chevrolet Silverado?

Diagnosing OBDII code P18B9 in a 2015 Chevrolet Silverado typically involves using a scan tool to retrieve the trouble codes, inspecting the internal mode switch and its wiring for any visible damage, and testing the internal mode switch circuit for continuity and proper functioning.

4. Can I continue driving my 2015 Chevrolet Silverado with OBDII code P18B9?

It is not recommended to continue driving your 2015 Chevrolet Silverado with OBDII code P18B9, as it can lead to further damage to the transmission system. It is best to address the issue promptly to avoid more significant problems.

5. How can I repair OBDII code P18B9 in a 2015 Chevrolet Silverado?

Repairing OBDII code P18B9 in a 2015 Chevrolet Silverado may involve replacing the internal mode switch if it is found to be faulty, repairing or replacing damaged wiring or connectors, and clearing the trouble codes with a scan tool after the repair is completed.

6. Is it possible to reset OBDII code P18B9 in a 2015 Chevrolet Silverado without fixing the underlying issue?

While you can clear the trouble codes and reset OBDII code P18B9 in a 2015 Chevrolet Silverado with a scan tool, it is essential to address the underlying problem causing the code to prevent it from reoccurring and potentially causing more significant issues in the future.

7. How much does it typically cost to repair OBDII code P18B9 in a 2015 Chevrolet Silverado?

The cost of repairing OBDII code P18B9 in a 2015 Chevrolet Silverado can vary depending on the extent of the damage, the parts needed for the repair, and labor costs. It is recommended to consult with a mechanic or dealership for an accurate estimate.

8. Can a DIY enthusiast fix OBDII code P18B9 in a 2015 Chevrolet Silverado?

While some experienced DIY enthusiasts may be able to diagnose and repair OBDII code P18B9 in a 2015 Chevrolet Silverado, it is a complex issue related to the transmission system. It is advisable for most individuals to seek professional help to ensure the problem is correctly addressed.

9. How urgent is it to address OBDII code P18B9 in a 2015 Chevrolet Silverado?

It is essential to address OBDII code P18B9 in a 2015 Chevrolet Silverado promptly to prevent potential damage to the transmission system and ensure the safe operation of the vehicle. Ignoring the issue can lead to more severe problems and higher repair costs.

10. Will OBDII code P18B9 cause my 2015 Chevrolet Silverado to fail an emissions test?

OBDII code P18B9, indicating an Internal Mode Switch 'S' Circuit Shorted issue in a 2015 Chevrolet Silverado, can cause the vehicle to fail an emissions test. It is recommended to address the problem and ensure the issue is resolved before attempting to pass an emissions test.