AutoCodes – Chevrolet – P18B9 2014 Chevrolet Silverado

P18B9 2014 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 2014 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 241

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 2014 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 2014 Chevrolet Silverado - Internal Mode Switch 'S' Circuit Shorted - AutoCodes.com — P18B9 2014 Chevrolet Silverado Code - Internal Mode Switch 'S' Circuit Shorted

What does this mean?

What are the Possible Causes of the DTC P18B9 2014 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 2014 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 2014 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 2014 Chevrolet Silverado code?

Need more information on how to fix the P18B9 2014 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 2014 Chevrolet Silverado Code

1. What does the OBDII code P18B9 mean on a 2014 Chevrolet Silverado?

The P18B9 code indicates that the Internal Mode Switch "S" Circuit in the transmission has a short, which can affect gear selection and shifting.

2. What are the common symptoms of the P18B9 code?

Symptoms may include erratic shifting, the transmission being stuck in one gear, the check engine light illuminating, or reduced vehicle performance.

3. What causes the P18B9 code to appear?

This code is commonly caused by a shorted or open circuit in the Internal Mode Switch "S" wiring, a faulty Internal Mode Switch, damaged connectors, or a malfunctioning transmission control module (TCM).

4. Can I drive with the P18B9 code on my 2014 Silverado?

Driving with the P18B9 code is not recommended, as it may lead to further transmission issues or unsafe driving conditions due to erratic shifting.

5. How do you diagnose the P18B9 code?

Diagnosing this code involves using a scan tool to check for related codes, inspecting the Internal Mode Switch wiring and connectors for damage, and testing the switch itself for proper function.

6. What parts might need to be replaced to fix the P18B9 code?

Repairs may involve replacing the Internal Mode Switch, repairing or replacing damaged wiring or connectors, or, in rare cases, replacing the transmission control module.

7. How much does it cost to fix the P18B9 code on a Chevrolet Silverado?

Repair costs can vary, but diagnosing and fixing wiring issues may cost $100-$300, while replacing the Internal Mode Switch could cost $300-$600, depending on labor rates.

8. Can a software update fix the P18B9 code?

While uncommon, a TCM software update may resolve the issue if itâ€™s related to a programming problem. However, physical wiring or switch issues typically require repairs or replacement.

9. What tools are needed to troubleshoot the P18B9 code?

Troubleshooting requires a scan tool capable of reading transmission codes, a multimeter to test circuits, and potentially wiring diagrams for the transmission system.

10. Does the P18B9 code always mean the Internal Mode Switch is faulty?

No, the code can also be caused by wiring issues, damaged connectors, or problems with the TCM, so thorough diagnosis is essential before replacing any parts.