AutoCodes – Chevrolet – P18BF 2018 Chevrolet Silverado

P18BF 2018 Chevrolet Silverado Code - Internal Mode Switch 'A' 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: P18BF 2018 Chevrolet Silverado indicates Internal Mode Switch 'A' 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 216

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 P18BF 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 A signal circuit has an invalid voltage range of 0.70 – 0.96 V, for 2.7 s.

OBDII Code P18BF 2018 Chevrolet Silverado - Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range - AutoCodes.com — P18BF 2018 Chevrolet Silverado Code - Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range

What does this mean?

What are the Possible Causes of the DTC P18BF 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 P18BF 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 P18BF 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 P18BF 2018 Chevrolet Silverado code?

Need more information on how to fix the P18BF 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 P18BF 2018 Chevrolet Silverado Code

1. What are common symptoms of OBDII code P18BF in a 2018 Chevrolet Silverado?

The common symptoms include issues with gear shifting, inability to start the vehicle, and the transmission staying in one gear.

2. What does the OBDII code P18BF 'Internal Mode Switch 'A' Circuit Stuck On Invalid Voltage Range' mean for a 2018 Chevrolet Silverado?

This code indicates that the internal mode switch 'A' circuit is stuck in an invalid voltage range, affecting the transmission's operation.

3. What are possible causes of OBDII code P18BF in a 2018 Chevrolet Silverado?

Possible causes include a faulty internal mode switch, wiring issues, damaged connectors, or problems with the transmission control module.

4. How can I diagnose OBDII code P18BF in my 2018 Chevrolet Silverado?

Diagnosing this code involves checking the internal mode switch for proper operation, inspecting the wiring and connectors for damage, and testing the transmission control module.

5. Can I drive my 2018 Chevrolet Silverado with OBDII code P18BF?

It's not advisable to drive the vehicle with this code as it may lead to transmission issues and potential safety hazards. It's best to address the problem promptly.

6. How can I repair OBDII code P18BF in a 2018 Chevrolet Silverado?

Repairing this code may involve replacing the internal mode switch, repairing or replacing damaged wiring or connectors, or reprogramming the transmission control module.

7. Is it safe to reset the OBDII code P18BF in my 2018 Chevrolet Silverado?

While resetting the code may temporarily clear the warning light, it's crucial to address the underlying issue causing the code to prevent further transmission problems.

8. Can a DIY enthusiast fix OBDII code P18BF in a 2018 Chevrolet Silverado?

Depending on your skill level and access to tools, you may be able to diagnose and repair this code yourself. However, complex transmission issues may require professional help.

9. How much does it cost to fix OBDII code P18BF in a 2018 Chevrolet Silverado?

The cost of fixing this code can vary based on the specific issue causing it. Costs may include parts and labor for replacing the internal mode switch, repairing wiring, or reprogramming the transmission control module.

10. Will OBDII code P18BF in a 2018 Chevrolet Silverado affect fuel efficiency?

While the direct impact on fuel efficiency may be minimal, unresolved transmission issues related to this code can lead to further damage and affect overall vehicle performance.