AutoCodes – Chevrolet – P18C3 2017 Chevrolet Silverado

P18C3 2017 Chevrolet Silverado Code - Internal Mode Switch 'S' 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: P18C3 2017 Chevrolet Silverado indicates Internal Mode Switch 'S' 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 233

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 P18C3 2017 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 has an internal mode switch S signal circuit has an invalid voltage range of 0.70 – 0.96 V, for 2.7 s.

OBDII Code P18C3 2017 Chevrolet Silverado - Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range - AutoCodes.com — P18C3 2017 Chevrolet Silverado Code - Internal Mode Switch 'S' Circuit Stuck On Invalid Voltage Range

What does this mean?

What are the Possible Causes of the DTC P18C3 2017 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 P18C3 2017 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 P18C3 2017 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 P18C3 2017 Chevrolet Silverado code?

Need more information on how to fix the P18C3 2017 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 P18C3 2017 Chevrolet Silverado Code

1. What are the common symptoms of OBDII code P18C3 on a 2017 Chevrolet Silverado?

The common symptoms of code P18C3 include issues with shifting gears, erratic transmission behavior, and the malfunction indicator light (MIL) illuminating on the dashboard.

2. What could cause the Internal Mode Switch 'S' Circuit to be stuck on an invalid voltage range in a 2017 Chevrolet Silverado?

Possible causes of code P18C3 include a faulty internal mode switch, damaged wiring or connectors related to the switch, or issues with the transmission control module (TCM).

3. How can I diagnose OBDII code P18C3 on my 2017 Chevrolet Silverado?

Diagnosing code P18C3 involves using a diagnostic scan tool to retrieve the trouble codes, inspecting the internal mode switch and its connections, and checking for any visible signs of damage or corrosion.

4. Is it safe to continue driving my 2017 Chevrolet Silverado with OBDII code P18C3?

It is not recommended to drive your vehicle with code P18C3, as it can lead to transmission issues and potentially cause further damage. It's best to address the problem promptly.

5. What are some tips for repairing OBDII code P18C3 on a 2017 Chevrolet Silverado?

Repairing code P18C3 may involve replacing the internal mode switch, repairing or replacing damaged wiring or connectors, and clearing the trouble codes with a diagnostic tool after the repair is completed.

6. Can a DIY enthusiast fix OBDII code P18C3 on a 2017 Chevrolet Silverado?

While some experienced DIY enthusiasts may be able to address code P18C3 themselves, it's recommended to have a professional mechanic diagnose and repair the issue to ensure it is properly resolved.

7. How much does it typically cost to repair OBDII code P18C3 on a 2017 Chevrolet Silverado?

The cost of repairing code P18C3 can vary depending on the exact cause of the issue, the labor rates in your area, and whether any parts need to be replaced. It's advisable to obtain quotes from local mechanics for an accurate estimate.

8. Will resetting the trouble codes make OBDII code P18C3 go away on a 2017 Chevrolet Silverado?

Simply resetting the trouble codes may temporarily clear the MIL, but if the underlying issue causing code P18C3 is not addressed, the code is likely to reappear once the problem is detected again.

9. How urgent is it to address OBDII code P18C3 on a 2017 Chevrolet Silverado?

It is important to address code P18C3 promptly to prevent potential transmission issues and ensure the proper functioning of your vehicle. Ignoring the code could lead to further damage and safety concerns.

10. Can OBDII code P18C3 on a 2017 Chevrolet Silverado cause permanent damage if left unattended?

Continuing to drive with code P18C3 unresolved can potentially cause damage to the transmission or other related components over time. Therefore, it's crucial to address the issue as soon as possible to avoid costly repairs.