AutoCodes – Chevrolet – P18B5 Chevrolet

P18B5 Chevrolet Code - Internal Mode Switch 'A' 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: P18B5 Chevrolet indicates Internal Mode Switch 'A' 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 1,783

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 P18B5 Chevrolet 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 voltage is between 0.966–1.68 V, for 1.75 s.

OBDII Code P18B5 Chevrolet - Internal Mode Switch 'A' Circuit Shorted - AutoCodes.com — P18B5 Chevrolet Code - Internal Mode Switch 'A' Circuit Shorted

What does this mean?

What are the Possible Causes of the DTC P18B5 Chevrolet?

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 P18B5 Chevrolet?

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 P18B5 Chevrolet 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 P18B5 Chevrolet code?

Need more information on how to fix the P18B5 Chevrolet code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific Chevrolet Models

P18B5 2014 Chevrolet Silverado — Internal Mode Switch 'A' Circuit Shorted
P18B5 2015 Chevrolet Silverado — Internal Mode Switch 'A' Circuit Shorted
P18B5 2016 Chevrolet Silverado — Internal Mode Switch 'A' Circuit Shorted
P18B5 2017 Chevrolet Silverado — Internal Mode Switch 'A' Circuit Shorted
P18B5 2018 Chevrolet Silverado — Internal Mode Switch 'A' Circuit Shorted

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 P18B5 Chevrolet Code

1. What are the common symptoms of OBDII code P18B5 in a Chevrolet related to the Internal Mode Switch 'A' Circuit Shorted?

- Common symptoms include issues with shifting gears, transmission slipping, and the vehicle going into limp mode.

2. What causes the Internal Mode Switch 'A' Circuit Shorted code P18B5 in a Chevrolet?

- The code P18B5 is usually triggered by a short circuit in the internal mode switch 'A' circuit, which can be caused by wiring issues or a faulty internal mode switch.

3. How can I diagnose the Internal Mode Switch 'A' Circuit Shorted code P18B5 in my Chevrolet?

- A thorough inspection of the internal mode switch, wiring harness, and connectors is recommended to diagnose the issue. Using a multimeter to test the circuit continuity can also help pinpoint the problem.

4. Can I drive my Chevrolet with the OBDII code P18B5 Internal Mode Switch 'A' Circuit Shorted?

- It is not recommended to drive your vehicle with this code present, as it can lead to further damage to the transmission system. It's best to address the issue promptly.

5. Is it possible to repair the Internal Mode Switch 'A' Circuit Shorted code P18B5 in a Chevrolet myself?

- While some DIY enthusiasts may attempt to repair this issue, it is recommended to seek professional help, especially when dealing with transmission-related problems to ensure proper diagnosis and repair.

6. How much does it typically cost to repair the OBDII code P18B5 in a Chevrolet due to the Internal Mode Switch 'A' Circuit Shorted?

- The cost of repair can vary depending on the extent of the damage and whether you choose to go to a dealership or an independent mechanic. It's best to get quotes from different sources.

7. Can resetting the OBDII code P18B5 in a Chevrolet fix the issue temporarily?

- Resetting the code may temporarily clear the warning light, but if the underlying issue causing the code is not addressed, it is likely to reappear. It's important to diagnose and fix the root cause.

8. Are there any preventive maintenance tips to avoid encountering the Internal Mode Switch 'A' Circuit Shorted code P18B5 in a Chevrolet?

- Regularly inspecting the transmission system, ensuring proper wiring connections, and addressing any warning signs promptly can help prevent issues like the P18B5 code.

9. Will the OBDII code P18B5 Internal Mode Switch 'A' Circuit Shorted affect the overall performance of my Chevrolet?

- Yes, this code can impact the transmission performance of your vehicle, leading to issues with shifting gears and potentially causing further damage if not addressed promptly.

10. How long does it take to repair the Internal Mode Switch 'A' Circuit Shorted code P18B5 in a Chevrolet?

- The repair time can vary depending on the exact cause of the issue and the availability of parts. It's best to consult with a professional mechanic for a more accurate estimate.