AutoCodes – GMC – P181C GMC

P181C GMC Code - Internal Mode Switch 2 R1 Circuit Low Voltage

Quick Answer

The automatic transmission manual shift shaft position switch assembly, also called the internal mode switch assembly, contains two sliding hall-effect switch assemblies attached to the control valve body within the transmission. Common causes include Faulty Manual Shift Shaft Position Switch Assembly, Manual Shift Shaft Position Switch Assembly harness is open or shorted, Manual Shift Shaft Position Switch Assembly 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: P181C GMC indicates Internal Mode Switch 2 R1 Circuit Low Voltage .
Common causes: Common causes include Faulty Manual Shift Shaft Position Switch Assembly, Manual Shift Shaft Position Switch Assembly harness is open or shorted, Manual Shift Shaft Position Switch Assembly 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 920

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 Jan 30, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P181C GMC Description

The automatic transmission manual shift shaft position switch assembly, also called the internal mode switch assembly, contains two sliding hall-effect switch assemblies attached to the control valve body within the transmission. The 9 outputs from the switches indicate which position is selected by the transmission manual shaft. Four outputs (A, B, C, P) are range selection inputs to the transmission control module (TCM). Five outputs (R1, R2, D1, D2, S) are direction selection inputs to the hybrid powertrain control module. The Range input signals are represented as TCM scan tool parameters, Internal Mode Switch A, B, C, and P. The Direction input signals are represented as hybrid powertrain control module scan tool parameters, Internal Mode Switch 2 - R1, R2, D1, D2, and S. The input voltage at the modules is high when a switch is open and low when a switch is closed to earth. Each control module independently supplies power and earth to its respective switch assembly.
The hybrid powertrain control module is internal to the power inverter module, often referred to as the drive motor generator power inverter module and is not serviced separately.

OBDII Code P181C GMC - Internal Mode Switch 2 R1 Circuit Low Voltage - AutoCodes.com — P181C GMC Code - Internal Mode Switch 2 R1 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P181C GMC?

Faulty Manual Shift Shaft Position Switch Assembly
Manual Shift Shaft Position Switch Assembly harness is open or shorted
Manual Shift Shaft Position Switch Assembly circuit poor electrical connection

How to Fix the DTC P181C GMC?

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 P181C GMC 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.

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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 P181C GMC Code

1. What are the common symptoms of OBDII code P181C GMC (Internal Mode Switch 2 R1 Circuit Low Voltage)?

The common symptoms include issues with shifting gears, hesitation or jerking when accelerating, and the inability to shift out of a certain gear.

2. What are the possible causes of OBDII code P181C GMC?

Possible causes of this code include a faulty internal mode switch, damaged wiring or connectors in the circuit, or a malfunctioning transmission control module.

3. How can I diagnose OBDII code P181C GMC?

Diagnosing this code involves using a diagnostic scanner to retrieve the trouble codes, checking for any visible damage to wiring or connectors, and performing a thorough inspection of the internal mode switch.

4. Can driving with OBDII code P181C GMC cause further damage to my vehicle?

Continuing to drive with this code may potentially cause further damage to the transmission system over time, so it is recommended to address the issue promptly.

5. Is it safe to continue driving my vehicle with OBDII code P181C GMC?

It is not recommended to continue driving your vehicle with this code as it may lead to unsafe driving conditions and potential transmission issues.

6. How can I repair OBDII code P181C GMC?

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

7. Can I reset OBDII code P181C GMC without fixing the underlying issue?

Resetting the code without addressing the underlying issue will only temporarily clear the code, and the problem is likely to reoccur.

8. How much does it typically cost to repair OBDII code P181C GMC?

The cost of repairing this code can vary depending on the specific cause of the issue, but it may range from a few hundred to a thousand dollars, including parts and labor.

9. Are there any preventative measures I can take to avoid OBDII code P181C GMC in the future?

Regularly maintaining your vehicle, checking for any signs of transmission issues, and addressing any problems promptly can help prevent this code from occurring in the future.

10. Can a DIY enthusiast with basic automotive knowledge repair OBDII code P181C GMC?

While some repairs related to this code may be feasible for a DIY enthusiast, diagnosing and repairing transmission issues can be complex and may require specialized tools and expertise, so it is recommended to consult a professional mechanic.