AutoCodes – GMC – P181F GMC

P181F GMC Code - Internal Mode Switch 2 R2 Circuit High 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: P181F GMC indicates Internal Mode Switch 2 R2 Circuit High 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 872

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 P181F 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 P181F GMC - Internal Mode Switch 2 R2 Circuit High Voltage - AutoCodes.com — P181F GMC Code - Internal Mode Switch 2 R2 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P181F 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 P181F 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 P181F 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 P181F GMC Code

1. What are common symptoms of OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

The common symptoms include issues with shifting gears, hesitation when accelerating, and the transmission staying in one gear.

2. What are the possible causes of OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

Possible causes include a faulty internal mode switch, damaged wiring or connectors, low transmission fluid levels, or a malfunctioning transmission control module.

3. How can I diagnose OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

Diagnosis typically involves using a professional OBDII scanner to retrieve the code, checking the internal mode switch for proper operation, inspecting wiring and connectors for damage, and testing the transmission control module.

4. Can driving with OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage cause further damage?

Continuing to drive with this code can potentially cause damage to the transmission components and result in more severe transmission issues over time.

5. How can I repair OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

Repair options may include replacing the internal mode switch, repairing or replacing damaged wiring or connectors, ensuring proper transmission fluid levels, or reprogramming the transmission control module.

6. Is it safe to continue driving my vehicle with OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

It is not recommended to continue driving your vehicle with this code as it can lead to transmission problems and potential safety hazards on the road.

7. Can I reset OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage on my own?

While you can clear the code with an OBDII scanner, it is important to address the underlying issue causing the code to prevent it from recurring.

8. How much does it typically cost to repair OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

The cost of repair can vary depending on the exact cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

9. Are there any DIY steps I can take to troubleshoot OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

You can visually inspect wiring and connectors for damage, check transmission fluid levels, and ensure the internal mode switch is functioning properly. However, more in-depth diagnostics and repairs may require professional assistance.

10. How long does it typically take to repair OBDII code P181F GMC Internal Mode Switch 2 R2 Circuit High Voltage?

The repair time can vary depending on the exact cause of the issue and the complexity of the repair. It may take anywhere from a few hours to a full day to complete the necessary repairs.