AutoCodes – GMC – P18C7 GMC

P18C7 GMC Code - Gear Position Sensor Circuit 2 High Voltage

Quick Answer

The gear position sensor is a switching transistor mounted to the top of the transmission extension housing. Common causes include Faulty Gear Position Sensor, Gear Position Sensor harness is open or shorted, Gear Position Sensor 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: P18C7 GMC indicates Gear Position Sensor Circuit 2 High Voltage.
Common causes: Common causes include Faulty Gear Position Sensor, Gear Position Sensor harness is open or shorted, Gear Position Sensor 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 878

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 Feb 05, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P18C7 GMC Description

The gear position sensor is a switching transistor mounted to the top of the transmission extension housing. The four wire sensor interfaces directly with the Engine Control Module (ECM). The ECM supplies 5 V to the gear position sensor on a 5 V reference circuit and also provides a ground path on a low reference circuit. The sensor provides a Pulse Width Modulated (PWM) duty cycle to the ECM on two signal circuits that is proportional to the linear and radial position of the corresponding magnet assembly mounted to the shift shaft. The vehicle uses the gear position sensor information primarily for Active Rev Matching and Active Fuel Management. The ECM monitors the linear position signal 2 circuit for low and high voltage conditions.

OBDII Code P18C7 GMC - Gear Position Sensor Circuit 2 High Voltage - AutoCodes.com — P18C7 GMC Code - Gear Position Sensor Circuit 2 High Voltage

What does this mean?

What are the Possible Causes of the DTC P18C7 GMC?

Faulty Gear Position Sensor
Gear Position Sensor harness is open or shorted
Gear Position Sensor circuit poor electrical connection

How to Fix the DTC P18C7 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 P18C7 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.

Need more information about the P18C7 GMC code?

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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 P18C7 GMC Code

1. What are common symptoms of OBDII code P18C7 GMC (Gear Position Sensor Circuit 2 High Voltage)?

The common symptoms of this code may include issues with shifting gears, erratic gear changes, and the transmission going into limp mode.

2. What can cause the OBDII code P18C7 GMC to trigger?

This code is typically triggered by a faulty gear position sensor, damaged wiring or connectors in the gear position sensor circuit, or an issue with the transmission control module.

3. How can I diagnose the cause of OBDII code P18C7 GMC?

Diagnosing this code usually involves checking the gear position sensor and its wiring, inspecting for any damaged or loose connections, and using a scan tool to gather data from the transmission control module.

4. Can I continue driving my vehicle with OBDII code P18C7 GMC present?

It is not recommended to continue driving your vehicle with this code present, as it can lead to further transmission issues and potential safety hazards.

5. How can I repair OBDII code P18C7 GMC?

Repairing this code often involves replacing the faulty gear position sensor, repairing or replacing damaged wiring or connectors, and clearing the code from the vehicle's computer using a scan tool.

6. Is it possible for a DIY enthusiast to fix OBDII code P18C7 GMC?

While some experienced DIY enthusiasts may be able to diagnose and repair this code, it is generally recommended to seek professional help, especially when dealing with transmission-related issues.

7. How much does it typically cost to repair OBDII code P18C7 GMC at a mechanic or dealership?

The cost of repairing this code can vary depending on the extent of the issue, the labor rates of the service provider, and the cost of any replacement parts needed.

8. Can resetting the OBDII code P18C7 GMC temporarily fix the issue?

Resetting the code may temporarily clear the warning light, but it will not fix the underlying issue causing the code to trigger. It is important to address the root cause of the problem.

9. Are there any preventive maintenance steps to avoid OBDII code P18C7 GMC?

Regularly inspecting and maintaining the gear position sensor, checking for any signs of wear or damage in the wiring, and addressing any transmission-related issues promptly can help prevent this code from occurring.

10. How long does it typically take to repair OBDII code P18C7 GMC?

The repair time for this code can vary depending on the specific issue causing it and the expertise of the technician. In some cases, it can be resolved within a few hours, while more complex issues may take longer to diagnose and repair.