AutoCodes – GMC – P18C6 GMC

P18C6 GMC Code - Gear Position Sensor Circuit 2 Low 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: P18C6 GMC indicates Gear Position Sensor Circuit 2 Low 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 1,078

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 P18C6 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 P18C6 GMC - Gear Position Sensor Circuit 2 Low Voltage - AutoCodes.com — P18C6 GMC Code - Gear Position Sensor Circuit 2 Low Voltage

What does this mean?

What are the Possible Causes of the DTC P18C6 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 P18C6 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 P18C6 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 P18C6 GMC Code

1. What are the common symptoms of OBDII code P18C6 GMC (Gear Position Sensor Circuit 2 Low Voltage)?

- Common symptoms include incorrect gear display on the dashboard, issues with shifting gears, and possible limp mode activation.

2. What are the possible causes of the P18C6 GMC trouble code?

- The code P18C6 GMC can be triggered by a faulty gear position sensor, damaged wiring or connectors in the sensor circuit, or a malfunctioning transmission control module (TCM).

3. How serious is the P18C6 GMC trouble code?

- While the vehicle may still be operable with this code, it is important to address it promptly to avoid potential transmission issues and ensure proper gear shifting.

4. Can I continue driving my vehicle with the P18C6 GMC trouble code?

- It is not recommended to drive the vehicle with the P18C6 GMC trouble code present, as it can lead to further damage to the transmission or drivability issues.

5. How can I diagnose the P18C6 GMC trouble code?

- Diagnosing the P18C6 GMC trouble code involves using a scan tool to retrieve the code, inspecting the gear position sensor and its wiring, and testing the TCM for proper function.

6. What are some repair tips for fixing the P18C6 GMC trouble code?

- Repair tips may include replacing the gear position sensor, repairing any damaged wiring or connectors, or reprogramming the TCM to resolve the low voltage issue.

7. How much does it typically cost to repair the P18C6 GMC trouble code?

- The cost of repairing the P18C6 GMC trouble code can vary depending on the specific issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Can I reset the P18C6 GMC trouble code without fixing the underlying issue?

- While clearing the trouble code may temporarily turn off the check engine light, it is essential to address the root cause of the problem to prevent it from reoccurring.

9. Will the P18C6 GMC trouble code cause my vehicle to fail an emissions test?

- Yes, the P18C6 GMC trouble code can cause your vehicle to fail an emissions test due to its impact on proper transmission operation and gear shifting.

10. How long does it take to repair the P18C6 GMC trouble code?

- The repair time for the P18C6 GMC trouble code can vary based on the specific issue and the mechanic's expertise, but it may take a few hours to a full day to diagnose and fix the problem thoroughly.