AutoCodes – GMC – P18C5 GMC

P18C5 GMC Code - Gear Position Sensor Circuit 1 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: P18C5 GMC indicates Gear Position Sensor Circuit 1 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 833

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 P18C5 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 radial position signal 1 circuit for low and high voltage conditions.

OBDII Code P18C5 GMC - Gear Position Sensor Circuit 1 High Voltage - AutoCodes.com — P18C5 GMC Code - Gear Position Sensor Circuit 1 High Voltage

What does this mean?

What are the Possible Causes of the DTC P18C5 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 P18C5 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 P18C5 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 P18C5 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 P18C5 GMC Code

1. What are the common symptoms of OBDII code P18C5 GMC (Gear Position Sensor Circuit 1 High Voltage)?

- Common symptoms include erratic shifting behavior, difficulty shifting gears, and the transmission getting stuck in a specific gear.

2. What causes OBDII code P18C5 GMC to trigger?

- This code is typically triggered by a malfunction in the gear position sensor circuit, such as a short circuit, open circuit, or high voltage reading.

3. How serious is OBDII code P18C5 GMC?

- This code can cause drivability issues and affect the performance of the transmission, so it is important to address it promptly to avoid further damage.

4. Can driving with OBDII code P18C5 GMC cause damage to the vehicle?

- Continued driving with this code can potentially cause damage to the transmission or other related components, so it is best to address the issue as soon as possible.

5. What are some DIY repair tips for OBDII code P18C5 GMC?

- DIY repair tips may include checking the wiring and connectors related to the gear position sensor, performing a visual inspection for any visible damage, and testing the sensor's voltage output.

6. How is OBDII code P18C5 GMC diagnosed?

- Diagnosing this code typically involves using an OBDII scanner to retrieve the code, checking the transmission fluid level, inspecting the gear position sensor circuit, and testing the sensor for proper operation.

7. Is it safe to continue driving with OBDII code P18C5 GMC?

- It is not recommended to continue driving with this code as it can lead to potential transmission issues and safety concerns on the road.

8. Can a faulty gear position sensor cause OBDII code P18C5 GMC to appear?

- Yes, a faulty gear position sensor or issues within its circuit can trigger this specific OBDII code related to high voltage readings.

9. How much does it typically cost to repair OBDII code P18C5 GMC?

- The cost of repairing this code can vary depending on the exact cause of the issue, but it may involve replacing the gear position sensor, repairing wiring, or addressing other related components.

10. How long does it take to repair OBDII code P18C5 GMC?

- The repair time for this code can vary based on the extent of the issue and the repair process needed, but it may take a few hours to a full day for diagnosis and repair.