AutoCodes – GMC – P0502 GMC

P0502 GMC Code - Vehicle Speed Sensor Circuit Low Input

Quick Answer

The Vehicle Speed Sensor (VSS) assembly provides vehicle speed information to the Powertrain Control Module (PCM). Common causes include Faulty Vehicle Speed Sensor, Vehicle speed sensor harness or connectors is open or shorted, Vehicle speed 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: P0502 GMC indicates Vehicle Speed Sensor Circuit Low Input .
Common causes: Common causes include Faulty Vehicle Speed Sensor, Vehicle speed sensor harness or connectors is open or shorted, Vehicle speed 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 17,027

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0502 GMC Description

The Vehicle Speed Sensor (VSS) assembly provides vehicle speed information to the Powertrain Control Module (PCM). The VSS assembly is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage as rotor teeth on the transmission output shaft pass through the sensor's magnetic field. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The PCM converts the pulsing voltage to vehicle speed. The PCM uses the vehicle speed signal to determine shift timing and torque converter clutch (TCC) scheduling.

Vehicle Speed Sensor Location Example:

OBDII Code P0502 GMC - Vehicle Speed Sensor Circuit Low Input - AutoCodes.com — P0502 GMC Code - Vehicle Speed Sensor Circuit Low Input

What does this mean?

What are the Possible Causes of the DTC P0502 GMC?

Faulty Vehicle Speed Sensor
Vehicle speed sensor harness or connectors is open or shorted
Vehicle speed sensor circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P0502 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 P0502 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 P0502 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 P0502 GMC Code

1. What does the OBDII code P0502 on a GMC vehicle mean?

P0502 indicates a "Vehicle Speed Sensor Circuit Low Input," meaning the vehicle speed sensor is reporting a signal voltage that is too low.

2. What are the common symptoms of a P0502 code in a GMC vehicle?

Symptoms may include erratic or non-functional speedometer, poor transmission shifting, reduced engine performance, or activation of the check engine light.

3. What causes the P0502 code in GMC vehicles?

Common causes include a faulty vehicle speed sensor, damaged wiring or connectors, corrosion on electrical connections, or a malfunctioning PCM (Powertrain Control Module).

4. Can a P0502 code affect transmission performance in a GMC?

Yes, a faulty vehicle speed sensor can cause improper transmission shifting or hesitation due to inaccurate speed readings.

5. How can I diagnose the P0502 code in my GMC?

Inspect the vehicle speed sensor for damage, check the wiring and connectors for corrosion or loose connections, and use a multimeter to test the sensor voltage.

6. Can I still drive my GMC with a P0502 code?

While the vehicle may still be drivable, itâ€™s not recommended as improper speed readings can affect transmission function and overall driving safety.

7. How do I fix the P0502 code on my GMC?

Repairs may include replacing the vehicle speed sensor, repairing damaged wiring or connectors, or updating/reprogramming the PCM if necessary.

8. How much does it cost to fix the P0502 code on a GMC?

The repair cost can vary, but replacing a vehicle speed sensor typically ranges between $100 and $300, including parts and labor.

9. Can a faulty vehicle speed sensor trigger other codes besides P0502?

Yes, related codes like P0500 (Vehicle Speed Sensor Malfunction) or transmission-related codes may also appear.

10. Should I clear the P0502 code without repairing the issue on my GMC?

Clearing the code without addressing the underlying problem may result in the code returning and potential damage to the vehicleâ€™s transmission or engine systems.