AutoCodes – GMC – U1728 GMC

U1728 GMC Code - Left Headlamp High Beam Control Module Lost Communication With Left Headlamp Leveling Actuator

Quick Answer

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. Common causes include Faulty Left Headlamp Leveling Actuator, Left Headlamp Leveling Actuator harness is open or shorted, Left Headlamp Leveling Actuator 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: U1728 GMC indicates Left Headlamp High Beam Control Module Lost Communication With Left Headlamp Leveling Actuator.
Common causes: Common causes include Faulty Left Headlamp Leveling Actuator, Left Headlamp Leveling Actuator harness is open or shorted, Left Headlamp Leveling Actuator 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 415

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 Jun 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code U1728 GMC Description

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. The serial data is transmitted over a LIN circuit between a master control module and other LIN devices within a particular subsystem. If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device. The Diagnostic Trouble Code (DTC) will set when a supervised periodic message to the Left Headlamp High Beam Control Module from the Left Headlamp Leveling Actuator has not been received.

OBDII Code U1728 GMC - Left Headlamp High Beam Control Module Lost Communication With Left Headlamp Leveling Actuator - AutoCodes.com — U1728 GMC Code - Left Headlamp High Beam Control Module Lost Communication With Left Headlamp Leveling Actuator

What does this mean?

What are the Possible Causes of the DTC U1728 GMC?

Faulty Left Headlamp Leveling Actuator
Left Headlamp Leveling Actuator harness is open or shorted
Left Headlamp Leveling Actuator circuit poor electrical connection
Faulty Left Headlamp High Beam Control Module

How to Fix the DTC U1728 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 U1728 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 U1728 GMC code?

Need more information on how to fix the U1728 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1728 GMC code diagnosed by a professional: Find a repair shop in your area

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 U1728 GMC Code

What does the OBDII code U1728 mean for my GMC vehicle?

The U1728 code indicates that there is a communication issue between the left headlamp high beam control module and the left headlamp leveling actuator.

What are the common symptoms of a U1728 code?

Common symptoms include malfunctioning left headlamp high beams, improper headlamp leveling, and dashboard warning lights related to headlamp operation.

What could cause the U1728 code to trigger?

Possible causes include damaged wiring or connectors, a faulty left headlamp leveling actuator, a malfunctioning headlamp control module, or issues with the vehicle's body control module.

How can I diagnose the U1728 code?

To diagnose the U1728 code, check for any visible damage to the wiring and connectors, use a scan tool to verify communication between modules, and test the left headlamp leveling actuator for proper operation.

What repairs are needed if my vehicle has a U1728 code?

Repairs may include repairing or replacing damaged wiring, replacing the left headlamp leveling actuator, or replacing the headlamp control module if it is found to be faulty.

Can I drive my vehicle safely with a U1728 code?

While the vehicle may be drivable, improper headlamp operation can reduce visibility, especially at night, making it unsafe to drive until the issue is resolved.

How can I clear the U1728 code after repairs?

You can clear the U1728 code using an OBDII scanner or by disconnecting the vehicle's battery for a short period, but ensure that the underlying issue is fixed first to prevent the code from returning.

Will a U1728 code affect my vehicleâ€™s inspection?

Yes, a U1728 code may cause your vehicle to fail an emissions or safety inspection, as it indicates a problem with the headlamp system.

Is the U1728 code specific to GMC vehicles?

While the U1728 code is commonly associated with GMC vehicles, it can also appear in other makes and models that use similar headlamp control systems.