AutoCodes – GMC – U0181 GMC

U0181 GMC Code - Lost Communication With Headlamp Leveling Control Module

Quick Answer

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Headlamp Leveling Control Module, Headlamp Leveling Control Module harness is open or shorted, Headlamp Leveling Control Module 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: U0181 GMC indicates Lost Communication With Headlamp Leveling Control Module.
Common causes: Common causes include Faulty Headlamp Leveling Control Module, Headlamp Leveling Control Module harness is open or shorted, Headlamp Leveling Control Module 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 3,356

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 Apr 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code U0181 GMC Description

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Headlamp Leveling Control Module has not been received.

OBDII Code U0181 GMC - Lost Communication With Headlamp Leveling Control Module - AutoCodes.com — U0181 GMC Code - Lost Communication With Headlamp Leveling Control Module

What does this mean?

What are the Possible Causes of the DTC U0181 GMC?

Faulty Headlamp Leveling Control Module
Headlamp Leveling Control Module harness is open or shorted
Headlamp Leveling Control Module circuit poor electrical connection

How to Fix the DTC U0181 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 U0181 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.