AutoCodes - Generic - U1521

U1521 Code - Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3
Table of contents

|U1521 code possible causes

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

|How do I fix the U1521 code?

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|Cost of diagnosing the U1521 code

Labor: 1.0

The cost of diagnosing the U1521 code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|What are U1521 code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

|U1521 code 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 Headlamp Control Module/Headlamp Leveling Control Module from the Left Headlamp has not been received.
OBDII Code U1521 - Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus - AutoCodes.com

|Need more information with the U1521 code?

Need more information on how to fix the U1521 code?
Get Access to Factory Service Manuals

|U1521 code information for specific makes

  • U1521 BUICK Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus
  • U1521 CADILLAC Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus
  • U1521 CHEVROLET Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus
  • U1521 GMC Headlamp Control Module/Headlamp Leveling Control Module Lost Communication With Left Headlamp On LIN Bus

|Need help with a U1521 code?

Get the U1521 code diagnosed by a professional: Find a repair shop in your area

|U1521 code comments

Help us improve AutoCodes.com. Leave a comment below or tell us if the information above helps you fix the code. What are the symptoms on your vehicle for the U1521 code? Have you replaced any parts?
Any information is appreciated. Thanks
Top ⇧
Repair Importance Level: 3
 
1=Low 2=Medium 3=High What is this?
Repair Difficulty Level: 3
 
1=Easy 2=Moderate 3=Hard What is this?