AutoCodes – Cadillac – U2120 Cadillac

U2120 Cadillac Code - Lost Communication With Dynamic Headlamp Leveling Device

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Dynamic Headlamp Leveling (DHL) Device, Dynamic Headlamp Leveling Device harness is open or shorted, Dynamic Headlamp Leveling Device 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: U2120 Cadillac indicates Lost Communication With Dynamic Headlamp Leveling Device.
Common causes: Common causes include Faulty Dynamic Headlamp Leveling (DHL) Device, Dynamic Headlamp Leveling Device harness is open or shorted, Dynamic Headlamp Leveling Device 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 547

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 16, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U2120 Cadillac Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices 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 device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. A loss of serial data communications Diagnostic Trouble Code (DTC) does not represent a failure of the devices that contain the stored code. The DTC will set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U2120 Cadillac - Lost Communication With Dynamic Headlamp Leveling Device - AutoCodes.com — U2120 Cadillac Code - Lost Communication With Dynamic Headlamp Leveling Device

What does this mean?

What are the Possible Causes of the DTC U2120 Cadillac?

Faulty Dynamic Headlamp Leveling (DHL) Device
Dynamic Headlamp Leveling Device harness is open or shorted
Dynamic Headlamp Leveling Device circuit poor electrical connection

How to Fix the DTC U2120 Cadillac?

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 U2120 Cadillac 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.

Frequently Asked Questions about U2120 Cadillac Code

1. What are the common symptoms of OBDII code U2120 in a Cadillac related to the Dynamic Headlamp Leveling Device?

- Common symptoms include malfunctioning automatic headlight leveling, erratic headlight beam movement, or dashboard warning lights related to the headlamp system.

2. What are the possible causes of the U2120 code indicating a lost communication with the Dynamic Headlamp Leveling Device in a Cadillac?

- The code can be triggered by issues such as a faulty headlamp leveling sensor, damaged wiring harness, loose connections, or a malfunctioning control module.

3. How can I diagnose the U2120 OBDII code in a Cadillac experiencing communication loss with the Dynamic Headlamp Leveling Device?

- Diagnosis involves checking the headlamp leveling system components for physical damage, verifying wiring connections, and using a diagnostic scanner to read trouble codes and monitor sensor data.

4. What are some repair tips for resolving the U2120 code issue in a Cadillac?

- Repair tips include inspecting and repairing damaged wiring, replacing a faulty headlamp leveling sensor, ensuring all electrical connections are secure, and resetting the trouble code after repairs.

5. Can I drive my Cadillac with the U2120 code indicating lost communication with the Dynamic Headlamp Leveling Device?

- It is generally safe to drive the vehicle, but it is recommended to address the issue promptly to ensure proper functioning of the headlamp leveling system for optimal visibility and safety.

6. How much does it typically cost to repair the U2120 code related to the Dynamic Headlamp Leveling Device in a Cadillac?

- The cost of repairs can vary depending on the specific issue causing the communication loss, but it may range from $100 to $500 or more, including parts and labor.

7. Will disconnecting the battery reset the U2120 trouble code in a Cadillac?

- Disconnecting the battery may temporarily clear the trouble code, but it is recommended to diagnose and address the root cause of the issue to prevent the code from reoccurring.

8. Is the U2120 code specific to Cadillac vehicles, or can it occur in other car makes and models?

- While the U2120 code is specific to Cadillac vehicles, similar communication loss issues with headlamp leveling systems can occur in other car makes and models, triggering related OBDII codes.

9. How long does it typically take to repair the U2120 code related to the Dynamic Headlamp Leveling Device in a Cadillac?

- The repair time can vary based on the complexity of the issue and the availability of parts, but it may take anywhere from 1 to 4 hours to diagnose and fix the problem.

10. Can I reset the U2120 trouble code using an OBDII scanner, or is professional assistance required?

- An OBDII scanner can be used to reset the trouble code after repairs have been made to address the communication loss with the Dynamic Headlamp Leveling Device in a Cadillac.