AutoCodes – Mercury – U0199 Mercury

U0199 Mercury Code - Lost Communication With Door Control Module 'A'

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Door Control Module 'A', Door Control Module 'A' harness is open or shorted, Door Control Module 'A' 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: U0199 Mercury indicates Lost Communication With Door Control Module 'A'.
Common causes: Common causes include Faulty Door Control Module 'A', Door Control Module 'A' harness is open or shorted, Door Control Module 'A' 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 515

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 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0199 Mercury Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Door Control Module 'A' has not been received.

OBDII Code U0199 Mercury - Lost Communication With Door Control Module 'A' - AutoCodes.com — U0199 Mercury Code - Lost Communication With Door Control Module 'A'

What does this mean?

What are the Possible Causes of the DTC U0199 Mercury?

Faulty Door Control Module 'A'
Door Control Module 'A' harness is open or shorted
Door Control Module 'A' circuit poor electrical connection

How to Fix the DTC U0199 Mercury?

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 U0199 Mercury 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 U0199 Mercury Code

1. What does the OBDII code U0199 mean on a Mercury?

U0199 indicates that the vehicle's main computer has lost communication with Door Control Module 'A' (DCM-A), which manages functions like door locks and windows.

2. What are the common symptoms of the U0199 code?

Common symptoms include non-functioning power door locks, unresponsive power windows, intermittent interior lighting, or a door ajar warning on the dashboard.

3. What causes the U0199 code to appear?

Possible causes include a faulty Door Control Module 'A,' damaged wiring or connectors in the communication circuit, a blown fuse, or a low or weak vehicle battery.

4. Can a weak car battery trigger the U0199 code?

Yes, a low or weak battery can cause communication issues between modules, potentially triggering the U0199 code.

5. How can I diagnose the U0199 code?

Start by checking the battery voltage, inspecting the wiring and connectors for damage, and using a scan tool to verify communication with the Door Control Module 'A.'

6. Is it safe to drive with the U0199 code present?

While it may not immediately affect drivability, safety features like power door locks and windows might not function properly, which could be a concern in certain situations.

7. How do I fix the U0199 code on a Mercury?

Repairs may involve replacing the Door Control Module 'A,' repairing damaged wiring or connectors, resetting the system with a scan tool, or addressing battery or fuse issues.

8. Do I need to replace the Door Control Module 'A' to fix the U0199 code?

Not always. First, check for damaged wiring, loose connections, or blown fuses, as these issues can often resolve the problem without replacing the module.

9. Can the U0199 code reset itself?

In some cases, the code may reset itself after addressing the underlying issue, such as fixing a loose connection or replacing a blown fuse. However, a scan tool may be required to clear the code.

10. What tools are needed to troubleshoot the U0199 code?

You'll need a scan tool capable of reading manufacturer-specific codes, a multimeter for testing voltage and continuity, and basic tools to inspect wiring and connectors.