U1021 Mercury Code - Lost Communication With Anti-Lock Brake System Control Module
Quick Answer
The Diagnostic Trouble Code (DTC) sets in the Powertrain Control Module (PCM) if data messages received from the Anti-Lock Brake System (ABS) Control Module over the HS-CAN2 is missing. Common causes include Faulty Anti-Lock Brake System (ABS) Control Module, Anti-Lock Brake System Control Module harness is open or shorted, Anti-Lock Brake System 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
- U1021 Mercury indicates Lost Communication With Anti-Lock Brake System Control Module.
- Common causes
- Common causes include Faulty Anti-Lock Brake System (ABS) Control Module, Anti-Lock Brake System Control Module harness is open or shorted, Anti-Lock Brake System 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.
Code U1021 Mercury Description
What are the Possible Causes of the DTC U1021 Mercury?
- Faulty Anti-Lock Brake System (ABS) Control Module
- Anti-Lock Brake System Control Module harness is open or shorted
- Anti-Lock Brake System Control Module circuit poor electrical connection
- Faulty Powertrain Control Module (PCM)
How to Fix the DTC U1021 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 U1021 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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Frequently Asked Questions about U1021 Mercury Code
1. What does the OBDII code U1021 mean for a Mercury?
The U1021 code indicates that the vehicle has lost communication with the Anti-Lock Brake System (ABS) control module.
2. What are the common symptoms of the U1021 code?
Symptoms may include the ABS warning light or check engine light turning on, reduced braking performance, or intermittent ABS functionality.
3. What causes the U1021 code to appear?
Common causes include a faulty ABS control module, damaged wiring or connectors, a blown fuse, or a problem with the vehicle's communication network.
4. Can I still drive my Mercury with the U1021 code?
While the vehicle may still be drivable, the ABS may not function properly, which could result in reduced braking performance, especially in slippery conditions.
5. How do I diagnose the U1021 code?
Start by inspecting the ABS control module, wiring, and connectors for damage or corrosion. Use a scan tool to check for additional communication-related codes.
6. What are common fixes for the U1021 code?
Repairs may include replacing the ABS control module, repairing or replacing damaged wiring, cleaning corroded connectors, or replacing a blown fuse.
7. Can a low battery cause the U1021 code?
Yes, a weak or failing battery can disrupt communication between modules and trigger the U1021 code.
8. How much does it cost to fix the U1021 code?
Repair costs vary depending on the issue. Replacing an ABS control module can cost $300–$1,000, while fixing wiring or connectors may cost less.
9. Can a software update fix the U1021 code?
In some cases, a software update for the ABS or related modules may resolve communication issues. Consult your Mercury dealership for details.
10. Is the U1021 code specific to Mercury vehicles?
No, the U1021 code is a generic communication fault code, but its diagnosis and repair may vary depending on the make and model of the vehicle.
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