AutoCodes – Generic – B0285

B0285 Code - Electric Rear Defrost Circuit Low

Quick Answer

The Liftgate Module (LGM) monitors the voltage level on the supply voltage circuit of the rear window defogger. Common causes include Faulty Liftgate Module (LGM), Liftgate Module (LGM) harness is open or shorted, Liftgate Module (LGM) circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B0285 indicates Electric Rear Defrost Circuit Low.
Common causes: Common causes include Faulty Liftgate Module (LGM), Liftgate Module (LGM) harness is open or shorted, Liftgate Module (LGM) circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 1,123

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 10, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0285 Description

The Liftgate Module (LGM) monitors the voltage level on the supply voltage circuit of the rear window defogger. The LGM test the supply voltage circuit of the rear window defogger every 160 milliseconds. With the rear window defogger inactive, the supply voltage circuit of the rear window defogger will have no voltage present. With the rear window defogger active, the supply voltage circuit of the rear window defogger will be near system voltage.

OBDII Code B0285 - Electric Rear Defrost Circuit Low - AutoCodes.com — B0285 Code - Electric Rear Defrost Circuit Low

What does this mean?

What are the Possible Causes of the DTC B0285?

Faulty Liftgate Module (LGM)
Liftgate Module (LGM) harness is open or shorted
Liftgate Module (LGM) circuit poor electrical connection

How to Fix the DTC B0285?

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 B0285 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.

Need more information about the B0285 code?

Need more information on how to fix the B0285 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B0285 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B0285 Buick — Electric Rear Defrost Circuit Low
B0285 Cadillac — Electric Rear Defrost Circuit Low
B0285 Chevrolet — Electric Rear Defrost Circuit Low
B0285 GMC — Electric Rear Defrost Circuit Low

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 B0285 Code

1. What are the common symptoms of OBDII code B0285 (Electric Rear Defrost Circuit Low)?

Common symptoms include the rear defroster not working, a rear window that remains foggy or frosted, and possibly a check engine light or warning message on the dashboard.

2. What are the possible causes of OBDII code B0285?

Potential causes include a damaged defroster grid or connections, a faulty rear defrost switch, a blown fuse, or a problem with the rear defrost relay or module.

3. How can I diagnose the Electric Rear Defrost Circuit Low code B0285?

You can start by visually inspecting the rear defroster grid and connections for any damage. Use a multimeter to test the continuity of the grid and check the rear defrost switch, fuse, relay, and module for proper functioning.

4. Can I repair OBDII code B0285 myself?

If you have experience with automotive electrical systems and the necessary tools, you may be able to repair the issue yourself. However, if you're unsure, it's best to consult a professional mechanic for an accurate diagnosis and proper repair.

5. What are some tips for fixing the Electric Rear Defrost Circuit Low error code?

Ensure all connections to the rear defroster are secure and free of corrosion. Replace any damaged grid lines, blown fuses, or faulty components such as switches, relays, or modules to resolve the issue.

6. Is it safe to drive with the Electric Rear Defrost Circuit Low code activated?

While it is generally safe to drive with this code, having a non-functioning rear defroster can impair visibility in cold or humid conditions. It's recommended to address the issue promptly, especially in inclement weather.

7. Will resetting the OBDII code B0285 make the problem go away?

Resetting the code may temporarily clear the error, but if the underlying issue causing the Electric Rear Defrost Circuit Low code is not fixed, the check engine light will likely reappear once the system detects the problem again.

8. How much does it typically cost to repair OBDII code B0285 at a repair shop?

The cost of repairing this code can vary depending on the exact cause of the issue and the labor rates of the repair shop. Costs may range from a simple fuse replacement to more complex repairs involving components like the defrost module.

9. Can extreme weather conditions trigger the Electric Rear Defrost Circuit Low code?

Yes, extreme weather conditions like frost, ice, or heavy rain can sometimes trigger this code if they cause damage to the rear defroster grid or affect the electrical connections in the system.

10. Is OBDII code B0285 specific to certain vehicle makes and models?

While this code is related to the electric rear defrost circuit, it can be found in various vehicle makes and models that are equipped with a rear window defroster system.