how to fix the rear defroster not working on BMW 5 Series F10/F11 (2010-2017)

BMW 5 Series F10/F11 (2010-2017)

Error Codes

1-2 hours

Time

medium

Difficulty

medium

Severity

3 min read

563 words

Problem Statement

The rear defroster on a BMW 5 Series F10/F11 (2010-2017) is not functioning, preventing effective clearing of the rear windshield during cold or inclement weather.

Estimated Time

1-2 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems.
•Ensure the vehicle is in a secure position and away from any moving parts.

Symptoms

•Rear defroster switch does not light up when activated
•No heat or clearing effect on the rear windshield
•Possible blown fuse related to the rear defroster circuit
•Visual inspection shows intact defroster grid lines with no breaks
•Error messages regarding the heating system on the dashboard (if applicable)

Diagnostic Steps

1
Check the rear defroster switch for proper operation and illumination.
2
Inspect the fuses in the glove compartment fuse box for any blown fuses related to the rear defroster.
3
Use a multimeter to test continuity of the defroster grid lines on the rear windshield.
4
Verify power supply to the rear defroster relay using a wiring diagram.
5
Inspect the rear defroster relay for proper function by swapping it with a similar relay in the fuse box (if applicable).

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Multimeter
•Fuse puller
•Pliers
•Defroster repair kit (if needed)

Parts Required

•Replacement fuse (if applicable)
•Rear defroster relay (if applicable)
•Defroster grid repair kit (if needed)

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Symptoms

•Rear defroster switch does not light up when activated

•No heat or clearing effect on the rear windshield

•Possible blown fuse related to the rear defroster circuit

•Visual inspection shows intact defroster grid lines with no breaks

•Error messages regarding the heating system on the dashboard (if applicable)

Diagnostic Steps

1
Check the rear defroster switch for proper operation and illumination.
2
Inspect the fuses in the glove compartment fuse box for any blown fuses related to the rear defroster.
3
Use a multimeter to test continuity of the defroster grid lines on the rear windshield.
4
Verify power supply to the rear defroster relay using a wiring diagram.
5
Inspect the rear defroster relay for proper function by swapping it with a similar relay in the fuse box (if applicable).

Solution

1. Preparation

Gather tools and parts needed for the repair.
Disconnect the vehicle's battery to ensure safety while working on electrical components.

2. Check and Replace Fuse

Locate the fuse box in the glove compartment.
Remove the cover and identify the fuse related to the rear defroster (refer to the fuse diagram).
Pull the fuse using a fuse puller or pliers and inspect it for continuity.
- If blown, replace it with a fuse of the same amperage.
Reinstall the fuse cover and reconnect the battery.

3. Test and Replace Rear Defroster Relay

Identify the rear defroster relay in the fuse box using the relay diagram.
Remove the relay and visually inspect it for any damage.
If a similar relay is available, swap it to test functionality.
If the relay is faulty, replace it with a new relay of the same specifications.

4. Repair Defroster Grid Lines (if necessary)

If continuity tests show breaks in the defroster grid lines, purchase a defroster repair kit.
Follow the instructions on the kit to apply conductive paint or repair solution to the damaged areas of the grid.
Allow the repair to cure as per the kit instructions before testing.

5. Reassemble and Test

Reconnect the battery.
Turn on the vehicle and activate the rear defroster.
Monitor for proper operation and heat generation on the rear windshield.