how to troubleshoot the CAN bus communication error in my BMW 5 Series F10/F11 (2010-2017)

BMW 5 Series F10/F11 (2010-2017)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

560 words

Problem Statement

The vehicle is experiencing a CAN bus communication error, which affects the communication between various electronic control units (ECUs) in the BMW 5 Series F10/F11 (2010-2017).

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect the battery before working on any electrical components to prevent shocks or shorts.
•Ensure the vehicle is off and cool before inspecting the wiring harness.

Symptoms

•Warning lights illuminated on the dashboard
•Inoperative or malfunctioning features (e.g., power windows, door locks, infotainment system)
•Faulty readings from gauges (e.g., speedometer, fuel gauge)
•Communication errors reported by diagnostic scanner
•Random resets or shutdowns of electronic systems

Diagnostic Steps

1
Scan the vehicle using an OBD-II scanner to check for any stored error codes related to the CAN bus.
2
Inspect the CAN bus wiring harness for any visible damage, such as fraying, corrosion, or loose connections.
3
Check the battery voltage and ground connections to ensure proper power supply to the ECUs.
4
Use a multimeter to measure the resistance on the CAN bus lines (CAN High and CAN Low).
5
Disconnect and inspect each ECU connected to the CAN bus for signs of damage or corrosion.
6
Check the termination resistors at both ends of the CAN bus for proper resistance (typically 120 ohms).
7
Perform a visual inspection of fuses related to the CAN bus and replace any blown fuses.

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

•OBD-II scanner
•Multimeter
•Electrical contact cleaner
•Socket set
•Torque wrench (if required for ECU mounting)

Parts Required

•Termination resistors (120 ohms)
•Replacement wiring or connectors (if damaged)

Related Faults

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Symptoms

•Warning lights illuminated on the dashboard

•Inoperative or malfunctioning features (e.g., power windows, door locks, infotainment system)

•Faulty readings from gauges (e.g., speedometer, fuel gauge)

•Communication errors reported by diagnostic scanner

•Random resets or shutdowns of electronic systems

Diagnostic Steps

1
Scan the vehicle using an OBD-II scanner to check for any stored error codes related to the CAN bus.
2
Inspect the CAN bus wiring harness for any visible damage, such as fraying, corrosion, or loose connections.
3
Check the battery voltage and ground connections to ensure proper power supply to the ECUs.
4
Use a multimeter to measure the resistance on the CAN bus lines (CAN High and CAN Low).
5
Disconnect and inspect each ECU connected to the CAN bus for signs of damage or corrosion.
6
Check the termination resistors at both ends of the CAN bus for proper resistance (typically 120 ohms).
7
Perform a visual inspection of fuses related to the CAN bus and replace any blown fuses.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked on a level surface with the ignition off.
Disconnect the vehicle battery to prevent electrical shorts.

2. Inspect Wiring Harness

Remove any protective covers or insulation on the CAN bus wiring harness.
Check for physical damage, corrosion, or loose connections.
Repair any damaged wires and ensure all connectors are secure.

3. Test ECUs

Reconnect the vehicle battery.
Use an OBD-II scanner to access each ECU's communication status.
If an ECU is unresponsive, remove it and inspect for physical damage or corrosion on the pins.
Clean the connectors with electrical contact cleaner if necessary.

4. Replace Termination Resistors

Locate the termination resistors at the ends of the CAN bus.
Measure the resistance of each resistor to confirm they are functioning properly.
If a resistor is faulty, replace it with a new 120-ohm resistor.

5. Recheck Communication

Reconnect the vehicle battery.
Use the OBD-II scanner to check for communication errors again.
Clear any stored codes and verify that the issue has been resolved.