CLAAS 76F7h – BDG (A103): No Message Received from WLP(A104)

The BDG (A103) CAN network communication module has not received a message from the WLP (A104) working light module for at least five seconds. This communication breakdown on the vehicle's CAN bus causes the working light module and its associated functions to become inactive. The issue typically stems from a CAN bus wiring fault, a failure within the working light module itself, or a failure in the central communication module.

• Arion 640-510
• Axion 800-850

1. 1

   Note all present error codes, as other faults may trigger this communication error

2. 2

   With vehicle power off, measure resistance between the CAN-H and CAN-L lines (expected: ~60 Ohms; 120 Ohms indicates a missing terminating resistor or wiring break)

3. 3

   Check for short circuits between the CAN lines and to the vehicle's chassis (ground) or power supply

4. 4

   Visually inspect the CAN bus wiring harness and connectors for chafing, corrosion, or loose connections

5. 5

   Inspect the WLP (A104) module connectors and verify it is receiving power and has a solid ground connection

6. 6

   Inspect the BDG (A103) module connectors and its connection to the CAN bus

1. 1

   Isolate the CAN bus fault

   If CAN bus resistance is incorrect (e.g., 120 Ohms), disconnect modules one by one and re-measure resistance until it returns to 60 Ohms to isolate the faulty network section.

2. 2

   Repair wiring harness

   Repair or replace any identified open circuits, short circuits, or corroded sections in the CAN wiring harness. Ensure all connections are clean and secure.

3. 3

   Replace WLP (A104) module

   If wiring and connections are good, the WLP module likely has an internal failure (e.g., faulty transistors, cold solder joints, or corrosion). Replace the module.

4. 4

   Replace BDG (A103) module

   If the WLP module is replaced, the CAN network is intact, and the fault persists, replace the BDG (A103) module.

5. 5

   Program new modules

   Use the CLAAS Diagnostic System (CDS) to program and configure any replaced modules so they function correctly with the specific tractor.