CLAAS 7893h – EXT (A62): Invalid Signal from Right Stop Light

The external function module (EXT) is not receiving valid information from the right stop light, or has not received any information for more than 5 seconds via the CAN bus. This indicates either a complete loss of signal or the reception of an invalid signal, preventing proper operation of the right stop light.

• Axion 810
• Axion 820
• Axion 830
• Axion 840
• Axion 850
• Arion 510
• Arion 520
• Arion 530
• Arion 540
• Arion 610
• Arion 620
• Arion 630
• Arion 640

1. 1

   Visually inspect the right stop light for physical damage, such as a broken lens or housing.

2. 2

   Check the wiring leading to the light for any signs of chafing, cuts, or corrosion.

3. 3

   Remove and inspect the stop light bulb filament; test for continuity across the bulb's terminals if the filament appears intact.

4. 4

   Verify power supply by checking for battery voltage at the right stop light connector with the ignition on and the brake pedal pressed.

5. 5

   Inspect the earth/ground connection for the stop light to ensure it is clean, tight, and free of corrosion.

6. 6

   Visually inspect the CAN bus wiring harness for damage and check connectors for moisture ingress.

7. 7

   Test CAN bus termination resistance (should be approximately 60 Ω with system powered off).

8. 8

   Check CAN bus voltage levels with the system powered on (CAN_H should be 2.5V-3.5V; CAN_L should be 1.5V-2.5V).

1. 1

   Address Simple Faults First

   If a faulty bulb, poor connection, or damaged wiring is found during the diagnostic checks, rectify these issues first. This may be sufficient to clear the fault code.

2. 2

   Isolate the Faulty Component

   If the basic checks do not resolve the issue, the problem likely lies with the stop light assembly itself, the EXT (A62) module, or the CAN bus wiring between them.

3. 3

   Check the Stop Light Assembly

   If possible, test the stop light assembly with a direct power source to confirm its functionality. If it fails to illuminate, the assembly itself is likely faulty and requires replacement.

4. 4

   Troubleshoot the EXT (A62) Module

   If the module is suspected to be faulty, it is recommended to consult a CLAAS service technician, as replacement may require programming.

5. 5

   CAN Bus Repair

   If a fault is identified in the CAN bus wiring (e.g., a break or short circuit), the damaged section of the harness will need to be repaired or replaced. This is a complex task that should ideally be performed by a qualified technician to ensure the integrity of the network.

6. 6

   Clear Fault Codes

   After performing any repairs, clear the fault codes using a compatible diagnostic tool and test the stop light functionality to ensure the issue is resolved.