CLAAS Id78D0h / 78D0h (872) – REH (A58) - Rear Lifting Module: Communication loss between lifting module REH (A58) and external function module EXT (A62)

The lifting module REH (A58) has detected a communication loss with the external function module EXT (A62) during a CSM (CLAAS Sequence Management) sequence. The rear lifting function is disconnected and becomes inoperative. The tractor will attempt to initialize after 20 seconds and relaunch the sequence.

• CLAAS Axion 800 Series (810, 850)
• CLAAS Axion 900 Series (920, 950)
• CLAAS Arion 600 Series (610, 630, 640)
• CLAAS Arion 500 Series (510)

1. 1

   Verify the status of the lifting module REH (A58) and the external function module EXT (A62)

2. 2

   Check the connectors and the continuity of the wiring harnesses linking the REH (A58) and EXT (A62) modules on the CLAAS vehicle CAN bus

3. 3

   Check for any short-circuits or open circuits in the communication lines

4. 4

   Check the sources of energy (fuses, power supply, and ground) for both the A58 and A62 modules

5. 5

   Check the compatibility of program versions, settings, and calibration between the modules

1. 1

   System Reset

   Wait to see if the sequence relaunches after the 20-second auto-initialization. If nothing happens, manually reset the CSM (CLAAS Sequence Management).

2. 2

   Visual Inspection

   Inspect the wiring harness and connectors at both the REH (A58) module (typically located under the right-hand console) and the EXT (A62) module. Look for pushed pins, corrosion, or wire chafing.

3. 3

   Electrical Testing

   Using a multimeter, test the CAN bus communication lines between the REH and EXT modules for continuity, short-to-ground, and short-to-power.

4. 4

   Verify Power/Ground

   Ensure both modules are receiving stable 12V power and have a clean ground connection.

5. 5

   Repair Wiring

   Repair any damaged wiring or replace faulty connector pins discovered during testing.

6. 6

   Module Replacement

   If the wiring, power, and grounds are completely intact and the CSM reset does not restore communication, one of the modules (REH or EXT) has suffered an internal failure and must be replaced. (Note: Replacement modules will require dealer programming/calibration to match the tractor's software version).