CLAAS Id788Eh / 788Eh – EXT (A62) - External Function Module: CAN bus communication timeout related to the tractor's rear linkage

The external function module has not received the rear lifting position information for more than 5 seconds via the BUS CAN. The lifting position information is consequently not available over the 7-pin ISO connector.

• Axion 810
• Axion 820
• Axion 850
• Axion 920
• Axion 930
• Axion 940
• Axion 950
• Arion 510
• Arion 530
• Arion 550
• Arion 620
• Arion 640
• Arion 410
• Arion 430

1. 1

   Check the CLAAS vehicle CAN bus network for shorts to 12V, shorts to ground, or open circuits

2. 2

   Inspect the 7-Pin ISO Connector at the rear of the tractor for corrosion, water ingress, or pushed-out pins

3. 3

   Check the BDG (A103) CAN network communication module

4. 4

   Check the REH (A58) rear lifting module to ensure it is broadcasting lift position data

5. 5

   Check the EXT (A62) external function module for internal faults

1. 1

   Visual Inspection of the ISO Connector

   Start at the rear of the tractor. Inspect the 7-pin ISO connector. Clean out any dirt or corrosion. Ensure the wiring harness leading into the back of the socket is not frayed or damaged by implements.

2. 2

   Check for Cascading Fault Codes

   Connect the CLAAS Diagnostic System (CDS / METADIAG). Look for accompanying codes. If the REH (A58) module has failed, it will likely throw its own codes (e.g., Id76ACh or Id76ABh regarding position sensor voltage). If the REH module is offline, the EXT module will naturally throw Id788Eh because it is starved of data.

3. 3

   CAN Bus Wiring Test

   Probe the CAN-High and CAN-Low lines between the REH (A58), BDG (A103), and EXT (A62) modules. Verify standard CAN resistance (approx. 60 ohms across the network) and check for continuity.

4. 4

   Test the REH (A58) Output

   Verify that the rear lift position sensor (B139-2) is reading correctly and that the REH module is processing the data. If the rear lift works normally via in-cab controls but the 7-pin connector receives no data, the fault lies in the CAN relay (BDG A103) or the EXT (A62) module.

5. 5

   Module Replacement/Reprogramming

   If wiring is intact and the REH module is transmitting, but the EXT module fails to output the signal to the 7-pin connector, replace the EXT (A62) module. Note that replacing CAN modules usually requires parameter calibration/reinitialization via the CLAAS diagnostic tool.