Case IH 15997 – MTA CCM & APH (Cab Control Module & Armrest Pod Hub) Stage V MR: Autoguidance Engage/Variable Ratio Activation switch – unexpected value

The control module is receiving a signal from the Autoguidance Engage switch that falls outside of the expected logic states or voltage parameters. This typically points to a switch that is physically stuck, internally degraded (sending erratic resistance values), or sending conflicting simultaneous signals to the module.

• MAXXUM T4E
• VESTRUM CVX
• Puma series
• Puma 165 CVXDrive
• Maxxum series
• Maxxum 135
• Magnum series
• Optum series

1. 1

   Monitor the CAN bus status for the hand controller (diagnostic channel d177 via CAN) in the diagnostic menu to verify if the module registers the switch state changing.

2. 2

   Inspect the Autoguidance Engage button on the Multi-Function Handle (MFH) or armrest for physical damage, sticking, or debris lodged around the rocker.

3. 3

   Inspect the wiring harness and connectors between the switch and the Armrest Pod Hub (APH) for corrosion, moisture ingress, or backed-out pins.

4. 4

   Ensure the PVED-CLS steering valve and autoguidance system are correctly configured as 'present' and detected online in the Pro 1200 or Viper 4+ display.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical shorts while servicing the armrest or Multi-Function Handle.

2. 2

   Access the Switch

   Carefully disassemble the Multi-Function Handle or the specific armrest pod panel housing the Autoguidance Engage switch.

3. 3

   Test the Switch

   Disconnect the switch from the sub-harness. Use a digital multimeter to test the continuity of the switch across its pins while pressing and releasing it. If the resistance is erratic or the switch is stuck closed/open, it must be replaced.

4. 4

   Inspect the Harness

   If the switch tests good, use the multimeter to check the continuity of the wiring harness from the switch connector back to the Armrest Pod Hub (APH). Repair any damaged wires.

5. 5

   Replace and Reassemble

   Install the new Autoguidance Engage switch into the handle/panel and reconnect the harness. Reassemble the armrest components.

6. 6

   Clear and Verify

   Reconnect the battery, turn the key on, and clear the fault codes via the diagnostic menu. Perform a functional test by pressing the Autoguidance Engage button to ensure the system engages properly and code 15997 does not return.