Case IH 15995 – PVED-CLS steering controller or MTA CCM: Autoguidance Engage/Variable Ratio Activation switch - short circuit to Vbat

The electrical circuit monitoring the switch used to engage the tractor's autoguidance or variable ratio steering system is detecting unexpected battery voltage (Vbat). This typically points to a wiring harness shorting to a 12V power source or an internal short within the switch itself.

• MAXXUM T4E
• VESTRUM CVX
• Farmall (with CVT)
• Maxxum
• Puma
• Magnum
• Steiger

1. 1

   Check for accompanying fault codes (such as 15996 or 15997) which can help isolate the circuit issue

2. 2

   Visually inspect the Autoguidance Engage / Variable Ratio Activation switch for physical damage, sticking, or liquid intrusion

3. 3

   Inspect the wiring harness between the switch and the PVED-CLS controller for chafing, pinched wires, or melted insulation

4. 4

   Use CAN diagnostics in the AFS Pro 1200 or Viper 4+ display to monitor the live state of the switch and check for a constant 'engaged' signal

1. 1

   Disconnect Power

   Disconnect the machine's battery power to prevent further electrical damage during testing.

2. 2

   Access the Switch

   Remove the trim or panels necessary to access the back of the Autoguidance Engage / Variable Ratio Activation switch on the Multi-Function Handle (MFH) or armrest.

3. 3

   Test the Switch

   Disconnect the switch connector and use a digital multimeter to test for internal continuity/shorts across the switch terminals. If the switch is internally shorted to its power pin, replace the switch.

4. 4

   Trace the Harness

   If the switch tests normal, trace the wiring harness from the switch connector back to the PVED-CLS controller. Look for areas where the wire loom rubs against the cab frame or seat suspension.

5. 5

   Repair Wiring

   Repair any damaged wiring by splicing and sealing the affected wires, ensuring they are routed away from pinch points.

6. 6

   Clear Codes

   Reconnect the battery and cycle the controller power to clear the fault code.

7. 7

   Recalibrate

   If the switch or controller was replaced, perform the steering/autoguidance calibration wizard via the in-cab display to ensure the system recognizes the inputs correctly.