Case IH 518932-14 - BCM – BCM: Air/vent distribution mode switch - invalid input voltage

The fault code indicates an issue with the Air/vent distribution mode switch where the control module is receiving an "invalid input voltage".

• MAGNUM AFS Connect
• Magnum series tractors
• Steiger series tractors
• Puma series tractors
• Axial-Flow combines

1. 1

   Verify the Fault: Clear the code using an EASy diagnostic tool or equivalent scanner to see if the code is active or stored.

2. 2

   Check the Switch: Inspect the physical air/vent distribution mode switch on the cab climate control panel for physical damage or sticking buttons.

3. 3

   Wiring and Harness Inspection: Check the wiring harness between the HVAC control panel/switch and the BCM for chafing, pinched wires, or loose connections.

4. 4

   Voltage Testing: Back-probe the switch connector to verify if the reference voltage and ground supplied by the BCM are within specification, and check if the signal voltage changes smoothly when the switch is operated.

1. 1

   Disconnect battery

   Disconnect battery power before servicing cab electrical components.

2. 2

   Access HVAC control unit

   Remove the interior trim panels to access the rear of the HVAC control unit.

3. 3

   Repair wiring

   Repair any damaged wiring in the harness between the switch and the BCM.

4. 4

   Replace switch or module

   Replace the air/vent distribution mode switch (or the entire climate control module, if the switch is integrated and cannot be serviced separately) if the wiring tests good but the switch output voltage remains invalid.

5. 5

   Clear fault codes

   Reconnect power and clear the BCM fault codes.