Case IH 4026-05 - BCM – BCM: Right mirror heater open circuit

The fault indicates an open circuit in the right mirror heater. There is a physical break in the electrical path between the control module and the heating element inside the right mirror, preventing the module from detecting any current flowing to the heater when it is commanded on.

• MAGNUM AFS Connect
• Puma series
• Maxxum series

1. 1

   Battery Voltage Check: Ensure the battery's open-circuit voltage is at least 12.6 V, as low voltage can cause auxiliary systems to disable.

2. 2

   Switch Operation Test: Momentarily depress the mirror heater switch to verify if the system attempts to send power during the 5-minute window.

3. 3

   Visual Wiring Inspection: Check the wiring harness routing to the right mirror (often routed through the cab roof/door console) for pinched wires.

4. 4

   Connection Check: Inspect the terminals at the mirror head and the BCM for loose or corroded connections.

1. 1

   Read diagnostic memory

   Read out the diagnostic memory in the instrument panel to confirm the fault is currently active.

2. 2

   Disconnect connector

   Disconnect the electrical connector at the right mirror head.

3. 3

   Check continuity

   Use a multimeter to check for continuity across the mirror's heating element. If the multimeter reads infinite resistance (Ohm), the heating element is burnt out (open circuit).

4. 4

   Replace mirror element

   If the mirror element is faulty, replace the mirror glass/heater assembly.

5. 5

   Trace wiring harness

   If the mirror element has continuity, trace the wiring harness back to the BCM, cleaning and tightening any loose or corroded connections along the path.

6. 6

   Clear fault messages

   Once repaired, use the tractor's multiple display to clear the warning and fault messages from the diagnostic memory.