Case IH 2642-00 - BCM – Body Control Module (BCM): Left Mirror Heat Circuit Overcurrent / Short to Ground

Indicates an overcurrent, short to ground, or overload condition in the Left Mirror Heat circuit. The system monitors the amperage drawn by the mirror's heating element; when the current exceeds the expected threshold, the controller logs this fault, interpreting it as a faulty load or too many loads on the circuit.

• MAGNUM AFS Connect
• Maxxum series
• Puma series
• Farmall U / Pro Tier 4 series
• Optum series
• Magnum series

1. 1

   Visually inspect the wiring harness leading from the cab door/A-pillar to the left mirror housing for pinched wires, chafing, or exposed copper that could cause a short to ground.

2. 2

   Disconnect the left mirror heater electrical connector and measure the resistance across the mirror glass heating element. A reading of near zero ohms indicates an internal short.

3. 3

   With the mirror disconnected, check the Left_Mirror_Heat_Cmd supply wire from the BCM for continuity to ground. Continuity indicates the wiring harness is shorted.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent any further damage to the BCM during testing and repair.

2. 2

   Access the Harness

   Remove the interior door panel or mirror arm access covers to expose the left mirror wiring harness.

3. 3

   Repair Wiring

   If the diagnostic checks revealed a short to ground in the harness, cut out the damaged section of wire, splice in a new section using weather-resistant heat-shrink butt connectors, and re-loom the harness.

4. 4

   Replace the Mirror Glass

   If the mirror heating element itself is shorted, carefully pry the old mirror glass off its motorized backing plate. Disconnect the two heater spade terminals. Connect the terminals to the new heated mirror glass and snap it firmly into place.

5. 5

   Reassemble and Clear Codes

   Reconnect the battery. Turn the key on, clear the inactive fault codes using the Electronic Service Tool (EST) or via the cab display monitor, and activate the mirror heater to verify the code does not return.