Case IH 2642-05 - BCM – Body Control Module (BCM): Mirror 1 Heater / Left Mirror Heater - Current Below Normal or Open Circuit

The control module is commanding the left mirror heater to turn on, but it is not detecting the expected electrical current flow. The system has detected a break in the circuit (an open circuit), which is typically caused by a burnt-out heating element inside the mirror glass, a broken wire, a disconnected plug, or a blown fuse/relay.

• MAGNUM AFS Connect
• Puma
• Magnum
• Steiger
• Optum
• Maxxum

1. 1

   Check Fuses and Relays: Locate the cab power distribution center and check the specific fuse and relay for the left mirror heater.

2. 2

   Inspect Connectors: Disconnect the left mirror wiring harness connector. Inspect the plug for corroded, damaged, or pushed-out pins.

3. 3

   Test the Heater Element: Using a multimeter, measure the resistance (Ohms) of the heater element directly at the mirror glass connector. If the reading is very high or 'OL' (Open Loop), the heating grid inside the glass has failed.

4. 4

   Check Wiring Continuity: If the mirror glass tests good, check the wiring harness between the BCM and the left mirror connector for continuity to ensure there are no broken wires.

5. 5

   Verify Ground: Check the ground circuit from the mirror connector to the chassis ground point to ensure there is no high resistance.

1. 1

   Disconnect Power

   Always disconnect the battery negative cable before performing electrical repairs.

2. 2

   Replace the Failed Component

   If the mirror element is open: Carefully pry the old mirror glass out of the housing (it usually snaps into the motor actuator). Disconnect the two small heater wires from the back of the glass. Connect the wires to the new heated mirror glass and snap it firmly back into the housing. If the wiring is broken: Repair the broken wire using weather-sealed butt connectors or replace the damaged connector pin. If the relay/fuse is blown: Replace the blown component and retest the circuit for shorts before powering it up.

3. 3

   Reassemble and Test

   Reconnect the battery negative cable. Use a diagnostic scan tool to clear the inactive 2642-05 fault code from the BCM. Turn on the mirror heater switch and verify that the left mirror glass warms up.