Case IH 2642-06 - BCM – BCM: Left mirror heater - short circuit to ground

SPN 2642 designates the Left Mirror Heat circuit. FMI 06 indicates a "Short to Ground" or current above normal. This means the electrical current intended to warm the left mirror glass is finding a premature path to the chassis ground, which typically blows the circuit fuse to protect the wiring.

• MAGNUM AFS Connect
• Puma 115
• Puma 125
• Puma 130
• Puma 140
• Puma 145
• Puma 150
• Puma 155
• Puma 160
• Puma 165
• Puma 170
• Puma 175
• Puma 180
• Puma 185
• Puma 195
• Puma 200
• Puma 210
• Puma 215
• Puma 220
• Puma 225
• Puma 230
• Puma 240
• Maxxum 100
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 135
• Maxxum 140
• Maxxum 145
• Maxxum 150
• Optum 270
• Optum 300
• Farmall 95U Pro Tier 4
• Farmall 105U Pro Tier 4
• Farmall 115U Pro Tier 4

1. 1

   Check the Fuses: Locate the cab fuse panel and check the fuse for the heated mirror circuit. A short to ground will almost always blow the fuse.

2. 2

   Inspect the Door Hinge Wiring: The most common failure point for door-mounted mirrors is the wiring harness where it passes through the door hinge. Constant opening and closing of the cab door causes the wires to chafe, break, and short against the metal door frame.

3. 3

   Test the Mirror Element: Carefully remove the mirror mount/glass and disconnect the two wires going to the heating element. Use a multimeter to check for continuity between the power supply wire and a good cab ground. If there is continuity, the wiring harness is shorted.

4. 4

   Isolate the Switch/Relay: Verify that the heated mirror switch and relay are functioning properly and sending power to the circuit when activated.

1. 1

   Disconnect Power

   Disconnect the negative battery terminal before beginning electrical repairs.

2. 2

   Repair the Harness (If Applicable)

   If the diagnostic checks revealed a chafed wire at the door hinge or mirror arm, cut out the damaged section. Splice in a new section of wire using proper crimp connectors and seal it with heat-shrink tubing to prevent moisture ingress.

3. 3

   Replace the Mirror Glass (If the element is internally shorted)

   Carefully pry the old mirror glass out of the mirror head assembly. Disconnect the two electrical spade connectors from the back of the heated glass. Clean the electrical connections to ensure they are free of corrosion. Connect the wiring to the new heated mirror glass. Firmly snap the new mirror glass back into the mirror head housing.

4. 4

   Replace the Blown Fuse

   Install a new fuse of the correct amperage in the cab fuse panel.

5. 5

   Test the System

   Reconnect the battery, turn the ignition on, and activate the heated mirror switch to verify the mirror warms up without blowing the fuse.