Case IH 520592-00 - BCM – BCM: Mirror heater indicator - too many loads or faulty load

The control module has detected that the current draw on the mirror heater circuit exceeds the expected operational range, which is typically caused by a short circuit to ground, a failed heating element, or damaged wiring creating a parasitic load.

• MAGNUM AFS Connect
• Puma 210
• Magnum 380
• Maxxum 5120
• 9240
• 6150 (Tier 4B)

1. 1

   Check the mirror heater circuit protection (10A Mini Red fuse F-012) for a blown fuse, which confirms a hard short

2. 2

   Test the timer function to verify if the BCM is failing to time out the circuit after 5 minutes, leading to an overload

3. 3

   Inspect the 2-pin connection cable wiring harness where it pivots at the mirror arm or cab door for chafing, a common cause of short circuits

4. 4

   Inspect the mirror heater switch (X-805) and its 0.5 - 1.0mm female terminal connectors for melting or internal shorts

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the battery to prevent further damage to the BCM.

2. 2

   Isolate the Fault

   Disconnect the 2-pin connection cable at the mirror head.

3. 3

   Check for Shorts

   Use a multimeter to check for continuity to ground on the power supply wire coming from the BCM. If continuity exists, trace the harness back to the cab and repair the chafed wire.

4. 4

   Test the Heating Element

   Measure the resistance of the mirror glass heating element. If it reads out of specification (nearly zero ohms), the heating element is shorted and the mirror glass/head must be replaced.

5. 5

   Replace the Fuse

   If the 10A F-012 fuse was blown, replace it with a new 10A Mini Red fuse.

6. 6

   Reassemble and Test

   Reconnect the mirror, restore battery power, and momentarily depress the mirror heater switch. Verify that the indicator illuminates without logging the 'faulty load' code.