Case IH 520566-06 - BCM – BCM: Front windshield wiper motor - short circuit to ground

The control module has detected that the voltage on the front wiper motor's power circuit has unexpectedly dropped to zero. This happens when the power supply wire makes direct contact with a ground source (such as the tractor's metal cab frame due to chafed wire insulation) or if the wiper motor itself has suffered an internal short circuit to its casing.

• MAGNUM AFS Connect
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• Magnum Rowtrac

1. 1

   Verify if the front wiper fails to operate entirely or if it immediately blows the wiper circuit fuse when the switch is activated.

2. 2

   Access the wiper motor (usually located under the front headliner above the windshield) and visually inspect the wiring harness routing from the BCM to the motor for pinched wires, chafed insulation, or melted connectors touching the cab frame.

3. 3

   Disconnect the electrical connector at the front wiper motor and use a digital multimeter to check the power supply wire on the harness side for continuity to ground. If there is continuity, the short is in the wiring harness between the BCM and the connector.

4. 4

   If the harness tests clean, test the pins on the wiper motor itself. If the motor's power input pin has continuity to the motor's metal housing, the motor is internally shorted and must be replaced.

1. 1

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical spikes or further shorting during the repair.

2. 2

   Remove Wiper Arm

   From the outside of the cab, lift the cap on the base of the front windshield wiper arm, remove the retaining nut, and pull the wiper arm off the splined motor shaft.

3. 3

   Access the Motor

   Inside the cab, remove the retaining screws and drop the front upper headliner/trim panel to expose the wiper motor assembly.

4. 4

   Remove the Motor

   Disconnect the electrical connector from the motor. Remove the mounting bolts securing the wiper motor bracket to the cab frame and pull the motor assembly out.

5. 5

   Install the New Motor

   Position the new wiper motor assembly into the mounting holes and tighten the retaining bolts.

6. 6

   Reassembly

   Reconnect the electrical connector. Reinstall the exterior wiper arm onto the splined shaft and secure the nut.

7. 7

   Test

   Reconnect the negative battery cable. Turn the key on and test the wiper switch to ensure the short circuit is resolved and the code clears. Reinstall the interior headliner.