Case IH 520566-03 - BCM – BCM: Front windshield wiper motor - short circuit to B+

The control circuit for the front windshield wiper motor is experiencing a Short circuit to B+ (Battery Positive). This means the control module is detecting unexpected 12-volt power on the wiper motor's circuit, which usually happens when a wire chafes and touches a live power wire, or when there is an internal short within the motor or the module itself.

• MAGNUM AFS Connect
• Magnum 340
• Magnum 400 AFS Connect

1. 1

   Inspect the wiring harness running from the cab roof/cowl area down to the BCM for pinched wires, melted insulation, or chafing that could expose the wiper control wire to a constant 12V source.

2. 2

   Perform a disconnect test: Turn the key ON (engine OFF) and disconnect the electrical connector at the front windshield wiper motor. If the code changes to Open Circuit (05), the short is internal to the wiper motor. If the code remains Short to B+ (03), the short is in the wiring harness or BCM.

3. 3

   With the battery disconnected and the BCM and wiper motor unplugged, use a multimeter to check for continuity between the wiper motor signal wire and any 12V power supply wires in the harness.

4. 4

   Inspect the BCM pins for water ingress, corrosion, or bent pins that could be bridging a live power pin to the wiper circuit.

1. 1

   Power Down

   Turn off the tractor ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Remove the Wiper Arm

   Lift the plastic cap at the base of the front windshield wiper arm, remove the retaining nut, and carefully pull the wiper arm off the splined motor shaft.

3. 3

   Access the Motor

   Remove the interior cab trim panels or exterior cowl cover (depending on exact cab configuration) to access the wiper motor assembly.

4. 4

   Disconnect and Remove

   Unplug the electrical harness connector from the motor. Remove the mounting bolts securing the wiper motor bracket to the cab frame.

5. 5

   Install the New Motor

   Position the new wiper motor assembly, secure the mounting bolts, and plug in the electrical connector.

6. 6

   Reassemble

   Reinstall the cab trim/cowl panels. Reattach the wiper arm to the splined shaft in the correct "parked" position and tighten the retaining nut.

7. 7

   Test

   Reconnect the battery, turn the key ON, clear the inactive fault codes from the BCM using the AFS display, and test the wiper function across all speeds.