Case IH 4057-03 - BCM – BCM: Front wiper low speed motor - short circuit to B+

The control module has detected a short to battery voltage (B+) on the low-speed circuit of the front windshield wiper motor, or that the motor is drawing an excessive electrical load due to an internal short or mechanical binding.

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

1. 1

   Check Fuses and Relays: Verify the cab relay, circuit breaker, and fuses related to the wiper system. A short to B+ can sometimes backfeed or blow related circuit protection.

2. 2

   Test the Switch: Use a voltmeter to check for voltage at the wiper switch terminal. Verify that the switch is correctly outputting 12 volts when moved to the "LO" (low speed) position.

3. 3

   Inspect the Wiring Harness: Trace the wiring harness from the BCM to the front wiper motor. Look for chafed insulation where the low-speed signal wire might be shorting directly to a constant battery power source (B+).

4. 4

   Test the Motor Load: Disconnect the wiper motor. If the fault code changes to an "open circuit" code, the short is likely internal to the wiper motor itself. Also, check the physical wiper linkage for binding, which can cause an excessive load condition.

1. 1

   Disconnect Power

   Turn off the key switch and disconnect the battery to prevent further electrical shorts.

2. 2

   Access the Motor

   Remove the interior cab roof liner or front windshield trim panels to access the front wiper motor assembly.

3. 3

   Disconnect Electricals

   Unplug the multi-pin electrical connector (e.g., Deutsch DT Series connector) from the wiper motor.

4. 4

   Remove Linkage

   Unbolt the wiper arm drive support, remove the special Belleville washer and hex nut, and detach the pivot link/crank assembly from the motor shaft.

5. 5

   Dismount the Motor

   Remove the mounting screws securing the wiper motor bracket to the cab frame.

6. 6

   Install the New Motor

   Mount the replacement wiper motor, reattach the crank assembly and linkage, and secure the mounting hardware.

7. 7

   Reassemble and Test

   Reconnect the electrical connector, restore battery power, and test the wiper motor in all switch positions (Low, High, Park) to ensure the 4057-03 code is cleared.