Case IH 518504-06 - BCM – BCM: Cab recirculation blower motor control signal - short circuit to ground

The controller has detected that the electrical control signal circuit for the HVAC recirculation blower motor is shorting out against a ground source (such as the machine's chassis or a ground wire).

• MAGNUM AFS Connect
• Case IH AFS Connect series
• Steiger AFS Connect
• Puma AFS Connect

1. 1

   Inspect the wiring harness running from the BCM to the cab roof/HVAC unit for chafing, pinched wires, or melted insulation that could cause the control signal wire to touch bare metal (ground).

2. 2

   Inspect the electrical connector at the recirculation blower motor and the BCM for moisture, corrosion, or bent pins that could bridge the control circuit to ground.

3. 3

   Disconnect the recirculation blower motor and use a multimeter to check for continuity to ground on the control signal wire. If the short remains, the wiring harness is damaged. If the short disappears, the blower motor has an internal short.

1. 1

   Power Down

   Disconnect the machine's battery to prevent electrical spikes or further damage to the BCM.

2. 2

   Access the HVAC Unit

   Remove the cab interior roof panels and the recirculation air filter / charcoal filter to access the blower motor housing.

3. 3

   Disconnect

   Unplug the OE wire connector from the faulty recirculation blower motor.

4. 4

   Remove

   Remove the mounting hardware securing the blower motor assembly to the AC ductwork/evaporator housing and pull the unit out.

5. 5

   Install

   Seat the new blower motor assembly into the housing and secure it with the mounting hardware.

6. 6

   Reconnect

   Plug the electrical connector into the new motor.

7. 7

   Reassemble

   Reinstall the cab air filters and interior roof panels.

8. 8

   Test

   Reconnect the battery, turn the ignition on, and clear the BCM fault codes. Run the HVAC system on all fan speeds to verify the recirculation blower operates correctly without throwing the 518504-06 code.