Case IH 520587-03 - BCM – BCM: Trailer right turn indicator - short circuit to B+

The circuit responsible for sending the right turn signal to the trailer is receiving unintended battery voltage (12V+), indicating a short circuit to a power source.

• MAGNUM AFS Connect
• Steiger AFS Connect
• Optum
• Puma

1. 1

   Disconnect the trailer from the tractor's rear 7-pin implement socket and clear the fault code to isolate if the short is in the trailer or tractor.

2. 2

   Inspect the tractor's 7-pin implement socket for heavy corrosion, water intrusion, or bent pins bridging the right turn pin (Pin 5) to a constant 12V+ source.

3. 3

   Trace the wiring harness from the rear 7-pin socket back to the BCM, looking for pinched wires, chafing, or melted insulation.

4. 4

   Probe the BCM output pin for the trailer right turn signal to see if it outputs a constant 12V when the switch is off and harness unplugged, indicating an internal BCM failure.

1. 1

   Resolve Harness/Socket Shorts

   If the diagnostic checks reveal a short in the wiring harness, repair the damaged section of the wire and apply heat-shrink tubing.

2. 2

   Replace the Implement Socket

   If the 7-pin socket is internally shorted due to corrosion or physical damage, unbolt the socket from the rear bracket, disconnect the pigtail, and install a new OEM 7-pin socket.

3. 3

   BCM Replacement/Update

   If the BCM is internally shorted, the module must be replaced. Note that BCM replacements require programming/flashing with the latest software (e.g., software version 91770803 for 12V BCMs) using the Case IH Electronic Service Tool (EST).

4. 4

   Verification

   Reconnect the trailer (or a test light board), turn on the tractor, and activate the right turn signal to verify the code is cleared and the light flashes correctly.