Case IH 520587-05 - BCM – BCM: Trailer right turn indicator - Current Below Normal or Open Circuit

The control module is sending a voltage signal to the trailer's right turn indicator but is detecting infinite resistance (no current draw). This means the electrical circuit is broken.

• MAGNUM AFS Connect
• Magnum Series (e.g., AFS Connect Magnum 180-380)
• Maxxum Series (e.g., Maxxum 100, 110, 115, 135)
• Farmall Series (e.g., Farmall 85N, 95C, 115U)
• Puma Series
• Steiger Series

1. 1

   Verify the trailer's 7-pin connector is fully seated into the tractor's receptacle

2. 2

   Inspect the trailer's right turn signal bulb for a blown filament (test the trailer on another vehicle or check the bulb directly)

3. 3

   Inspect the tractor's 7-pin socket for bent, spread, loose, or heavily corroded terminals

4. 4

   Disconnect the negative battery cable and perform a multimeter continuity test from the right turn signal pin on the tractor's socket back to the BCM harness (an 'OL' reading indicates a physical break in the wiring)

5. 5

   Check the rubber boot behind the 7-pin socket for tears or missing pieces that could allow water and dirt to enter and corrode terminals

1. 1

   Address the Trailer (If Applicable)

   If the fault is isolated to the trailer, replace the burnt-out right turn signal bulb or repair the trailer's internal wiring.

2. 2

   Clean the Socket

   If the tractor's 7-pin socket shows minor corrosion, spray it with a high-quality electrical contact cleaner and use a terminal brush to clean the pins.

3. 3

   Replace the 7-Pin Socket (If Damaged)

   Disconnect the tractor's battery. Remove the mounting bolts securing the 7-pin socket to the rear bracket. Pull back the rubber protective boot and disconnect the wiring harness from the rear of the socket. Cut away any heavily corroded wire ends and crimp/solder on new repair terminals if necessary. Wire the new 7-pin socket according to the standard agricultural pinout, ensuring the right turn signal wire is securely fastened. Slide a new rubber boot over the rear of the socket to ensure a watertight seal. Bolt the new socket back onto the bracket.

4. 4

   Clear the Code

   Reconnect the battery, plug in a known-good trailer (or a trailer light tester), and activate the right turn signal. The BCM should detect the proper current draw, and the fault code will either move to an inactive state or can be cleared via the diagnostic menu.