Case IH 518889-06 - BCM – BCM: Ambient white illumination driver - short circuit to ground

The control module has detected a short to ground on the circuit responsible for powering the ambient white cab lighting. This usually means the power wire is chafed and touching the chassis, or there is an internal short within the light fixture itself.

• MAGNUM AFS Connect
• Steiger / Quadtrac AFS Connect

1. 1

   Visually inspect the wiring harness leading from the BCM to the ambient white cab light fixtures. Look for pinched wires, chafing against the cab frame, or melted insulation.

2. 2

   Disconnect the ambient white illumination light fixtures. If the fault changes from 'short circuit to ground' (06) to 'open circuit' (05), the short is internal to the light fixture.

3. 3

   With the lights and the BCM disconnected, use a multimeter to check for continuity between the ambient light power supply wire and a known good chassis ground. If there is continuity, the wiring harness is shorted.

1. 1

   Disconnect battery

   Disconnect the tractor's battery power to prevent damage to the BCM.

2. 2

   Locate short

   Locate the shorted section of the wiring harness or the faulty ambient light fixture identified during diagnostics.

3. 3

   Repair wiring

   If the wiring is chafed, repair the wire using OEM-approved heat-shrink connectors and re-loom the harness to prevent future rubbing.

4. 4

   Replace light fixture

   If the light fixture is internally shorted, replace the ambient light assembly.

5. 5

   Reconnect and test

   Reconnect the battery, clear the inactive fault codes via the AFS Pro 1200 display, and test the ambient cab lighting to verify the repair. (Note: A software update for the BCM, referenced as '91770803 SOFTWARE, BCM 12V', may be required if the BCM is acting erratically).