Case IH 12550: Trailer brake test switch open circuit or short to ground

The wiring circuit for the trailer brake test switch is either broken/disconnected (open circuit) or has an unintended connection to a ground source (short to ground), preventing the switch from sending the correct signal to the control module.

• MAXXUM T4E
• VESTRUM CVX
• Case IH tractors with ActiveDrive 8 transmission

1. 1

   Access the C-pillar control panel to locate the trailer brake test switch

2. 2

   Inspect the wiring harness connected to the switch for breaks, chafing, or unintended ground connections

3. 3

   Test the trailer brake test switch for electrical continuity

1. 1

   Replace

   Replace the faulty rocker switch on the C-pillar.

2. 2

   Repair

   Repair the damaged section of the wiring harness.