LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 958 (Trailer Brake Control System) >> Diagnostic Information and Procedures >> DTC C1112 >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: All electrical components and accessories must be turned OFF and allowed to power down.
  1. Ignition OFF, disconnect the harness connector at the solid state relay.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal F and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test or replace the trailer brake controller solid state relay.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal E and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TBCM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the TBCM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the TBCM.
  5. If all circuits test normal, replace the trailer brake solid state relay.
scientia non olet · About LEMON Manuals