Upon power-up of the ITCM ABS System (Permanent or Stoplight Power), the ABS warning lights should come “ON” for 3 seconds and then go “OFF.” If the ABS warning light stays “ON,” it may be caused by improper light wiring, or by a fault in the ITCM ABS System.

Check for diagnostic fault codes. If anything other than a "07" or "No Active DTCs" is displayed, review the ITCM Diagnostic Codes Troubleshooting section on pages 29-33 of the ITCM Installation & Service Guide (L31286) for possible solutions. After repairing the problem, clear all stored faults and test again.
If a "07" is displayed, but there was an 11 - 14 (Sensor Low), or 21 - 24 (Sensor Signal) fault stored in memory, correct the problem and drive the trailer or rotate the wheel affected >1 mph using permanent power to get the ABS light to turn "OFF".+
If a "07" is displayed, there are no faults stored in memory, and the ABS light is still "ON", the ABS light is wired incorrectly. Remove the main wire harness 5 pin connector at the ECU (Electronic Control Unit) and verify continuity between pin "D". Refer to ABS power drop pin out on page 16. The remaining light wire must be grounded to the trailer chassis or connected to the SAE J560 7-way connector ground wire. Check for continuity between the ABS light wire and ground. Repair as necessary and retest.
If the solenoid does not energize with a "CLICK CLICK" when power is applied, or the diagnostic tool has nothing on the display, check power on the blue or red wire of the 7-way connector, as well as, the ABS power cord. Refer to ABS power drop pin out on page 16 of the Installation/Service Guide (L31286). Verify power source is >10 volts when connected to ABS.