Code I039: Computer Command Ride (CCR) Signal Fault

This code will normally set during CCR diagnostics. If CCR diagnostics were recently performed, clear codes first, test drive vehicle and recheck trouble codes. When this code failure is present, DIC will display SERVICE RIDE CONTROL warning.
CCR controller communicates to IPC through Pink wire. See Fig 1. This code will set if Pink wire circuit voltage is LOW when vehicle speed is less than 5 MPH, or if Pink wire circuit voltage is HIGH when vehicle speed is greater than 15 MPH.
Possible causes of this code are.
- CCR fault detected by CCR control module.
- CCR diagnostic mode entered.
- Loss of IPC vehicle speed information.
- Open or short in Pink, Red/White or Green/White wire circuit. See Fig 1.
- Faulty CCR control module.
  
  Fig 1: Code I039 Wiring Circuit
  Courtesy of GENERAL MOTORS CORP.
Enter diagnostics. See ENTERING SELF-DIAGNOSTICS under SELF-DIAGNOSTICS. If code E024 is also set, a vehicle speed sensor may be at fault. See appropriate BASIC TESTING article in ENGINE PERFORMANCE Section. If code E024 is not set and speedometer does not function, see SPEEDOMETER INOPERATIVE under IPC TESTS .
If code E024 is not set and speedometer functions properly, repair computer command ride control system. Refer to the SUSPENSION - COMPUTER COMMAND RIDE SYSTEM article in the SUSPENSION section. After all repairs are completed, clear all codes and verify correct operation.