Conditions for Setting the DTC
WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
C0399 01
The voltage detected by the transfer case control module, on the control circuit and the low reference circuit when both the high side driver and the low side driver are off, is greater than 3.9 V for greater than 5 s.
C0399 02
The voltage detected by the transfer case control module, on the control circuit and the low reference circuit, when both the high side driver and the low side driver are off, is 0.00 V for greater than 5 s.
C0399 04
The voltage detected by the transfer case control module is greater than 0.9 V on the control circuit when the high side driver is off, and 0.0 V on the low reference circuit when the low side driver is off for greater than 5 s.