Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Location/task/design/function of transfer case control module - GF28.19-P-3100A
MODEL 163
Task:
The transfer case control module (N78) determines the instantaneous operating condition of the transfer case and controls the shift sequences taking into account the driving situation in each case.
Function:
The transfer case control module (N78) receives input signals from the "Low Range" switch (S97/6) and the voltage supply from the battery (terminal 30) and from the ignition lock (terminal 15).
In addition there is a connection to the engine control module (N3/10) via the CAN data bus as well as to the traction system control module (N47), transmission control module (N15/3) and the instrument cluster (A1).
After these input signals are evaluated the electric actuator motor (A55) is actuated which initiates the change of ratio in the transfer case.
Fault memory:
The fault codes of the transfer case are stored in the All-Activity-Module (N10) and can be read out with the HHT via the data link connector (DTC readout) (X11/4).
| Location of transfer case control module | Model 163 | GF28.19-P-3100-01A |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.