I'm assuming you have
Transfer Case -Automatic Four Wheel Drive (A4WD) An not Transfer Case -All-Wheel Drive (AWD) Two different system's .
The automatic system is electroniclly controlled . When it has electrical problems it set DTC'S - diagnostic trouble code's in the 4X4 control module . Before replacing part's or trying this an trying that , having the vehicle checked for DTC'S is always the first step in any diagnostic's with these vehicles . Then if not familiar with this system read factroy service repair information . Trying to fix not knowing what your doing never works .
System Function
Hall effect sensor monitors input and output shaft speed.
In the A4WD (C-Trac) system, the GEM varies the torque sent to the front driveline by controlling the transfer case clutch. At rest and under cruising conditions, the GEM activates the transfer case clutch a minimum duty cycle (percentage of time the clutch is turned on), which allows for the slight difference between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. Under any of the following conditions, the GEM will increase the duty cycle in order to prevent or control slip:
- Slip is detected (by using the Hall Effect Sensors)
- Heavy acceleration (throttle position).
Feature inputs:
- Brake ON/OFF switch.
- 4WD mode switch.
- Digital transmission range sensor.
- Clutch switch (manual transmission vehicles only).
- Vehicle speed signal (transmitted from the ABS module).
- Front/rear driveshaft speed sensors.
- Throttle position information from the PCM.
- Contact plate position inputs A, B, C, D.
Feature outputs:
- Solid state clutch relay (pulse width modulated signal: grounded when relay is on, battery potential when relay is off).
- A4WD indicator (ground when activated, open circuit when deactivated).
- 4x4 shift motor relay outputs.
Shifts between A4WD and 4x4 HIGH can be made at any speed. Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.
Feature inputs:
- Front/rear driveshaft speed sensor.
- Vehicle speed signal.
- Throttle position information.
- 4WD mode switch.
Feature outputs:
- Solid state clutch relay (pulse width modulated signal; grounded when relay is on, battery potential when relay is off).
- 4x4 HIGH cluster indicator (ground when activated, open circuit when deactivated).
When shifting into or out of LOW range, the GEM requires that the vehicle speed is less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.
Feature inputs:
- Throttle position information.
- 4WD mode switch.
- Contact plate position inputs A, B, C, D.
- Vehicle speed signal (transmitted from ABS module).
- Brake ON/OFF switch input (battery voltage when brake is depressed, open circuit when not activated).
- Digital transmission range sensor (ground when transmission is in NEUTRAL, open circuit otherwise).
- Start/clutch depressed input (manual transmission only).
Feature outputs:
- 4x4 shift motor relay outputs.
- 4LOW cluster indicators (ground when activated, open circuit when deactivated).
- Solid state clutch relay (pulse width modulated signal; grounded when relay is on, battery potential when relay is off).
- The GEM they talk about is a generic electronic control module .
- Do you know what DTC'S are ?
-
P1763
Transmission Neutral In Tow Indicator Circuit Short to Battery
GEM
REFER to Section 413-09 .
P1764
Transmission Neutral In Tow Indicator Circuit Fault
GEM
REFER to Section 413-09 .
P1804
4WD High Indicator Circuit Failure
GEM
GO to Pinpoint Test C .
P1806
4WD High Indicator Short to Battery
GEM
GO to Pinpoint Test C .
P1808
4WD Low Indicator Circuit Failure
GEM
GO to Pinpoint Test C .
P1810
4WD Low Indicator Short Circuit to Battery
GEM
GO to Pinpoint Test C .
P1812
4WD Mode Select Circuit Failure
GEM
GO to Symptom Chart.
P1815
4WD Mode Select Short Circuit to Ground
GEM
GO to Symptom Chart.
P1820
Transfer Case CW Shift Relay Coil Circuit Open or Short to Ground
GEM
GO to Pinpoint Test B .
P1822
Transfer Case CW Shift Relay Coil Short to Battery
GEM
GO to Pinpoint Test B .
P1824
4WD Electric Clutch Relay Circuit Failure
GEM
GO to Pinpoint Test A .
P1826
4WD Electric Clutch Relay Short to Battery
GEM
GO to Pinpoint Test A .
P1828
Transfer Case CCW Shift Relay Circuit Failure
GEM
GO to Pinpoint Test B .
P1830
Transfer Case CCW Shift Relay Coil Short to Battery
GEM
GO to Pinpoint Test B .
P1836
Transfer Case Front Shaft Speed Sensor Circuit Failure
GEM
GO to Symptom Chart.
P1837
Transfer Case Rear Shaft Speed Sensor Circuit Failure
GEM
GO to Symptom Chart.
P1838
Transfer Case Shift Motor Circuit Failure
GEM
GO to Pinpoint Test B .
P1846
Transfer Case CONTACT PLATE "A" Circuit Failure
GEM
GO to Pinpoint Test B .
P1850
Transfer Case CONTACT PLATE "B" Circuit Failure
GEM
GO to Pinpoint Test B .
P1854
Transfer Case CONTACT PLATE "C" Circuit Failure (GEM Only)
GEM
GO to Pinpoint Test B .
P1858
Transfer Case CONTACT PLATE "D" Circuit Failure (GEM Only)
GEM
GO to Pinpoint Test B .
P1866
Transfer Case Maintenance Required (GEM Only) (4-wheel drive operation can be restored by clearing the DTC and cycling the ignition.)
GEM
GO to Pinpoint Test B .
P1867
Transfer Case Contact Plate General Circuit Failure (GEM Only)
GEM
GO to Pinpoint Test B .
P1874
Automatic Hall Effect Sensor Power Circuit Failure
GEM
GO to Symptom Chart.
P1875
Automatic Hall Effect Sensor Power Circuit Short to Battery (GEM Only)
GEM
GO to Symptom Chart.
P1891
Transfer Case Contact Plate Ground Return Open Circuit
GEM
GO to Pinpoint Test B .
- Your best bet , have it towed to a qualified repair shop . You have not the knoweldge or diagnostic equipment to fix it.