2-Speed Torque-On-Demand (TOD) Operation
The automatic 4-wheel drive (A4WD) system is a 2-speed torque-on-demand (TOD) operation that utilizes the following components:
- Transfer case
- 4-wheel drive (4WD) control module (integral to the powertrain control module [PCM])
- Mode select switch (MSS)
- Gearmotor encoder assembly (part of the transfer case shift motor)
- Transfer case shift motor
- Shift motor sense plate (part of the gearmotor encoder assembly)
Principles of Operation
Transfer Case Shift Motor
The externally mounted transfer case shift motor, located at the rear of the transfer case, turns the shift cam assembly. As the shift cam assembly turns, it positions the reduction shift fork for desired transfer case operation. An integral position sensor in the shift motor provides shift motor position information to the 4WD control module.
Mode Select Switch (MSS)
The push button MSS, mounted on the instrument panel, allows the operator to select the 4x4 Auto, 4x4 High, and 4x4 Low transfer case operating modes. The indicator light, on the instrument cluster push button, will illuminate only when the 4x4 Low position is engaged.
Visual Inspection Chart
Mechanical
Electrical
- Axle shafts and CV joints
- Driveshaft and universal joints
- Fluid leaks
- Matching tire sizes
- Transfer case shift motor
- Battery junction box (BJB) fuses:
- Central junction box (CJB) fuses:
- 4x4 module (PCM)
- Wiring harness
- Gearmotor encoder contact plate
- Connector(s)
- Circuitry
- Mode indication switch (MSS)
- If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the concern is not visually evident, connect the diagnostic tool to the data link connector and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
- check that the program card is correctly installed.
- check the connections to the vehicle.
- check the ignition switch position.
- If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.
- Carry out the diagnostic tool data link test. If the diagnostic tool responds with:
- CAN circuit fault; all electronic control units no response/not equipped, refer to Section 418-00 .
- No response/not equipped for 4WD module (PCM), Go To Pinpoint Test G .
- System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out the 4WD module (PCM) self test.
- If the DTCs retrieved are related to the concern, go to the 4WD Control Module (PCM) Diagnostic Trouble Code (DTC) Index to continue diagnostics. 4WD Control Module (PCM) Diagnostic Trouble Code (DTC) Index
DTC
Description
Source
Action
B1317
Battery Voltage HIGH
4WD Module (PCM)
REFER to Section 414-00 .
B1318
Battery Voltage LOW
4WD Module (PCM)
REFER to Section 414-00 .
B1319
Driver Door Ajar Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test M .
B1322
Driver Door Ajar Circuit Short To Ground
4WD Module (PCM)
Go To Pinpoint Test M .
B1342
ECU is Defective
4WD Module (PCM)
CLEAR the DTCs. REPEAT the 4x4 module (PCM) self test. If DTC B1342 is retrieved, INSTALL a new 4x4 module (PCM). REFER to Section 303-14 . CLEAR the DTCs. REPEAT the self test.
B1483
Brake Pedal Input Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test M .
B1485
Brake Pedal Input Short to Battery
4WD Module (PCM)
Go To Pinpoint Test M .
C1729
Transfer Case Unable to Transition Between 4H and 4L
4WD Module (PCM)
Go To Pinpoint Test K .
C1970
4WD Low Mode Switch LED Short to Battery
4WD Module (PCM)
Go To Pinpoint Test K .
C1971
4WD Low Mode Switch LED Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test K .
P1707
Transfer Case NEUTRAL or PARK/NEUTRAL Indication Circuit
4WD Module (PCM)
Go To Pinpoint Test M .
P1812
Transmission 4-Wheel Drive Mode Select Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test K .
P1815
Transmission 4-Wheel Drive Mode Select Short Circuit to Ground
4WD Module (PCM)
Go To Pinpoint Test K .
P1816
Transmission NEUTRAL Safety Switch Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test M .
P1819
Transmission NEUTRAL Safety Switch Circuit Short to Ground
4WD Module (PCM)
Go To Pinpoint Test M .
P1820
Transfer Case Clockwise Shift Relay Coil Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test K .
P1822
Transfer Case Clockwise Shift Relay Coil Circuit Short To Battery
4WD Module (PCM)
Go To Pinpoint Test K .
P1824
4-Wheel Drive Clutch Relay Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test H .
P1826
4-Wheel Drive Low Clutch Relay Short Circuit to Battery
4WD Module (PCM)
Go To Pinpoint Test H .
P1827
4-Wheel Drive Low Clutch Relay Short Circuit to Ground
4WD Module (PCM)
Go To Pinpoint Test H .
P1828
Transfer Case Counterclockwise Shift Relay Coil Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test K .
P1830
Transfer Case Counterclockwise Shift Relay Coil Circuit Short To Battery
4WD Module (PCM)
Go To Pinpoint Test K .
P1849
Transfer Case Contact Plate A Short Circuit to Ground
4WD Module (PCM)
Go To Pinpoint Test K .
P1853
Transfer Case Contact Plate B Short Circuit to Ground
4WD Module (PCM)
Go To Pinpoint Test K .
P1857
Transfer Case Contact Plate C Short Circuit to Ground
4WD Module (PCM)
Go To Pinpoint Test K .
P1861
Transfer Case Contact Plate D Short Circuit to Ground
4WD Module (PCM)
Go To Pinpoint Test K .
P1867
Transfer Case Contact Plate General Circuit Failure
4WD Module (PCM)
Go To Pinpoint Test K .
P1891
Transfer Case Contact Plate Ground Return Open Circuit
4WD Module (PCM)
Go To Pinpoint Test K .
U1900
CAN Communication BUS Fault
4WD Module (PCM)
REFER to Section 418-00 .
U2023
External Node Fault
4WD Module (PCM)
REFER to Section 418-00 .
U2051
One Or More Calibration Files Missing/Corrupt
4WD Module (PCM)
Reprogram/Reflash the 4x4 module. REFER to Section 418-00 .
-
For All Other DTCs
4WD Module (PCM)
REFER to Section 418-00 .
- Your best bet mite be to take it to a qualified repair shop !
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