No, the two wires allow for the motor to turn clockwise or counterclockwise to make the transfer case shift into each gear.
Electronic Shift-On-The-Fly (ESOF) System
The electronic shift 4WD system consists of the following:
- Transfer case
- Transfer Case Control Module (TCCM)
- Vehicle High Speed Controller Area Network (HS-CAN)
- Mode Select Switch (MSS)
- Gearmotor encoder assembly
- 4WD indicators and 4WD system messages in the IPC message center
- Constant Vacuum Hublock (CVH)
- CVH solenoid and vacuum lines
- Vacuum pump (diesel engine only)
Vehicles equipped with an ESOF system allow the operator to choose between 2WD and 2 different 4WD modes. The transfer case is shifted electronically by the TCCM based on the MSS position. Under normal driving conditions, the transfer case is in 2H (4X2), but when desired, the operator can shift into 4H (4X4 HIGH) or 4L (4X4 LOW). The operator can shift between 2H and 4H at any speed. To shift into 4L, the vehicle must be stopped or rolling less than 5 km/h (3 mph) and the transmission in NEUTRAL.
The message center of the IPC displays 4X4 SHIFT IN PROGRESS during a shift, then displays the system mode selected. If shift conditions are not met, the message center displays Information guiding the operator through the correct shifting procedures. If the message center displays SHIFT DELAYED PULL FORWARD, transfer case gear tooth blockage is present. To alleviate the condition move the vehicle forward approximately 1.5 m (5 ft) and if the condition occurs during a 4L shift, place the transmission in neutral to allow the transfer case to complete the shift and fully engage.
The ESOF uses CVHs to engage the front axles. The CVHs are automatically controlled by the TCCM using the hublock vacuum solenoid, which either applies vacuum to the CVHs (4H or 4L) or releases and withholds vacuum to the CVHs (2H). Diesel engine vehicles are equipped with a gear-driven vacuum pump that is mounted to the front of the engine behind the accessory drive cooling fan driver and is serviced as an assembly.
Electronic Locking Differential (ELD) System
The Electronic Locking Differential (ELD) system consists of the following components:
- ELD field coil, located at the rear differential
- Rear differential
- MSS , located on instrument panel
- Vehicles equipped with 4WD electronic shift and ELD share controls in the same MSS ; 4WD mechanical shift and 2WD vehicles use a MSS which controls the ELD only.
The optional ELD system allows the operator to lock the rear differential side gears on slippery and/or off road surfaces. ELD operation is requested by pulling out (4WD electronic shift vehicles) or turning the MSS to the on position (4WD mechanical shift and 2WD vehicles).
Attached is the circuit and the pinpoint test for this concern