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Dodge Ram Truck 1500-2500-3500. Manual - part 1906

OPERATION

As the position of the selector switch varies, the resistance between the Mode Sensor supply voltage pin and the
Mode Sensor output will vary. Hardware, software, and calibrations within the Transfer Case Control Module
(TCCM) are provided that interpret the selector switch resistance as given in the table below: SELECTOR SWITCH
INTERPRETATION

SELECTOR SWITCH INTERPRETATION

Step

Resistance Range (ohms)

Required Interpretation

<200

Shorted

400-700

NEUTRAL

1050-1450

4LO

1850-2300

4HI

3050-5950

2WD (Default)

9.5-12.5K

In between positions

>15.5K

Open

For resistances between the ranges B-E shown for each valid position (T-Case NEUTRAL, 4LO, 4HI, 2WD), the
TCCM may interpret the resistance as:

•

either of the neighboring valid positions.

•

as an invalid fault position.

For resistances between the ranges E and F shown for 2WD and in-between positions, the TCCM may interpret the
resistance as:

•

the 2WD position.

•

an invalid fault position.

•

a valid in-between position.

For resistances between the ranges F and G shown for in-between positions and fault condition (open), the TCCM
may interpret the resistance as:

•

a valid in-between position.

•

an invalid fault position.

For resistances between the ranges A and B shown for the fault condition (short) and , T-Case NEUTRAL, the
TCCM may interpret the resistance as:

•

the T-Case NEUTRAL position.

•

an invalid fault position.

The LED’s in the selector assembly are illuminated/flashed in the following manner to indicate a particular condition
or state.

•

A solidly illuminated LED indicates a successfully completed shift and the current operating mode of the trans-
fer case. While a shift has been requested but not yet completed, the LED for the desired transfer case posi-
tion is flashed.

•

A flashing operating mode LED for the desired gear indicates that a shift to that position has been requested,
but all of the driver controllable conditions have not been met. This is in an attempt to notify the driver that the
transmission needs to be put into NEUTRAL, the vehicle speed is too great, or some other condition outlined
(other than a diagnostic failure that would prevent this shift) elsewhere (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/TRANSFER CASE CONTROL MODULE - OPERATION) is not met. Note that
this flashing will continue indefinitely until the conditions are eventually met, or the selector switch position is
changed, or if diagnostic routines no longer allow the requested shift.

•

If the driver attempts to make a shift into transfer case NEUTRAL, and any of the driver controllable conditions
are not met, the request will be ignored until all of the conditions are met or until the NEUTRAL select button
is released. Additionally the neutral lamp will flash, or begin to flash while the button is depressed and operator
controllable conditions are not being met. All of the LED’s except the Neutral will flash if any of the operator
controllable conditions for shifting are not met while the Neutral button is depressed. This

toggle

type of fea-

ture is necessary because the TCCM would interpret another request immediately after the shift into transfer
case NEUTRAL has completed.

•

No LED’s illuminated indicate a fault in the transfer case control system.

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TRANSFER CASE - NV273 - SERVICE INFORMATION

DR/DH

MOTOR-SHIFT

DESCRIPTION

The shift motor (1) consists of a permanent magnet
D.C. motor with gear reduction to convert a high
speed-low torque device into a low speed-high torque
device. The output of the device is coupled to a shaft
which internally moves the mode and range forks that
change the transfer case operating ranges. The motor
is rated at 25 amps maximum at 72° F with 10 volts at
the motor leads.

OPERATION

The transfer case shift motor responds to the Transfer Case Control Module (TCCM) commands to move the trans-
fer case shift sector bi-directionally, as required, to obtain the transfer case operating mode indicated by the instru-
ment panel mounted selector switch.

REMOVAL

NOTE: New shift motor assemblies are shipped in the 2WD/AWD position. If a new shift motor assembly will
be installed, it will be necessary to shift the transfer case to the 2WD/AWD position prior to motor removal.

1. Raise the vehicle on a suitable hoist.

2. Disengage the wiring connectors from the shift motor and mode sensor.

3. Remove the bolts holding the shift motor and mode sensor assembly onto the transfer case.

4. Separate the shift motor and mode sensor assembly from the transfer case.

INSTALLATION

1. Verify that the shift sector o-ring is clean and properly positioned over the shift sector and against the transfer case.

NOTE: Verify that the shift motor position and sector shaft orientation are aligned. It may be necessary to
manually shift the transfer case if the shift motor and sector shaft are not aligned.

2. Position the shift motor and mode sensor assembly onto the transfer case.

3. Install the bolts to hold the assembly onto the transfer case. Tighten the bolts to 16-24 N·m (12-18 ft.lbs.).

CAUTION: If the original shift motor and mode sensor assembly bolts are reused, be sure to use Mopar

Lock & Seal or Loctite™ 242 to replenish the lock patch material originally found on the bolts

4. Engage the wiring connectors to the shift motor and mode sensor.

5. Refill the transfer case as necessary.

6. Lower vehicle and verify transfer case operation.

DR/DH

TRANSFER CASE - NV273 - SERVICE INFORMATION

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TIRES/WHEELS

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