RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Mode shifts will be allowed regardless of transmission gear or vehicle speed, whenever the following conditions are met:
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Front and rear wheel speed are within 21 km/hr (13 mph).
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A change in the Selector switch state indicates that a mode shift has been requested.
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A valid mode sensor signal is being sensed by the TCCM.
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Proper transmit/receive messages are occurring on the PCI bus.
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Ignition key switch is in the RUN position.
Range shifts will be allowed only if all of the following conditions are met:
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Front and rear wheel speed are within 21 km/hr (13 mph).
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A change in the Selector Switch state indicating a range shift has been requested.
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Transmission in NEUTRAL signal must be recognized for at least 1.5 seconds +/- 100 msec. (Automatic transmissions only)
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Proper transmit/receive messages are occurring on the PCI bus.
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Clutch signal is recognized for 500 msec +/- 50 msec (Manual transmissions only).
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Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour).
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Ignition key switch is in the RUN position.
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A valid mode sensor signal is being sensed by the TCCM.
A shift into transfer case Neutral will be allowed only if all of the following conditions are met:
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Front and rear wheel speed are within 21 km/hr (13 mph).
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The recessed Neutral Selection switch has been depressed continuously for 4.0 seconds +/- 100 msec while all shift conditions have been
continuously met.
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Transmission in NEUTRAL signal recognized from the bus. (Automatic transmissions only)
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Clutch signal is recognized from the bus (Manual transmissions only).
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Proper message transmissions/receptions are occurring on the PCI bus.
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Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour).
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Ignition key switch is in the RUN position, engine OFF.
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Foot Brake is applied.
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A valid mode sensor signal is being sensed by the TCCM.
A shift out of transfer case Neutral will be allowed only if all of the following conditions are met:
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Front and rear wheel speed are within 21 km/hr (13 mph).
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The recessed Neutral Selection switch has been depressed continuously for 1.0 seconds +/- 100 msec while all shift conditions have been
continuously met.
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Transmission in NEUTRAL signal recognized from the bus.(Automatic transmissions only)
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Clutch signal is recognized from the bus (Manual transmissions only).
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Proper message transmissions/receptions are occurring on the PCI bus.
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Vehicle speed is less than or equal to 4.8 km/hr (3 miles per hour).
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Ignition key switch is in the RUN position.
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Foot Brake is applied.
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A valid mode sensor signal is being sensed by the TCCM.
SHIFT SEQUENCES
Once all the driver controllable conditions for the requested shift have been met, the TCCM begins a shift timer with a maximum duration of 1
second per 'D' channel transition. If the shift timer expires before the TCCM recognizes to correct mode sensor code, the shift is considered to
have been blocked. The blocked shift will increment the blocked shift counter by one. The TCCM strategy for handling blocked shifts will be
described later. The process the TCCM performs for the various shifts will be described first.
Range And Mode Shifts
The process for performing all the range and mode shifts are the same. The following steps describe the process.
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Allow time for Selector Switch debounce; 250 msec +/- 50 msec.
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Extinguish the source gear's LED while flashing desired transfer case position's LED.
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Engage the shift motor for a maximum of 1 second +/- 100 msec per 'D' channel transition in the destination gear's direction while monitoring
the mode sensor channel transitions.
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Disengage the shift motor when the correct mode sensor code is recognized.
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Solidly illuminate the selected gear's LED.
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Transmit a bus message that the transfer case shift is complete.
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If the desired mode sensor code is not received after the shift timer expires (ie. a blocked or other condition exists), stop driving the motor and
wait for 200 msec +/- 50 msec. The shift motor is then reversed in the direction back toward the source gear for up to 1.0 seconds +/- 100
msec. per 'D' channel. The TCCM waits for 2.0 seconds +/- 50 msec. and repeats the attempt to shift to the desired position.
The exception to the preceding sequence is when a shift from 4L to 2WD/AWD is requested. If 2WD/ AWD is requested from the 4L position, the
transfer case is first driven to the 4H position. If the 4H position is reached, the transfer case is then driven back to the 2WD/AWD position and
the shift is considered complete. If the transfer case does not reach any the 4H position, but is in the 2WD/AWD 'D' channel, or the 2WD/AWD
between gear position on the 4H side of 2WD/AWD, the shift is also considered complete.
