Dodge dakota 2002 Service Manual page 397

8E - 16 ELECTRONIC CONTROL MODULES
TRANSFER CASE CONTROL MODULE (Continued)
Fig. 9 Transfer Case Control Module (TCCM)
1 - INSTRUMENT PANEL
2 - TRANSFER CASE CONTROL MODULE (TCCM)
3 - TRANSFER CASE SELECTOR SWITCH
• Diagnostic Requests
• Manual Transmission and Brake Applied
• PRNDL
• Ignition Status
• ABS Messages
Once the TCCM determines that a requested shift
is allowed, it actuates the bi-directional shift motor
as necessary to achieve the desired transfer case
operating mode. The TCCM also monitors the mode
sensor while controlling the shift motor to determine
the status of the shift attempt.
Several items can cause the requested shift not to
be completed. If the TCCM has recognized a fault
(DTC) of some variety, it will begin operation in one
of four Functionality Levels. These levels are:
• Level Zero - Normal Operation.
• Level One - Only Mode Shifts Are Allowed.
• Level Two - Only Mode Shifts and Shifts Into
LOW Are Allowed (No Neutral Shifts Are Allowed).
• Level Three - No Shifts Are Allowed
The TCCM can also be operating in one of three
possible power modes. These power modes are:
• Full Power Mode is the normal operational
mode of the module. This mode is achieved by normal
PCI bus traffic being present and the ignition being
in the RUN position.
• Reduced Power Mode will be entered when
the ignition has been powered off. In this state, the
module will shut down power supplied to external
devices, and to electronic interface inputs and out-
puts. From this state the module can enter either
Sleep Mode or Full Power Mode. To enter this mode,
the module must receive an ignition message denot-
ing that the ignition is off, or not receive any mes-
sages for 5 ±0.5 seconds. To exit this mode, the
Location
module must receive one ignition message that
denotes that the ignition is in the RUN position.
• Sleep Mode will be entered, from the Reduced
Power Mode, when no PCI traffic has been sensed for
20 ±1 seconds. If during Sleep Mode the module
detects PCI bus traffic, it will revert to the Reduced
Power mode while monitoring for ignition messages.
It will remain in this state as long as there is traffic
other than run or start messages, and will return to
Sleep mode if the bus goes without traffic for 20 ±1
seconds.
SHIFT REQUIREMENTS
If the TCCM is in full power mode and at function-
ality level zero, it uses the following criteria to deter-
mine if a shift is allowed.
If any of the driver controllable conditions are not
met once the shift request is recognized, the TCCM
will solidly illuminate the source position's LED and
flash the desired position's LED for all shifts except
NEUTRAL. The NEUTRAL shift LED strategy will
be discussed later.
Mode shifts will be allowed regardless of trans-
mission gear or vehicle speed, whenever the following
conditions are met:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
• A change in the Selector switch state indicates
that a mode shift has been requested.
• A valid mode sensor signal is being sensed by
the TCCM.
• Proper transmit/receive messages are occurring
on the PCI bus.
• Ignition key switch is in the RUN position.
Range shifts will be allowed only if all of the fol-
lowing conditions are met:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
• A change in the Selector Switch state indicating
a range shift has been requested.
• Transmission in NEUTRAL signal must be rec-
ognized for at least 1.5 seconds ±100 msec. (Automat-
ic transmissions only)
• Proper transmit/receive messages are occurring
on the PCI bus.
• Clutch signal is recognized for 500 msec ± 50
msec (Manual transmissions only).
• Vehicle speed is less than or equal to 4.8 km/hr
(3 miles per hour).
• Ignition key switch is in the RUN position.
• 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:
• Front and rear wheel speed are within 21 km/hr
(13 mph).
DR