Dodge 2000 DURANGO Service Manual page 379

DN
DESCRIPTION AND OPERATION (Continued)
rotor. The clockspring mechanism provides turn sig-
nal cancellation as well as a constant electrical con-
nection between the horn switch, driver side airbag
module, speed control switches and remote radio
switches on the steering wheel and the instrument
panel wire harness on the steering column. The
housing of the clockspring is secured to the steering
column and remains stationary. The rotor of the
clockspring, including the turn signal cancelling cam
lobes rotate with the steering wheel.
The turn signal cancelling cam is integral to the
clockspring and cannot be repaired. If faulty or dam-
aged, the entire clockspring assembly must be
replaced. Refer to Clockspring in the Removal and
Installation section of Group 8M - Passive Restraint
Systems for the clockspring service procedures.
OPERATION
The turn signal cancelling cam has two lobes
molded into the lower surface of the clockspring
rotor. When the turn signals are activated by moving
the multi-function switch control stalk to a detent
position, a turn signal cancel actuator is extended
from the inside surface of the multi-function switch
housing toward the clockspring rotor. When the
steering wheel is rotated during the turn, one of the
two turn signal cancelling cam lobes will contact the
turn signal cancel actuator, releasing the multi-func-
tion switch control stalk from its detent and cancel-
ling the turn signal event.
COMBINATION FLASHER
DESCRIPTION
The combination flasher is a smart relay that func-
tions as both the turn signal system and the hazard
warning system flasher. The combination flasher con-
tains active electronic Integrated Circuitry (IC) ele-
ments. This flasher is designed to handle the current
flow requirements of the factory-installed lighting. If
supplemental lighting is added to the turn signal
lamp circuits, such as when towing a trailer with
lights, the combination flasher will automatically try
to compensate to keep the flash rate the same.
While the combination flasher has a International
Standards Organization (ISO)-type relay terminal
configuration or footprint, the internal circuitry is
much different. The combination flasher does not use
standard ISO-relay inputs or provide ISO-relay type
outputs or functions. The combination flasher should
never be substituted for an ISO-relay or replaced
with an ISO-relay, or else component and vehicle
damage may occur.
Because of the active electronic elements within
the combination flasher, it cannot be tested with con-
ventional automotive electrical test equipment. If the
TURN SIGNAL AND HAZARD WARNING SYSTEMS
combination flasher is believed to be faulty, test the
turn signal system and hazard warning system cir-
cuits as described in this group. Then replace the
combination flasher with a known good unit to con-
firm system operation.
The combination flasher has five blade-type termi-
nals intended for the following inputs and outputs:
fused B(+), fused ignition switch output, ground, turn
signal circuit, and hazard warning circuit. Constant
battery voltage and ground are supplied to the
flasher so that it can perform the hazard warning
function, and ignition switched battery voltage is
supplied for the turn signal function. Refer to Turn
Signals in the Contents of Group 8W - Wiring Dia-
grams for complete circuit diagrams.
The combination flasher is located in the relay and
fuse block which is located on the back of the junc-
tion block near the dash panel under the left end of
the instrument panel. The combination flasher can-
not be repaired or adjusted and, if faulty or damaged,
it must be replaced.
OPERATION
The IC within the combination flasher (Fig. 2) con-
tains the logic that controls the flasher operation and
the flash rate. Pin 6 of the IC receives a sense volt-
age from the hazard warning circuit of the multi-
function switch. When the hazard warning switch is
turned on, the hazard on sense" voltage will become
low due to the circuit being grounded through the
turn signal bulbs. This low voltage sense signals the
IC to energize the flash control Positive-Negative-
Positive (PNP) transistor at a pre-calibrated flash
rate or frequency. Each time the PNP transistor ener-
gizes the hazard warning circuit, the pin 6 "hazard
on sense" voltage will become high and the IC signals
the PNP transistor to de-energize the circuit. This
cycling will continue until the hazard warning switch
is turned off.
Likewise, pin 8 of the IC receives a sense voltage
from the turn signal circuits of the multi-function
switch. When the left or right turn signal switch is
turned on, the "turn signal on sense" voltage will
become low due to the circuit being grounded
through the turn signal bulbs. This low voltage sense
signals the IC to energize the flash control PNP tran-
sistor at a pre-calibrated flash rate or frequency.
Each time the PNP transistor energizes the turn sig-
nal circuit, the pin 8 "turn signal on sense" voltage
will become high and the IC signals the PNP transis-
tor to de-energize the circuit. This cycling will con-
tinue until the right or left turn signal switch is
turned off.
A special design feature of the combination flasher
allows it to "sense" that a turn signal circuit or bulb is
not operating, and provide the driver an indication of
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