Jeep 200 Cherokee, Service Manual

Page: 454 / 2119

TURN SIGNAL CANCELLING CAM
DESCRIPTION
The turn signal cancelling cam is concealed within
the steering column below the steering wheel. The
turn signal cancelling cam consists of two lobes that
are integral to the lower surface of the clockspring
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 and speed control 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 station-
ary. 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
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 a wire har-
ness connector which is secured to the diagnostics
splice block bracket outboard of the steering column
opening underneath the instrument panel. The com-
bination flasher cannot 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
9
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
XJ
TURN SIGNAL AND HAZARD WARNING SYSTEMS 8J - 3
DESCRIPTION AND OPERATION (Continued)