1994 JEEP CHEROKEE Service Repair Manual

8H - 4 VEHICLE SPEED CONTROL SYSTEMJ

TEST PROCEDURES
INDEX
page page
Checking for Diagnostic Trouble Code......... 5
Electrical Tests at Powertrain Control Module.... 6
Electrical Tests at Servo.................... 5
Inoperative System........................ 5
Operational Check (Road Test)............... 7
Road Test............................... 5Speed Control Switch (Turn Signal Lever) Test . . . 7
Stop Lamp Speed Control Switch Test......... 7
Vacuum Supply Test....................... 7
Vehicle Speed Control System Electrical Tests . . . 5
Vehicle Speed Sensor Test.................. 5
ROAD TEST
Refer to Operational Check (Road Test) section to
verify reports of speed control system malfunction.
INOPERATIVE SYSTEM
Road test vehicle to verify reports of speed control
system malfunction. An inspection should be made
for loose electrical and vacuum connections at the
servo.
Check for correct installation of the vacuum check
valve in the hose from servo to vacuum source. The
word VAC on the valve must point toward the vac-
uum source.
Corrosion should be removed from electrical termi-
nals and a light coating of Mopar MultiPurpose
Grease, or equivalent, applied.
Inspection also should be made to verify that both
ends of the speed control cable are securely attached.
CHECKING FOR DIAGNOSTIC TROUBLE CODE
(1) When trying to verify a speed control system
electronic malfunction use a DRB scan tool to find
the cause (refer to Powertrain Diagnostic Procedures
manual).
If DRB is not available, the Diagnostic Trouble
Code (DTC) may be determined with the following
method:
(a) With key inserted in ignition switch, cycle
switch to ON position 3 times. On third cycle, leave
switch in ON position.
(b) After switch has been cycled 3 times, observe
Malfunction Indicator Lamp (CHECK ENGINE)
on instrument cluster. If a DTC is present, the code
will be displayed in a series of flashes representing
digits. Three flashes in rapid succession, a slight
pause, then 4 flashes in rapid succession would in-
dicate DTC 34.
(2) If a DTC 34 is observed, perform tests in the
sections Electrical Tests at Servo and Electrical Tests
at Powertrain Control Module.
If a DTC 15 is observed, perform test for a faulty
vehicle speed sensor.
(3) Correct any problems found when performing
these tests and recheck for DTC if changes were
made.
VEHICLE SPEED SENSOR TEST
For testing of the vehicle speed sensor and related
components, refer to Powertrain Diagnostic Proce-
dures manual.
VEHICLE SPEED CONTROL SYSTEM ELECTRICAL
TESTS
Vehicle speed control systems may be tested using
two different methods. One involves use of a DRB
scan tool. If this test method is desired, refer to Pow-
ertrain Diagnostic Procedures manual.
The other test method uses a voltmeter. The volt-
meter method is described in the following tests.
If any information is needed concerning wiring, re-
fer to Section 8W - Wiring Diagrams.
CAUTION: When test probing for voltage or conti-
nuity at electrical connectors, care must be taken
not to damage connector, terminals, or seals. If
these components are damaged, intermittent or
complete system failure may occur.
ELECTRICAL TESTS AT SERVO
(1) Turn ignition switch to the ON position. With
speed control switch in the ON position, setup a volt-
meter to read battery voltage and connect negative
lead to a good chassis ground.
(2) Disconnect 4-way connector going to servo
(Figs. 2 and 3). Blue wire with red tracer of main
harness 4-way connector should read approximately
battery voltage. If not, check for loose connections,
brake switch adjustment or, repair main harness as
necessary.
(3) Connect a jumper wire between male and fe-
male terminals of blue wire with red tracer. The
other 3 male terminals from servo should show bat-
tery voltage. If not, replace servo.
(4) Using an ohmmeter, connect one lead to a good
body ground. Touch other lead to black wire terminal
in 4-way connector of main harness. Meter should
show continuity. If not, repair ground circuit as nec-
essary.
JVEHICLE SPEED CONTROL SYSTEM 8H - 5

ELECTRICAL TESTS AT POWERTRAIN CONTROL
MODULE
(1) Unplug 60-way connector from Powertrain Con-
trol Module, located on drivers side fender (Fig. 4).
(2) Connect negative lead of voltmeter to a good
body ground near module.
(3) For the following tests, ignition switch must be
in ON position. Refer to Fig. 5 for controller terminal
locations. Touch positive lead of voltmeter to termi-
nal in cavity number 33. With speed control switch
in OFF position, voltmeter should read 0 volts. With
speed control switch in ON position, voltmeter should
read battery voltage. If not, repair main harness as
necessary.(4) Touch positive lead of the voltmeter to terminal
in cavity number 53. As in step (3), voltmeter should
read 0 volts with switch in OFF position and battery
voltage with switch in ON position.
(5) Touch positive lead of voltmeter to terminal in
cavity number 48. With speed control switch in OFF
position, voltmeter should read 0 volts. With switch
in ON position, voltmeter should read battery volt-
age. Pressing SET button should cause voltmeter to
change from battery voltage to 0 volts for as long as
the switch is held. If not, perform the speed control
switch test. If the switch is not at fault, then check
main harness and repair as necessary.
(6) Touch positive lead of voltmeter to terminal in
cavity number 50. The voltmeter should read 0 volts
with speed control switch in either OFF or ON posi-
tion. With switch in either RESUME or SET posi-
tion, voltmeter should read battery voltage. If not,
perform the speed control switch test. If the switch is
not at fault, then check main harness and repair as
necessary.
(7) Touch positive lead of voltmeter to terminal in
cavity number 49. The voltmeter should read 0 volts
with switch in OFF position. With switch in ON po-
sition, voltmeter should read battery voltage. The
voltmeter will continue to read battery voltage when
either the SET or RESUME switch is pressed. If not,
Fig. 2 Servo And Harness ConnectorÐLeft Hand
Drive
Fig. 3 Servo And Harness ConnectorÐRight Hand
Drive
Fig. 4 Powertrain Control Module and Connector
Location
Fig. 5 Powertrain Control Module 60-Way Connector
Shown from Terminal End
8H - 6 VEHICLE SPEED CONTROL SYSTEMJ

perform the speed control switch test. If switch is not
at fault, then check main harness and repair as nec-
essary.
(8) Using an ohmmeter, connect one lead to a good
body ground and touch other lead to terminal in cav-
ity number 29. With brake pedal released, meter
should show continuity. When pedal is depressed,
meter should show open circuit.
SPEED CONTROL SWITCH (TURN SIGNAL LEVER)
TEST
STOP LAMP SPEED CONTROL SWITCH TEST
(1) Disconnect double connector at switch pigtail
and connect a 12 volt source to either terminal. Con-
nect a test lamp between other terminal and a good
ground. The test lamp should be on when brakepedal is in normal position. The test light should go
off when brake pedal is depressed approximately 3/8
of an inch.
(2) If test lamp does not respond properly, the stop
lamp switch is defective or out of adjustment.
(3) Stop lamp switch adjustment is detailed in
Group 5 - Brakes section of this manual.
VACUUM SUPPLY TEST
(1) Disconnect vacuum hose at servo or vacuum
reservoir and install a vacuum gauge in hose (Fig.
6).
(2) Start engine and observe gauge at idle. Vac-
uum gauge should read at least ten inches of mer-
cury.
(3) If vacuum does not meet this requirement,
check for vacuum leaks or poor engine performance.
OPERATIONAL CHECK (ROAD TEST)
The following sequential checks are performed with
the speed switch ON and vehicle speed faster than 35
mph:
(1) Press the SET button in end of multi-function
lever. Vehicle should maintain set speed.
(2) Hold SET button in, and remove foot from ac-
celerator. Vehicle should coast to a slower speed.
(3) Release SET button. Speed control will engage
and hold a slower speed, provided the speed remains
above 35 mph.
JVEHICLE SPEED CONTROL SYSTEM 8H - 7

(4) Slide speed switch to RESUME/ACCEL and
hold it there. Vehicle should accelerate.
(5) Release speed switch back to ON. Vehicle will
hold the new faster speed, if SET speed button has
been pressed.
(6) Tap brake pedal. Vehicle will decelerate.
If vehicle has a manual transmission, repeat test,
but depress the clutch pedal.
(7) Slide speed switch momentarily RESUME/AC-
CEL. Vehicle will accelerate to former set speed.
(8) While cruising, accelerate, then remove foot
from accelerator. Vehicle will coast back to set speed.
(9) While speed control is engaged, tap SET but-
ton. Vehicle speed will increase 2 mph for each time
SET button is tapped.
Fig. 6 Vacuum Gauge Test
8H - 8 VEHICLE SPEED CONTROL SYSTEMJ

SERVICE PROCEDURES
INDEX
page page
Servo Cable Replacement................... 9
Speed Control Servo Replacement............ 9Speed Control Switch Replacement............ 9
SPEED CONTROL SERVO REPLACEMENT
REMOVAL
(1) Disconnect vacuum hose at servo (Figs. 1 and
2).
(2) Disconnect electrical connector at servo.
(3) Remove 2 nuts from cable sleeve.
(4) Pull speed control cable away from servo to ex-
pose cable retaining clip.
(5) Remove clip attaching cable to servo.
(6) Pull servo away from mounting bracket.
INSTALLATION
(1) Insert servo studs through holes in servo
mounting bracket.
(2) With throttle blocked to full open position,
align hole in cable sleeve with hole in servo pin and
install retaining clip.
(3)
Insert servo studs through holes in cable sleeve.
(4) Install 2 attaching nuts and tighten to 6 Nzm
(50 in. lbs.).
(5) Connect vacuum hose to servo.
(6) Connect electrical connector to servo terminals.
SERVO CABLE REPLACEMENT
CAUTION: Use finger pressure only to remove the
speed control cable connector at the bell crank. Pli-
ers or screwdriver can break connector requiring
complete cable replacement.
(1) Using finger pressure only, remove speed con-
trol cable connector at bell crank by pushing connec-
tor off the bell crank (Fig. 3). DO NOT try to pull
connector off perpendicular to the bell crank.
(2) Squeeze tabs on speed control cable and push
out of locking plate (Fig. 4).
(3) Pull cable out of cable guide.
(4) Remove 2 nuts and cable housing from servo.
(5) Release cable clip from servo cable and remove
servo cable.
(6) To install, reverse the removal procedure.
SPEED CONTROL SWITCH REPLACEMENT
(1) Disconnect negative cable from battery.
(2) Remove horn button with a push and turn mo-
tion.
(3) Remove horn button components (Fig. 5).
(4) Turn ignition switch to LOCK position and re-
move steering wheel nut and washer.
(5) Scribe an alignment mark on the steering in
line with the mark already existing on the end of the
steering column.
Fig. 2 Speed Control ServoÐRight Hand Drive
Fig. 1 Speed Control ServoÐLeft Hand Drive
JVEHICLE SPEED CONTROL SYSTEM 8H - 9

(6) Remove vibration damper from the steering col-
umn hub, if equipped.(7) Remove steering wheel using a steering wheel
puller.
WARNING: TO REMOVE THE STEERING SHAFT
SNAP RING IN THE FOLLOWING STEP, THE LOCK-
PLATE MUST BE COMPRESSED. DO NOT ATTEMPT
TO REMOVE THE LOCKPLATE WITHOUT COM-
PRESSOR TOOL C4156 AS THE LOCKPLATE IS UN-
DER HEAVY SPRING TENSION.
(8) Compress lockplate with compressor tool
C4156.
(9) Remove steering shaft snap ring (Fig. 6). Dis-
card snap ring. It is not reusable.
(10) Remove compressor tool.
(11) Remove lockplate, cancelling cam, and upper
bearing preload spring.
(12) Remove horn button components from cancel-
ing cam.
(13) Remove screw and hazard warning switch
knob.
(14) Remove actuator arm attaching screw.
(15) Remove turn signal switch attaching screws.
(16) Unplug speed control switch connector.
(17) Pull speed control harness out of the column.
(18) Insert ignition key in lock cylinder and turn
key to ON position.
(19) Remove key warning buzzer switch and re-
taining clip with a paper clip inserted below retainer
so that retainer is flattened (Fig. 7).
Do not attempt to remove buzzer switch and
clip separately. The clip could fall into the col-
umn jacket.
Fig. 3 Remove Bell Crank Connector
Fig. 4 Remove/Install Speed Control Cable to
Locking Plate
Fig. 5 Steering Wheel Removal/Installation
8H - 10 VEHICLE SPEED CONTROL SYSTEMJ

(20) Remove ignition lock cylinder retaining screw
and pull lock cylinder out of column housing (Fig. 8).
(21) Remove screws that attach housing and
shroud assembly to column jacket and carefully re-
move housing and shroud assembly (Fig. 9).
Do not let dimmer switch rod, lock pin or lock
rack fall out.
(22) Remove turn signal/wiper lever by pulling it
straight out of column.(23) Remove wiper switch cover from back of hous-
ing and shroud assembly (Fig. 10). If equipped with
column shift, remove screw holding the cover on.
(24) Remove pivot screw from housing and remove
wiper switch.
(25) Install a new switch and switch cover.
(26) Push on dimmer switch rod to make sure it is
connected then carefully position housing and shroud
assembly to column (Fig. 11).
Fig. 6 Lockplate Removal
Fig. 7 Buzzer Switch Removal
Fig. 8 Lock Cylinder Removal/Installation
Fig. 9 Steering Column Housing
Removal/Installation
JVEHICLE SPEED CONTROL SYSTEM 8H - 11