Chrysler RAM TRUCK 2500 1994 Service Manual page 457

8H - 8 VEHICLE SPEED CONTROL SYSTEM
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meter should read zero volts with the switch i n the
OFF position, and battery voltage with the switch i n
the ON position.
(5) Touch the positive lead of the voltmeter to the
terminal i n cavity number 48. With the speed control
switch i n the OFF position, the voltmeter should
read zero volts. With the switch i n the ON position,
the voltmeter should read battery voltage. Pressing
the SET button should cause the voltmeter to change
from battery voltage to zero volts for as long as the
switch is held. I f not, perform the speed control
switch test. I f the switch is not at fault, then check
the main harness and repair as necessary.
(6) Touch the positive lead of the voltmeter to the
terminal i n cavity number 50. The voltmeter should
read zero volts with the speed control switch i n ei­
ther the OFF or ON position. With switch i n either
RESUME or SET position, the voltmeter should read
battery voltage. I f not, perform the speed control
switch test. I f the switch is not at fault, then check
the main harness and repair as necessary.
(7) Touch the positive lead of the voltmeter to the
terminal i n cavity number 49. The voltmeter should
read zero volts with the switch i n the OFF position.
With the switch i n the ON position, the voltmeter
should read battery voltage. The voltmeter will con­
tinue to read battery voltage when either the SET or
RESUME switch is pressed. I f not, perform the speed
control switch test. I f the switch is not at fault, then
check the main harness and repair as necessary .
(8) Turn ignition switch OFF. Using an ohmmeter,
connect one lead to a good body ground and touch the
other lead to the terminal i n cavity number 29. With
the brake pedal released, the meter should show con­
tinuity. When the pedal is depressed, the meter
should show open circuit.
(9) DIESEL ONLY. The diesel engine PCM re­
quires a signal from the engine speed sensor to cav­
ity number 24. To diagnose the engine speed sensor,
refer to the appropriate Powertrain Diagnostic Proce­
dures manual.
VEHICLE SPEED CONTROL SWITCH TEST
To check the switch, remove the switch from its
mounting position. Refer to Service Procedures for
access to switch. Use an ohmmeter and refer to the
Switch Continuity Chart to determine i f continuity is
correct. I f there is no continuity at any one of the
switch positions, replace the switch.
STOP LAMP SWITCH TEST
(1) Remove the stop lamp switch from the mount­
ing bracket. Refer to Service Procedures - Stop Lamp
Switch.
(2) Disconnect switch from wiring harness.
(3) Using an ohmmeter, check switch continuity
(Fig. 5) as follows:
SPEED CONTROL SWITCH CONTINUITY
CHART
C O N N E C T O R TERMINAL E N D
JE El
SWITCH
SPEED CONTftOL SWITCH
CONTINUITY
mmnmsmmi
CONTINUITY K T W K N
OFF
PIN 1 A N D PIN 4
O N
PIN 1 A N D PIN 4
PIN 1 A N D PIN 2
PIN 2 A N D PIN 4
O N
AND
SET PIN 1 A N D PIN 2
O N A N D RESUME
PIN 1 A N D PIN 3
J948H-30
(a) With switch plunger released, there should be
continuity between pin 5 and pin 6.
(b) With switch plunger depressed, there should
be continuity between pin 1 and pin 2.
(c) With switch plunger still depressed, there
should be continuity between pin 3 and pin 4.
(4) I f the switch fails the above continuity tests, i t
is defective. Replace switch. I f switch is OK, reinstall
and check adjustment. Refer to Service Procedures -
Stop Lamp Switch for correct installation and adjust­
ment procedures.
VACUUM SUPPLY TEST
(1) Disconnect vacuum hose at the servo and in­
stall a vacuum gauge i n the hose.
(2) Start engine and observe gauge at idle. Vacuum
gauge should read at least ten inches of mercury.
(3) I f vacuum does not meet this requirement,
check for vacuum leaks or poor engine performance.
F o r diesel engine refer to Group 5 - Brakes
for vacuum pump diagnosis.
SPEED CONTROL CABLE ATTACHMENT
Attach the speed control cable to the throttle body
lever as follows:
(1) Open throttle lever to completely expose nail
head.