Diagnosis And Testing - Road Test; Specifications - Torque; Cable Description; Operation - Chrysler 300M 2002 Service Manual

LH
SPEED CONTROL (Continued)

OPERATION

The Powertrain Control Module (PCM) first senses
that the speed control is set. If the set speed is
exceeded by more than 4 mph (6.5 km/hr) and the
throttle is closed, the PCM causes the transaxle to
downshift to THIRD gear. After downshifting, the
automatic speed control resumes normal operation.
To ensure that an upshift is appropriate after the set
speed is reached, the PCM waits until the speed con-
trol system opens the throttle at least 6 degrees
before upshifting to OVERDRIVE again.
If the driver applies the brakes, canceling auto-
matic speed control operation with the transaxle still
in THIRD gear, the PCM maintains this gear until
the driver opens the throttle at least 6 degrees to
avoid an inappropriate upshift. The upshift is also
delayed for 2.5 seconds after reaching the 6 degrees
throttle opening in anticipation that the driver might
open the throttle enough to require THIRD gear.
This will avoid unnecessary and disturbing transmis-
sion cycling. If the automatic speed control RESUME
feature is used after braking, the upshift is delayed
until the set speed is achieved to reduce cycling and
provide better response.

DIAGNOSIS AND TESTING - ROAD TEST

Perform a vehicle road test to verify reports of
speed control system malfunction. The road test
should include attention to the speedometer. Speed-
ometer operation should be smooth and without flut-
ter at all speeds.
Flutter in the speedometer indicates a problem
which might cause surging in the speed control sys-

SPECIFICATIONS - TORQUE

DESCRIPTION
Vacuum Resevoir Screws
Servo Mounting Bracket
Nuts
Servo Mounting Bracket
Bolts
Servo Mounting Nuts
CABLE
DESCRIPTION
The speed control servo cable is connected between
the speed control vacuum servo diaphragm and the
throttle body control linkage.
tem. The cause of any speedometer problems should
be corrected before proceeding. Refer to the Instru-
ment Cluster for speedometer diagnosis.
If a road test verifies an inoperative system, and
the speedometer operates properly, check for:
• A Diagnostic Trouble Code (DTC). If a DTC
exists, conduct tests per the Powertrain Diagnostic
Procedures manual.
• A misadjusted brake (stop) lamp switch. This
could also cause an intermittent problem.
• Loose or corroded electrical connections at the
servo. Corrosion should be removed from electrical
terminals and a light coating of Mopar Multipurpose
Grease, or equivalent, applied.
• Leaking vacuum reservoir.
• Loose or leaking vacuum hoses or connections.
• Defective one-way vacuum check valve.
• Secure attachment at both ends of the speed
control servo cable.
• Smooth operation of throttle linkage and throttle
body air valve.
• Conduct electrical test at PCM.
• Failed speed control servo. Do the servo vacuum
test.
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.
N·m
12
14
14
6.7
OPERATION
This cable causes the throttle control linkage to
open or close the throttle valve in response to move-
ment of the vacuum servo diaphragm.
SPEED CONTROL 8P - 3
Ft. Lbs.
8.8
10.3
10.3
–
In. Lbs.
106.2
123.9
123.9
60