
Dodge Durango
Service Manual
Speed Control System » 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. Speedometer
operation should be smooth and without flutter
at all speeds.
Flutter in the speedometer indicates a problem
which might cause surging in the speed control system.
The cause of any speedometer problems should
be corrected before proceeding. Refer to Group 8E,
Instrument Panel and Gauges for speedometer diagnosis.
If a road test verifies a system problem and the
speedometer operates properly, check for:
- A Diagnostic Trouble Code (DTC). If a DTC
exists, conduct tests per the Powertrain Diagnostic
Procedures service manual.
- A misadjusted brake (stop) lamp switch. This
could also cause an intermittent problem.
- Loose, damaged 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 of both ends of the speed control
servo cable.
- Smooth operation of throttle linkage and throttle
body air valve.
- Failed speed control servo. Do the servo vacuum
test.
CAUTION: When test probing for voltage or continuity
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.
More about «Diagnosis and testing»:
Road test