Chrysler 1998 Voyager Service Manual page 420

8H - 4 VEHICLE SPEED CONTROL SYSTEM
DIAGNOSIS AND TESTING (Continued)
Hex Code
23
OF
56
57
52
Check Engine Lamp will illuminate during engine operation if this Diagnostic Trouble Code was recorded.
Refer to Group 25, for further information and use-
age of the DRB scan tool and a more complete list of
Diagnostic Trouble Code.
SPEED CONTROL SLOWS DOWN BY ITSELF
Test vehicle speed sensor, refer to group 8E. If sen-
sor fails replace sensor, if it passes perform the fol-
lowing test:
(1) Perform the speed control switch test on the
DECEL switch, if it fails replace switch.
(2) If the switch passes, conduct the vacuum sup-
ply test.
(3) If it passes, conduct the servo vacuum test. If it
fails replace servo.
(4) If continuity, replace the PCM.
SPEED CONTROL ELECTRICAL TEST
Electronic speed control systems may be tested
using two different methods. One involves use of a
DRB. If this test method is desired, refer to the Pow-
ertrain Diagnostic Test Procedures for charging and
speed control system manual.
SPEED CONTROL DIAGNOSTIC TROUBLE CODES
DRB Scan Tool Display
No Vehicle Speed Sensor Signal
Speed Control Solenoid Circuits
MUX S/C Switch High
MUX S/C Switch Low
S/C Power Relay Or 12V Driver
Circuit
Description of Diagnostic Trouble
Code
No vehicle distance (speed) sensor
signal detected during road load
conditions.
An open or shorted condition
detected in the Speed Control
vacuum or vent solenoid circuits.
Speed Control switch input above
the maximum acceptable voltage.
Speed Control switch input below
the minimum acceptable voltage.
Malfunction detected with power
feed to speed control servo solnoids.
The other test method uses a volt/ohm meter. The
volt/ohm meter method is described in the following
tests.
If any information is needed concerning wiring,
refer to Group 8W, Wiring Diagrams (Fig. 2).
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.
When electrical connections are removed, corrosion
should be removed from electrical terminals and a
light coating of Mopar Multi-Purpose Grease, or
equivalent, applied. Inspect connectors for damage
terminals.
A poor connection can cause a complete or inter-
mittent malfunction and is also the only connection
in the circuit, that can not be tested. For this reason,
a loose connection may be misdiagnosed as a compo-
nent malfunction.
NS