Dodge 2000 DURANGO Service Manual page 499

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DIAGNOSIS AND TESTING
COMPASS MINI-TRIP COMPUTER
If the problem with the compass mini-trip com-
puter module is an "OC" or "SC" in the compass/ther-
mometer display, refer to Ambient Temperature
Sensor in the Diagnosis and Testing section of this
group. If the problem with the compass mini-trip
computer module is an inaccurate or scrambled dis-
play, refer to Self-Diagnostic Test in the Diagnosis
and Testing section of this group. If the problem with
the compass mini-trip computer module is incorrect
Vacuum Fluorescent Display (VFD) dimming levels,
use a DRB scan tool and the proper Diagnostic Pro-
cedures manual to test for the correct dimming mes-
sage inputs being received from the instrument
cluster over the Chrysler Collision Detection (CCD)
data bus. If the problem is a no-display condition,
use the following procedures. For complete circuit
diagrams, refer to Overhead Console in the Con-
tents of Group 8W - Wiring Diagrams.
(1) Check the fused ignition switch output (run/
start) fuse in the junction block. If OK, go to Step 2.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the junction block. If OK,
go to Step 3. If not OK, repair the open fused ignition
switch output (run/start) circuit to the ignition switch
as required.
(3) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the overhead console. Check for continuity
between the ground circuit cavities of the roof wire
harness connector for the overhead console and a
good ground. There should be continuity. If OK, go to
Step 4. If not OK, repair the open ground circuit to
ground as required.
(4) Connect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output (run/start)
circuit cavity of the roof wire harness connector for
the overhead console. If OK, refer to Self-Diagnos-
tic Test in the Diagnosis and Testing section of this
group for further diagnosis of the compass mini-trip
computer module and the CCD data bus. If not OK,
repair the open fused ignition switch output (run/
start) circuit to the junction block fuse as required.
SELF-DIAGNOSTIC TEST
A self-diagnostic test is used to determine that the
compass mini-trip computer module is operating
properly electrically. Initiate the self-diagnostic test
as follows:
OVERHEAD CONSOLE SYSTEMS
(1) With the ignition switch in the Off position,
simultaneously depress and hold the Step button and
the U.S./Metric button.
(2) Turn the ignition switch to the On position.
(3) Continue to hold both buttons depressed until
the compass mini-trip computer module enters the
display segment test. In this test, all of the Vacuum
Fluorescent Display (VFD) segments are lighted
while the compass mini-trip computer module per-
forms the following checks:
a. Microprocessor compass circuit test
b. Non-volatile memory read/write test
c. Microprocessor ROM verification test
d. CCD communications test.
(4) Following completion of these tests, the com-
pass mini-trip computer will return to normal opera-
tion or display one of two messages: "FAIL" or "CCd."
Respond to these test results as follows:
a. If no test result message is displayed, but com-
pass mini-trip computer operation is still improper,
the use of a DRB scan tool and the proper Diagnostic
Procedures manual are required for further diagno-
sis.
b. If the "FAIL" message is displayed, the compass
mini-trip computer module is faulty and must be
replaced.
c. If the "CCd" message is displayed, the use of a
DRB scan tool and the proper Diagnostic Procedures
manual are required for further diagnosis.
d. If any VFD segment should fail to light during
the display segment test, the compass mini-trip com-
puter module is faulty and must be replaced.
(5) If all tests are passed, or if the ignition switch
is turned to the Off position, the compass mini-trip
computer module will automatically return to normal
operation.
NOTE: If the compass functions, but accuracy is
suspect, it may be necessary to perform a variation
adjustment. This procedure allows the compass
unit to accommodate variations in the earth's mag-
netic field strength, based on geographic location.
Refer to Compass Variation Adjustment in the Ser-
vice Procedures section of this group.
NOTE: If the compass reading has blanked out, and
only "CAL" appears in the display, demagnetizing
may be necessary to remove excessive residual
magnetic fields from the vehicle. Refer to Compass
Demagnetizing in the Service Procedures section of
this group.
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