Chrysler PT Cruiser. Manual - part 5

3.3.2

COMPASS CALIBRATION

NOTE: Upon installation of a new overhead
console, with the ignition ON, “CAL” will be
illuminated in the display but the compass
will not calibrate for 30 ignition cycles or 15
starts, OR until manually calibrated. For this
reason, manual calibration of the compass is
recommended

after

any

replacement

appearance of the compass/temp display
being “locked-up.”

MANUAL CALIBRATION

After any replacement or the appearance of a

“locked-up” condition, you must calibrate the com-
pass. Follow these instructions in order to ensure
correct compass calibration:

•

Drive the vehicle to an area away from any large
metal objects or overhead power lines.

•

Ensure that the proper variance zone is selected.
See “Setting Magnetic Zone Variance.”

•

With the engine running, depress and hold the
STEP button for 10 - 15 seconds.

•

ZONE will appear in display, then CAL.

•

Release the STEP button within 2 seconds of CAL
illuminating.

•

CAL is displayed.

•

Drive slowly, less than 5 MPH (8 KPH) in 3
complete 360 degree circles.

•

CAL will stay illuminated to alert the driver that
the Compass/Temperature Module is in the cali-
bration mode.

•

After calibration, the CAL will turn off.

AUTO CALIBRATION MODE

During normal vehicle operation, the Compass/

Temperature Module will continuously update the
compass calibration to compensate for changes in
the vehicle’s magnetic field. If the Compass/
Temperature Module appears to be “locked- up” or
the compass displays false indications, the vehicle
may need to be demagnetized. Refer to Demagne-
tizing Procedure in the Service Manual.

3.3.3

OUTSIDE TEMPERATURE

NOTE: Engine temperature or the vehicle
experiencing a “hot soak” condition can
increase the temperature near the ambient
temperature

sensor.

The

displayed

temperature may appear to update slowly
until the vehicle is driven and the compass
performs directional updates.

The displayed outside temperature information is

stored within the compass/temp module. When the
Compass/Temperature Module is first powered up,
it retrieves the temperature data from the module
memory. The memory temperature is compared
with the temperature received from the ambient
temperature sensor (ATS). The colder of the two
temperatures is displayed.

TEMPERATURE UPDATE - WARM

On power up, when the outside temperature

sensed by the ATS is warmer than the temperature
stored in the module memory, the Compass/
Temperature Module will update the displayed tem-

GENERAL INFORMATION

perature to the outside air temperature within 30
seconds after it has detected that the vehicle has
been moving for 2 minutes.

TEMPERATURE UPDATE - COLD

On power up, when the outside air temperature

sensed by the ATS is colder than the stored memory
temperature, the Compass/Temperature Module
will update the displayed temperature to the out-
side temperature at a rate of -1°F every 2 seconds,
regardless if the vehicle is moving or not.

EXTREME

TEMPERATURE

OPEN

SHORT CIRCUIT CONDITION

If the measured outside temperature is more

than 60°C (140°F) or the ATS sense circuit is
shorted to ground, the temp display will be 60°C
(140°F) to indicate a short circuit condition.

If the measured outside temperature is less than

-45°C (-49°F) or the ATS sense circuit is open, the
temp display will be -45°C (-49°F) to indicate an
open circuit condition.

3.3.4

AMBIENT TEMPERATURE SENSOR

DESCRIPTION

The ambient air temperature is monitored and

displayed by the Compass/Temp Module. The
Compass/Temperature Module receives a hardwire
input from the ambient temperature sensor (ATS).
The ATS is mounted on the center support brace in
front of the A/C condenser, behind the front grille.

The ATS cannot be adjusted or repaired and, if

faulty or damaged, it must be replaced.

OPERATION

The ATS is a variable resistor that operates on a

5-volt reference signal circuit hardwired from the
Compass/Temperature Module. The resistance in
the ATS changes as the outside temperature rises or
falls. The Compass/Temperature Module senses the
change in reference voltage through the ATS resis-
tor. Based on the resistance of the ATS, the
Compass/Temperature Module is programmed to
correspond to a specific temperature. The Compass/
Temperature Module then displays the proper am-
bient temperature.

3.3.5

DIAGNOSIS AND TESTING

SELF-CHECK DIAGNOSTICS

1. With the ignition switch in the OFF position,

depress and hold the STEP button.

2. Turn the ignition switch to the ON position and

release the STEP button.

3. All of the VFD segments will illuminate for 2-4

seconds. Check for segments that do not illumi-
nate or illuminate all the time.

4. The self-check is complete when an F (FAIL), or

a P (PASS) is displayed. If an F is displayed, the
overhead

console

must

replaced.

The

Compass/Temperature Module will not display
an F for a VF segment that does not illuminate.

5. To exit the self-check mode, depress the STEP

button or cycle the ignition switch and the
Compass/Temperature Module will return to
normal operation.

AMBIENT TEMPERATURE SENSOR

The outside temperature function is supported by

the ambient temperature sensor (ATS), a signal and
ground circuit hardwired to the compass/temp mod-
ule, and the display.

If the display indicates 60°C (140°F) or the ATS

sense circuit is shorted to ground, the temp display
will be 60°C (140°F) to indicate a SHORT circuit
condition.

If the display indicates -45°C (-49°F) or the ATS

sense circuit is open, the temp display will be -45°C
(-49°F) to indicate an OPEN circuit condition.

If there is an OPEN or SHORT circuit condition,

it must be repaired before the VF display can be
tested.

The ATS can be diagnosed using the following

Sensor Test. Test the ATS circuits using the diag-
nostics in the Body Diagnostic Procedures Manual.
If the ATS and the circuits are confirmed to be OK,
but the temperature display is inoperative or incor-
rect, replace the Compass/Temperature Module.

AMBIENT TEMPERATURE SENSOR TEST

1. Turn the ignition OFF.

2. Disconnect and isolate the battery negative ca-

ble (Fig. 3).

3. Disconnect the ATS harness connector.

4. Measure the resistance of the ATS using the

following min/max values:

•

0° C (32° F)
Sensor Resistance = 29.33 - 35.99 Kilohms

•

10° C (50° F)
Sensor Resistance = 17.99 - 21.81 Kilohms

•

20° C (68° F)
Sensor Resistance = 11.37 - 13.61 Kilohms

•

25° C (77° F)
Sensor Resistance = 9.12 - 10.86 Kilohms

•

30° C (86° F)
Sensor Resistance = 7.37 - 8.75 Kilohms

•

40° C (104° F)
Sensor Resistance = 4.90 - 5.75 Kilohms

The sensor resistance should read between these

min/max values. If the resistance values are not
OK, replace the Sensor.

GENERAL INFORMATION

3.4

COMPASS/TEMPERATURE MIRROR

DESCRIPTION

The optional Compass/Temperature Mirror has a

vacuum fluorescent (VF) display that is integrated
into the rear view mirror. The Compass/Temp Mir-
ror includes the compass/temperature display and
two map/reading lamps. This display provides the
outside temperature and one of eight compass head-
ings to indicate the direction the vehicle is facing.
The Compass/Temp Mirror displays the compass
heading and the outside temperature at the same
time. The Ambient Temperature Sensor monitors
the outside temperature and is hardwired to the
PCM. The Compass/Temp Mirror also receives and
transmits data on the PCI Bus.

OPERATION

The Compass/Temp Mirror incorporates 2 read-

ing lamp buttons with the STEP button and the
Zone/Calibration button features activated by hold-
ing a button for a specified time period. The STEP
button provides the selections between English and
Metric. The Zone/Cal button provides the selection
to change the compass zone or to calibrate the
compass. The reading lamp buttons also cycle the
reading lamps on or off.

The STEP button (right reading lamp button)

operates a momentary contact switch which pro-
vides input to the Compass/Temp Mirror in one of
the following four modes:

•

To toggle the right reading lamp on and off
upon release of the button.

•

To select degrees in F (Fahrenheit) for the
temperature display.

•

To select degrees in C (Celsius) for the temper-
ature display.

•

To turn off the compass/temperature display.

ENGLISH / METRIC / OFF MODE

With the ignition in the ON position, pressing

and holding the STEP button (right reading lamp
button) for 5-10 seconds will toggle the display
between English and Metric. The Compass/Temp
Mirror stores the selected display mode in memory
upon releasing the button during the 5-10 seconds.

Pressing and holding the STEP button for 10-15

seconds will turn the display OFF upon releasing
the button during the 10-15 seconds.

Each time the temperature mode is changed to F°

or C°, the Compass/Temp Mirror stores the new
mode in memory. The selected English or Metric
mode is recalled after the ignition is cycled. The
display OFF mode is not recalled after the ignition
is cycled. The Compass/Temp Mirror will power up
and display the temperature mode (F° or C°) that
was last selected.

CALIBRATION / ZONE MODE

Refer to the Zone Variance Map. With the ignition

in the ON position, pressing and holding the Zone/
Cal button (left reading lamp button) for 5-10
seconds will illuminate ZONE in the display. Re-
leasing the button while ZONE is illuminated will
enter the compass into the Zone Setting mode. The
Compass/Temp Mirror will illuminate the Zone
Variance number 1 to 15 that is stored in memory.
While ZONE is displayed; momentarily pressing
the Zone/Cal button advances the zone to the next
higher zone. When the desired zone number is
displayed, do not press the Zone/Cal button again.
After 5 seconds, the Zone Variance number will be
stored in the module memory.

With the ignition in the ON position, pressing

and holding the Zone/Cal button for 10-15 seconds
will toggle the CAL (calibration) mode between on
and off. Releasing the button while CAL is dis-
played enters the compass into the calibration
mode. See “First Time Calibration”, “Manual Cali-
bration”, and “Continuous Calibration”.

Pressing and holding the Zone/Cal button for

15-20 seconds and then releasing will exit the CAL
mode and toggle the display to the current state of
compass/temperature mirror use; OFF, Compass/
Temperature F°, or Compass/Temperature C°.

Pressing and holding the Zone/Cal button for

20-25 seconds will enter the CTM into the self-
check diagnostic mode upon releasing the button.

Holding the Zone/Cal button for longer than 25

seconds will cause the display to return to its
current state with no changes.

SETTING COMPASS ZONE

The compass has a default zone of 8. Refer to the

Zone Variance Map to determine the correct zone
number. The correct compass Zone selection is crit-
ical to proper compass operation. With the ignition
in the ON position, pressing the Zone/Cal button
(left reading lamp button) for 5-10 seconds and then
releasing while ZONE is illuminated enters the
compass into the Zone display mode. In the Zone
display mode, ZONE will be illuminated instead of
the temperature. The current Zone number, 1
through 15 will be displayed. While ZONE is illu-
minated; momentarily pressing the Zone/Cal but-
ton advances the zone to the next higher zone.
When the desired zone number is displayed, do not
press the Zone/Cal button again. After 5 seconds,
the Zone Variance number will be stored in the
module memory.

FIRST TIME CALIBRATION

A new Compass/Temp Mirror is shipped in a first

time calibration mode. CAL is illuminated when the
Compass/Temp Mirror is first powered up. The first
time calibration mode can not be exited until the

GENERAL INFORMATION

first time calibration process is completed. The CAL
icon will remain illuminated to alert the driver that
the Compass/Temp Mirror is operating in the CAL
mode. Move the vehicle to an area away from large
metallic objects or overhead power lines. While CAL
is illuminated in the display the vehicle must be
driven in 3 complete 360 degree circles at less than
5 MPH (8 KPH). The compass will calibrate; CAL
will turn off, and then resume normal operation.

MANUAL CALIBRATION

With the ignition in the ON position, pressing

and holding the Zone/Cal button (left reading lamp
button) for 10-15 seconds will toggle the display to
CAL. Releasing the button within the 10-15 second
duration will enter the compass into the calibration
mode. CAL will remain illuminated until the cali-
bration is complete or is toggled off by pressing the
Zone/Cal button. Move the vehicle to an area away
from large metallic objects or overhead power lines.
While CAL is illuminated in the display the vehicle
must be driven in 3 complete 360 degree circles at
less than 5 MPH (8 KPH). The compass will cali-
brate; CAL will turn off, and then resume normal
operation.

CONTINUOUS CALIBRATION

During normal operation, the Compass/Temp

Mirror will continuously update the compass cali-
bration to adjust for gradual changes in the vehi-
cle’s magnetic remnant field. If the vehicle is sub-
jected to high magnetic influences, the compass
may appear to indicate false headings or appear
unable to be calibrated. If this occurs the vehicle

may need to be demagnetized. Refer to Demagne-
tizing Procedure in the Service Manual.

SELF- CHECK DIAGNOSTICS

With the ignition ON, the Compass/Temp Mirror

can perform a diagnostic self-check by pressing and
holding the Zone/Cal button (left reading lamp
button) for 20-25 seconds. The internal diagnostics
will sequence the following five tests:

1. VF segment display- Illuminates the segment

patterns one at a time for 1 second each as
follows: CAL; ZONE; N; NE; E; SE; S; SW; W;
NW; 0 through 9; C°; F°

2. CTM memory- ROM Checksum

3. CTM memory- RAM

4. CTM memory- EEPROM

5. Compass Test

During the self-check, if any of the internal tests

fail, the Compass/Temp Mirror will display an “F”
and the number of the test that failed. If more than
one test fails “FO” will be displayed. P- Pass or F-
Fail will be displayed until the Zone/Cal button (left
reading lamp button) is pressed and released or the
ignition is cycled. If all of the tests pass, the
Compass/Temp Mirror will display “P”. A VF seg-
ment that fails to illuminate will not cause the
Compass/Temp Mirror to display an “F”. If any
segment fails to illuminate or the Compass/Temp
Mirror displays “F”, the Compass/Temp Mirror
must be replaced.

To exit self-check diagnostics, press and release

the Zone/Cal button or cycle the ignition to return to
normal compass/temp operation.

GENERAL INFORMATION

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