AMBIENT TEMPERATURE SENSOR FAULT
CODES
The outside temperature function is supported by
the ambient temperature sensor (ATS), a signal and
ground circuit hardwired to the FCM or the PCM,
and the CMTC display.
If the CMTC display indicates 54°C (130°F) or the
ATS sense circuit is open, the temp display will be
54°C (130°F) to indicate an OPEN circuit condition.
If the CMTC display indicates -40°C (-40°F) or
theATS sense circuit is shorted to ground, the temp
display will be -40°C (-40°F) to indicate a SHORT
circuit condition.
If there is an OPEN or SHORT circuit condition,
it must be repaired before the CMTC VFD can be
tested.
The ATS is supported by the FCM or PCM.
Ambient Temperature Sensor DTCs will be re-
corded in the FCM or PCM. The ATS can be diag-
nosed using the following Sensor Test. Test theATS
circuits using the diagnostics in the Body Diagnos-
tic Procedures Manual. If the CMTC passes the self
test, and the ATS, the circuits, and PCI bus com-
munications are confirmed to be OK, but the CMTC
temperature display is inoperative or incorrect,
replace the FCM or PCM as required.
AMBIENT TEMPERATURE SENSOR TEST
1. Turn the ignition OFF.
2. Disconnect the ATS harness connector.
3. 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.
HOMELINKt UNIVERSAL TRANSMITTER
If equipped, the HomeLinkt Universal Transmit-
ter is integrated into the overhead console. For
added security it will operate home security sys-
tems that use coded signals known generically as
Rolling Codes. The overhead console display pro-
vides visual feedbackto the driver, indicating which
HomeLinkt transmitter channel button is being
pressed. The HomeLinkt can learn and store up to
three separate transmitter radio frequency codes to
operate garage door openers, security gates, and
security lighting. The HomeLinkt buttons are
marked with one, two, or three dots. For complete
information, refer to Universal Transmitter in the
Service Manual or the Owner’s Manual.
3.5 DOOR AJAR SYSTEM
The door ajar state is used as an input for various
control modules on the vehicle. The DRBIIIt will
display the state of the door ajar switches in Inputs/
Outputs. It’s important to note, that when a door is
closed, the switch state on the DRBIIIt will show
OPEN, and when the door is open, the switch state
will show CLOSED. During diagnosis, if a door is
closed and the DRBIIIt displays the switch state as
CLOSED, it indicates a shorted door ajar circuit. If
the door is open and the DRBIIIt displays the
switch state as OPEN, it indicates an open door ajar
circuit.
3.6 ELECTRICALLY HEATED SYSTEMS
HEATED MIRROR RELAY
A button located on the HVAC control head con-
trols the Heated Mirror Relay, which is located in
the IPM. The HVAC control will ground the Heated
Mirror Relay Control circuit to energize this relay.
The relay control circuit is continuously monitored
for certain malfunctions that the HVAC will report
as DTCs.
3.7 EXTERIOR LIGHTING SYSTEM
The Instrument Cluster monitors the Headlamp
Switch and Multifunctions Switch on its MUX line.
The Instrument Cluster sends a PCI busmessage to
the Front Control Module (FCM) to actuate the
Headlamps ON when the ignition switch is ON and
when an open or short failure occurs on the head-
lamps switch input circuit to the instrument clus-
ter. If the exterior lamps are left ON and the
ignition switch OFF for more than 5 minutes, the
FCM will turn the exterior lamps off. This feature
prevents the battery from being discharged when
the Exterior Lamps have been left ON.
3.8 FRONT CONTROL MODULE
The Front Control Module (FCM) is a
microprocessor-based electrical control and inter-
face center located in the engine compartment.
When it is mated to the Power Distribution Center
(PDC), it is referred to as the Integrated Power
Module (IPM). The IPM, with its fuses and relays
provides power and signal distribution throughout
most of the vehicle. The FCM receives hard-wired
11
GENERAL INFORMATION
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