Grand Cherokee 2WD V8-4.7L VIN J (2004)
sensor (ATS).
The ATS is a variable resistor that operates on a 5-volt reference signal circuit hardwired from the BCM. The resistance in the ATS changes as the
outside temperature rises or falls. The BCM senses the change in reference voltage through the ATS resistor. Based on the resistance of the ATS, the
BCM is programmed to correspond to a specific temperature. The BCM stores and filters the ambient temperature data and transmits this data to the
EVIC via the PCI Bus. The ATS cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
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 BCM, and the
EVIC display.
If the EVIC display indicates 54° C (130° F) or the ATS sense circuit is shorted to ground, the temp display will be 54° C (130° F) to indicate a
SHORT circuit condition.
If the EVIC display indicates -40° C (-40° F) or the ATS sense circuit is open, the temp display will be -40° C (-40° F) to indicate an OPEN circuit
condition.
If there is an OPEN or SHORT circuit condition, it must be repaired before the EVIC VFD can be tested.
The ATS is supported by the BCM. Ambient Temperature Sensor DTCs will be recorded in the BCM. The ATS can be diagnosed using the following
Sensor Test. Test the ATS circuits using the diagnostics in the Body Diagnostic Procedures Manual. If the EVIC passes the self test, and the ATS, the
circuits, and PCI bus communications are confirmed to be OK, but the EVIC temperature display is inoperative or incorrect, replace the BCM.
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:
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0° C (32° F) Sensor Resistance = 29.33 - 35.99 Kilohms
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10° C (50° F,¯ Sensor Resistance = 17.99 - 21.81 Kilohms
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20° C (68° F) Sensor Resistance = 11.37 - 13.61 Kilohms
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25° C (77° F) Sensor Resistance = 9.12 - 10.86 Kilohms
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30° C (86° F) Sensor Resistance = 7.37 - 8.75 Kilohms
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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.
HOMELINK(R) UNIVERSAL TRANSMITTER
If equipped, the HomeLink(R) Universal Transmitter is integrated into the overhead console. For added security it will operate home security systems
that use coded signals known generically as Rolling Codes. The overhead console display provides visual feedback to the driver, indicating which
HomeLink¨ transmitter channel button is being pressed. The HomeLink¨ can learn and store up to three separate transmitter radio frequency codes to
operate garage door openers, security gates, and security lighting. The HomeLink¨ buttons are marked with one, two, or three dots.
Exterior Lighting System
EXTERIOR LIGHTING BATTERY SAVER
The BCM monitors the status of and controls the park lamp, head lamp and fog lamp relay's. If any exterior lamps are left on after the ignition is turned
off, the BCM will turn them off after 8 minutes.
HEADLAMP DELAY
The headlamp time delay operates when the ignition switch is turned off while the headlamps are still on. This feature is customer programmable to
provide a 30, 60 or 90 second time delay before turning off the headlamps. This feature can also be disabled.
HEADLAMP SWITCH
The headlight switch on WJ vehicles uses a multiplexed (MUX) circuit to the BCM. The BCM will then control the park lamp, low/high head lamp and
fog lamp relay's based on this input.
FOG LAMP CONTROL
The body control module controls the operation of the fog lamp relay which controls the fog lamps. The fog lamps can only be on if the park or low
beam headlamps are on. If the high beams are turned on, the fog lamps will automatically be turned off.
