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Normal Operation
The audio system and DVD player are enabled when the key is in the RUN or ACCESSORY position. The speakers are powered by the audio unit and the subwoofer is powered by its own amplifier. The steering wheel controls send information to the audio unit allowing the driver to adjust various audio controls. The audio unit can contain an integral six disc CD changer (CDX6) or the vehicle can be equipped with one of the following audio units that is not repairable: M100C AM/FM cassette radio, M100CD AM/FM/CD, or DM100 AM/FM/CD/cassette (premium). The subwoofer is available with the CDX6 Audiophile option while the digital versatile disc (DVD) is available with the CDX6 and DM100.
Principles of Operation
When the audio unit is powered up a wake-up signal is sent to the subwoofer amplifier. Audio output signals are then sent continuously to the subwoofer amplifier. These signals are then amplified and sent to the speakers as a fluctuating AC voltage thus producing sound from the speakers. A fluctuating AC voltage audio signal is also sent to the remaining speakers, directly from the audio unit, to produce sound. The steering wheel controls are a multiplexed system that use different resistor values to produce different voltage levels on a single circuit. Each button that is pressed results in a unique voltage signal at the audio unit. This voltage signal is then interpreted by the audio unit as a distinct command. The audio unit has a self diagnostic mode that can be entered by pressing preset buttons 3 and 6 simultaneously. The DVD player sends fluctuating AC voltage audio output signals to the audio unit. These signals are then amplified by the audio unit and sent to the speakers.
Refer to RADIO (Explorer) or RADIO (Mountaineer) Wiring Diagrams for schematic and connector information.
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- Verify the customer concern.
- Visually inspect for obvious signs of mechanical and electrical damage.
- If the concern is visually evident, proceed to «SYMPTOM CHART»(ref-194057-S23541624582005092600000) .
- If the concern is not visually evident, proceed to speaker walk-around test and audio unit self-diagnostic mode.
When the key is in the ON position with the audio unit on, the display lights, the audio unit is operational, and the CD/cassette feature can be operated. The Speaker Walk Around Test can be carried out pressing Preset buttons 3 and 6 simultaneously.
The radio antenna receives AM and FM radio waves. The radio waves are sent to the audio unit through the radio antenna lead-in cable.
The radio suppression equipment reduces interference transmitted through the speakers by the engine ignition and electrical systems. When installing any new radio suppression equipment components, make sure that a good contact is made at all connections. Remove any paint or dirt from between a component and its ground. Tighten all connectors and screws securely according to torque specifications.
The audio unit directs the audio signals to the speakers through separate positive and negative circuits for each of the four audio channels: LF, RF, LR, and RR. The audio unit provides internal circuit protection for shorts to ground, shorts to B+ battery or shorts between any output circuits.
The audio unit directs the audio signals to the speakers through separate positive and negative circuits for each of the four audio channels: LF, RF, LR, and RR. The audio unit provides internal circuit protection for shorts to ground, shorts to B+ battery or shorts between any output circuits.
The subwoofer speakers are powered from a separate subwoofer amplifier. The START input circuit, 168 (RD/BK), carries out two functions; to turn on the subwoofer amplifier, and to indicate to the audio unit when the subwoofer output distortion signal reaches a damaging level. The audio unit then reduces the audio output signal to the subwoofer amplifier.
The START input circuit 168 (RD/BK) is sent to the audio unit when the ignition switch is turned to the START position. The audio unit then immediately mutes all speaker amplifier outputs and the subwoofer amplifier enable circuit output to eliminate the possibility of speaker pops during engine cranking.
The steering wheel audio control switch(es) consist of a specific resistor value for each button function creating a voltage divider. When a button is pressed a specific reference voltage is sent to the audio unit. The audio unit then uses this reference voltage to determine which control input function has been selected. Circuit 583 (YE) is the reference voltage circuit between the steering wheel audio controls and the audio unit. The ground circuit for the steering wheel audio controls is through the powertrain control module (PCM), circuit 848 (DG/OG).
The audio unit receives a vehicle speed signal from the powertrain control module (PCM) through circuit 679 (GY/BK). When the vehicle speed increases, the audio unit will receive this change in signal output from the PCM and increase the volume level. When the vehicle speed decreases, the audio unit will interpret this signal change and decrease the volume level.
When the key is turned to the ON or ACC position power is supplied to the digital versatile disc (DVD) unit and serves as a wake up signal. Once the DVD unit is powered up, a signal is sent to the audio unit through circuit 1068 so that communication between the audio unit and DVD unit can begin. When a video disc is inserted into the DVD unit and the PLAY button is pressed an image should be displayed on the screen.
When a movie is being played using the digital versatile disc (DVD) player, sound should be heard through all four speakers and the subwoofer.