| Diagnosis and Testing Special Tool(s) | | 73III Automotive Meter 105-R0057 or equivalent | | | Flex Probe Kit 105-R025C or equivalent | Principles of Operation A fluctuating AC voltage audio signal is sent to the speakers directly from the audio unit to reproduce sound. The audio unit has a self-diagnostic mode that can be entered by pressing preset buttons 3 and 6 simultaneously. Inspection and Verification - Verify the customer concern.
- Visually inspect the following for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Audio unit
- Antenna or antenna cable
- Speaker mounting/speaker cones
- Radio ignition interference capacitor, radio frequency interference suppression bond, or radio receiver hood bonding strap
| - Smart junction box (SJB) fuse(s):
- Circuitry
- Audio unit
| - If the concern is not visually evident, proceed to the Speaker Walk-Around Test and the Audio Unit Self-Diagnostic Mode.
Speaker Walk-Around Test NOTE:To enter the speaker walk-around test or audio unit self-diagnostic mode, the audio unit must be turned on and in the radio tuner mode (AM/FM). - To enter the speaker walk-around test, simultaneously press the audio unit preset buttons 3 and 6.
- The speaker walk-around test stops at each speaker and applies sound to each speaker for about 1-2 seconds. Each speaker is tested and displayed on the audio unit in the following sequence: RF, LF, LR, and RR.
- To exit the speaker walk-around test, turn the ignition switch off, turn the audio unit off, or press preset button 1 for diagnostics (DIA).
Audio Unit Self-Diagnostic Mode NOTE:To enter the speaker walk-around test or audio unit self-diagnostic mode, the audio unit must be turned on and in radio tuner mode (AM/FM). - To enter the following tests, press the desired preset button while in the speaker walk-around test or while in the audio unit self-diagnostic mode.
- To exit the audio unit self-diagnostic mode, turn the ignition switch or the audio unit off.
- If the concern remains and the fault is not detected, GO to Symptom Chart to continue diagnostics.
- The self-diagnostic mode has 6 manual tests available:
- Preset button 1 = ENTER DIAGNOSTICS. This test enters diagnostics from the speaker walk-around test. Metrics are available with SEL and ON buttons indicating time played in AM/FM, media, number of buttons pressed, etc.
- Preset button 2 = EEPROM BLOCK STATUS. This test shows the validity of memory to calibrate the clock, and seek sensitivity.
- Preset button 3 = EXIT DIAGNOSTICS.
- Preset button 4 = Software configuration level. This test queries each radio system controller for its software configuration level.
- Preset button 5 = DISPLAY TEST. This test lights all the display segments for five seconds and then turns all segments off.
- Preset button 6 = RAM CONTENTS READOUT. To enter these tests, press preset button 1 while in the speaker walk-around test, then the desired preset button.
- To exit the self-diagnostic mode, turn the audio unit or the ignition switch off.
- If the concern remains and the fault is not detected, GO to Symptom Chart to continue diagnostics.
Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | The audio unit display is blank, but the audio unit operates | * Audio unit | * REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | | During CD mode, the audio unit display shows: NO CD | * No CD found | * INSERT a known good CD. - If the concern is still present, REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. - Otherwise, NOTIFY the customer of the faulty CD. | | One or more audio control buttons (such as volume, seek, tune, and scan) is inoperative in either radio, tape, or all modes, but the audio unit display functions correctly | * Audio unit | * REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | | When the headlamp switch is in the PARK or ON position, there is no front audio unit backlighting, but all other backlighting functions are normal | * Circuitry * Audio unit | * | | The audio unit is inoperative/does not operate correctly | * Fuse * Circuitry * Audio unit | * | | Poor reception | * Antenna * Antenna cable(s) * Antenna connections * Noise suppression equipment * Radio frequency interference suppression equipment * Audio unit * Generator * Ignition system | * | | Continuous SEEK/SCAN in AM/FM | * Antenna * Antenna cable(s) * Antenna connections * Noise suppression equipment * Radio frequency interference suppression equipment * Audio unit | * | | No sound from all speakers | * Fuse * Circuitry * Audio unit | * | | Poor quality/distorted/no sound from one or more speakers (not all speakers) | * Circuitry * Speaker(s) * Audio unit | * | | Poor quality/distorted sound from all speakers | * Audio unit | * If the condition only occurs when the vehicle is running, GO to Pinpoint Test b. Otherwise, REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | | Loud popping sound when cycling the ignition | * Circuitry * Audio unit * Smart junction box (SJB) | * REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | Pinpoint Test Pinpoint Test A: The Audio Unit is Inoperative/Does Not Operate Correctly Refer to Wiring Diagrams Cell 130, for schematic and connector information. Normal Operation The audio unit receives power on circuit 137 (YE/BK) (hot in RUN/ACC) and circuit 956 (OG/LG) (hot at all times). The audio unit is grounded on circuit 694 (BK/LG). With the ignition switch in the RUN/ACC position, all of the features are operational. Possible Causes - Fuse
- Circuit 137 (YE/BK) open
- Circuit 956 (OG/LG) open
- Circuit 694 (BK/LG) open
- Audio unit
| PINPOINT TEST A : THE AUDIO UNIT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY | CAUTION:Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | A1: CHECK THE OPERATION OF THE AUDIO UNIT | | | 1 Ignition switch in position II. | | | 2 Turn on the audio unit. | | | Is the audio unit display illuminated? Yes No | | A2: CHECK FOR SOUND COMING FROM THE AUDIO SPEAKERS | | | 1 Verify that sound is coming from the audio speakers. | | | Is there sound coming from the audio speakers? Yes No If one or more (but not all) speakers have no sound, GO to Pinpoint Test c.If all the speakers have no sound, REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | | A3: CHECK THE AUDIO UNIT CONTROLS AND FEATURES | | | 1 Refer to the Owner's Literature for audio system controls. | | | 2 Verify that the controls and features operate correctly. | | | Do the controls and features operate correctly? Yes The system is operating normally at this time. No If all of the controls and features are inoperative, GO to A4. .If some of the controls and features are only partially inoperative, REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | | A4: CHECK THE VOLTAGE AT THE AUDIO UNIT | | | 1 Ignition switch in position 0. | | | 2 Disconnect Audio Unit . | | | 3 Ignition switch in position II. | | | 4 Measure the voltage between the audio unit C290a-1, circuit 956 (OG/LG), harness side and ground; and between the audio unit C290a-3, circuit 137 (YE/BK), harness side and ground. | | | Are the voltages greater than 10 volts? Yes No VERIFY the smart junction box (SJB) fuse 7 (10A) or fuse 12 (5A) is OK. If OK, REPAIR the circuit in question. TEST the system for normal operation. | | A5: CHECK THE AUDIO UNIT GROUND CIRCUITS FOR AN OPEN | | | 1 Ignition switch in position 0. | | | 2 Measure the resistance between the audio unit C290a-6, circuit 694 (BK/LG), harness side and ground. | | | Is the resistance less than 5 ohms? Yes SEND the audio unit to an authorized audio system repair facility. TEST the system for normal operation after the repair. No REPAIR the circuit. TEST the system for normal operation. | Pinpoint Test B: Poor Reception Normal Operation 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 engine ignition and electrical systems interference transmitted through the speakers. 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 the torque specifications. Possible Causes - Antenna
- Antenna cable(s)
- Antenna connections
- Noise suppression equipment
- Radio frequency interference suppression equipment
- Generator
- Ignition system
- Audio unit
| PINPOINT TEST B : POOR RECEPTION | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | B1: CHECK THE RECEPTION WITH THE VEHICLE RUNNING | | | 1 Ignition switch in position II. | | | 2 Operate the audio unit. | | | 3 Start the vehicle. | | | 4 Operate the audio unit. | | | Does the poor reception only occur while the vehicle is running? Yes No | | B2: CHECK THE SUPPRESSION EQUIPMENT/MOUNTING AND CONNECTING CIRCUITS | | | 1 Check all the necessary suppression equipment and the radio frequency interference suppression bond. | | | 2 Check the radio receiver hood bonding strap for integrity, cleanliness and metal-to-metal contact. | | | NOTE:The capacitor mounting points are used to complete the electrical circuit and must be mounted securely to clean surfaces. 3 Check the mounting and connecting circuits of the radio ignition interference capacitor for integrity, cleanliness and metal-to-metal contact. | | | Are the connections clean, secure, and in metal-to-metal contact? Yes No CLEAN, SECURE and INSTALL new suppression equipment as necessary. TEST the system for normal operation. | | B3: CHECK THE RADIO IGNITION INTERFERENCE CAPACITOR | | | 1 Check the operation of the radio ignition interference capacitor by installing a known good component. | | | 2 Start the vehicle. | | | 3 Turn the audio unit on and check the sound from the speakers. | | | Is the reception OK? Yes INSTALL a new radio ignition interference capacitor. TEST the system for normal operation. No | | B4: CHECK THE GENERATOR | | | 1 Ignition switch in position 0. | | | 2 Check the generator by disconnecting the wiring harness from the voltage regulator. | | | 3 Start the vehicle. | | | 4 Turn the audio unit on and check the radio reception. | | | Is the reception OK? Yes No REPAIR the ignition system as necessary. TEST the system for normal operation. | | B5: CHECK THE ANTENNA GROUND | | | 1 Measure the resistance between the antenna base and the battery ground cable. | | | Is the resistance less than 5 ohms? Yes No | | B6: CHECK THE ANTENNA CONNECTIONS | | | 1 Ignition switch in position 0. | | | 2 Check the antenna connections. | | | 3 Make sure the antenna is securely mounted to the vehicle body at ground points. | | | Are the connections clean, secure, and in metal-to-metal contact? Yes No CLEAN and SECURE the antenna connections as needed. TEST the system for normal operation. | | B7: SUBSTITUTE THE ANTENNA | | | 1 Substitute a known good antenna. Ground the antenna base to an unpainted metal surface on the vehicle. | | | 2 Ignition switch in position II. | | | 3 Operate the audio unit in radio tuner mode. | | | Is the reception OK? Yes INSTALL a new antenna. REFER to Section 415-02 Antenna. TEST the system for normal operation. No | | B8: SUBSTITUTE THE ANTENNA LEAD-IN CABLE | | | 1 Ignition switch in position 0. | | | 2 Substitute a known good antenna lead-in cable. | | | 3 Ignition switch in position II. | | | 4 Operate the audio unit in radio tuner mode. | | | Is the reception OK? Yes INSTALL a new antenna lead-in cable. REFER to Section 415-02 Antenna. TEST the system for normal operation. No | | B9: SUBSTITUTE THE AUDIO UNIT | | | 1 Ignition switch in position 0. | | | 2 Substitute a known good audio unit. | | | 3 Ignition switch in position II. | | | 4 Operate the audio unit in radio tuner mode. | | | Is the reception OK? Yes SEND the original audio unit to an authorized audio system repair facility. TEST the system for normal operation after the repair. No | | B10: REPOSITION COMPONENTS | | | 1 Ignition switch in position 0. | | | 2 Determine if the noise can be eliminated by repositioning the antenna extension cable, audio speaker circuits, or audio unit power feed circuits away from other circuits and/or brackets. | | | 3 Start the vehicle. | | | 4 Operate the audio unit in radio tuner mode. | | | Is the reception OK? Yes Permanently REPOSITION the components as needed. TEST the system for normal operation. No GROUND various parts of the vehicle to the frame using a jumper cable. (For example: engine, fenders, quarter panels, stone deflectors, body sheet metal.) When the noise is eliminated, PROVIDE a permanent ground where necessary. TEST the system for normal operation. | Pinpoint Test C: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) Refer to Wiring Diagrams Cell 130, for schematic and connector information. Normal Operation The audio unit directs the audio signals to the speakers through separate positive and negative circuits for each of the 4 audio channels: LH front, RH front, LH rear, and RH rear. The audio unit provides internal circuit protection for shorts to ground, shorts to voltage, or shorts between any output circuits. Possible Cause - Circuit 800 (GY/LB) open, short to ground
- Circuit 801 (TN/YE) open, short to ground
- Circuit 802 (OG/RD) open, short to ground
- Circuit 803 (BN/PK) open, short to ground
- Circuit 804 (OG/LG) open, short to ground
- Circuit 805 (WH/LG) open, short to ground
- Circuit 811 (DG/OG) open, short to ground
- Circuit 813 (LB/WH) open, short to ground
- Speaker(s)
- Audio unit
| PINPOINT TEST C : POOR QUALITY/DISTORTED/NO SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS) | CAUTION:Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | C1: CHECK FOR AN OPEN OR SHORT TO GROUND IN THE SUSPECT SPEAKER(S) AND CIRCUITS | | | 1 Ignition switch in position 0. | | | 2 Disconnect Audio Unit . | | | NOTE:If all the speakers have poor quality/distorted/no sound, only a measurement between each circuit and ground needs to be taken. 3 Measure the resistance between each pair of circuits at the audio unit; and between each pair of circuits and ground as follows: | Speaker | Connector- Pin | Circuit | Connector- Pin | Circuit | | RH front | C290b-5 | 805 (WH/LG) | C290b-6 | 811 (DG/OG) | | LH front | C290b-1 | 804 (OG/LG) | C290b-2 | 813 (LB/WH) | | RH rear | C290b-7 | 802 (OG/RD) | C290b-8 | 803 (BN/PK) | | LH rear | C290b-3 | 801 (TN/YE) | C290b-4 | 800 (GY/LB) | | | | Are the resistances between each pair of pins between 3.5 and 4.5 ohms, and greater than 10,000 ohms between each circuit and ground? Yes No | | C2: CHECK THE RESISTANCE IN THE CIRCUITS TO THE SUSPECT SPEAKER(S) | | | 1 Disconnect Suspect Speaker. | | | 2 Measure the resistance between the audio unit, harness side and the suspect speaker, harness side; and between the audio unit, harness side and ground as follows: | Speaker | Audio Unit Connector- Pin | Speaker Connector- Pin | Circuit | | RH front | C290b-5 | C612-1 | 805 (WH/LG) | | RH front | C290b-6 | C612-2 | 811 (DG/OG) | | LH front | C290b-1 | C523-1 | 804 (OG/LG) | | LH front | C290b-2 | C523-2 | 813 (LB/WH) | | RH rear | C290b-7 | C802-1 | 802 (OG/RD) | | RH rear | C290b-8 | C802-2 | 803 (BN/PK) | | LH rear | C290b-3 | C702-1 | 801 (TN/YE) | | LH rear | C290b-4 | C702-2 | 800 (GY/LB) | | | | Are the resistances less than 5 ohms between the audio unit and the speaker(s), and greater than 10,000 ohms between the audio unit and ground? Yes INSTALL a new door speaker. REFER to Section 415-03 Speakers. TEST the system for normal operation. No REPAIR the circuit. TEST the system for normal operation. | | C3: CHECK THE AUDIO SIGNAL OUTPUT TO THE SPEAKER WITH POOR QUALITY/DISTORTED/NO SOUND | | | 1 Connect Audio Unit . | | | 2 Disconnect Suspect Speaker. | | | 3 Ignition switch in position II. | | | 4 Operate the audio unit in radio tuner mode. | | | 5 Measure the AC voltage between pin 1 and pin 2 of the suspect speaker, harness side. | | | Is a fluctuating AC voltage present? Yes INSTALL a new door speaker. REFER to Section 415-03 Speakers. TEST the system for normal operation. No REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to Section 415-01 Audio Unit. TEST the system for normal operation after the repair. | |
