| Diagnosis and Testing Refer to Wiring Diagrams Section 415-01, for schematic and connector information. Inspection and Verification - Verify the customer concern by operating the system.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Audio unit damage
- Cassette player jammed, not loading
- Compact disc (CD) player jammed, not loading
- Antenna/alignment
| - Fuse(s)
- Circuit(s)
- Electrical connector(s)
- Audio unit
- Speakers
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the cause is not visually evident, verify the symptom and refer to the Self-Diagnostic Mode.
Self-Diagnostic Mode - To enter the audio unit Self-Diagnostic Mode, switch the audio unit ON. Depress the preset buttons 5 and 6 together for 2 seconds.
- Release the preset buttons 5 and 6 and the audio unit will enter the Self-Diagnostic Mode.
- To exit the Self-Diagnostic Mode do not press any button on the audio unit for 10 seconds or press preset 6 for more than 1 second.
- If the Self-Diagnostic Mode cannot be accessed, use a diagnostic tool to diagnose the audio unit.
Self-Diagnostic Mode | Test | Syntax Displayed | Circuit Tested | Description | | 1. FM waveband check. | FM frequency received. | Antenna signal. | Tests signal from the antenna cable. | | 2. Traffic Announcement. | TP | Traffic announcement volume level. | Allows adjustment of the volume. | | 3. Test speaker circuit left hand front speaker. | 4CH LF for four channel system 2CH LF for two channel system. | Left hand front speaker circuit. | Test speaker circuit. | | 4. Test speaker circuit right hand front speaker. | 4CH RF for four channel system 2CH RF for two channel system. | Right hand front speaker circuit. | Test speaker circuit. | | 5. Test speaker circuit left hand rear speaker. | 4CH LR for four channel system 2CH LR for two channel system. | Left hand rear speaker circuit. | Test speaker circuit. | | 6. Test speaker circuit right hand rear speaker. | 4CH RR for four channel system 2CH RR for two channel system. | Right hand rear speaker circuit. | Test speaker circuit. | - If the concern remains after the Self-Diagnostic Mode, refer to the Symptom Chart.
Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | The audio unit is inoperative/does not operate correctly | * Fuse(s). * Circuit. * Audio unit. | * | | The display is blank - radio and cassette player operate | * Audio unit. | * INSTALL a new audio unit. | | Poor reception | * Antenna. * Antenna cable. * Audio unit. | * | | Poor quality/distorted sound from one or more speakers (not all speakers) | * Speaker(s). * Circuit(s). * Audio unit. | * | | No sound from all of the speakers | * Speaker(s). * Circuit(s). * Audio unit. | * | | The CD player does not operate correctly | * Audio unit. | * INSTALL a new audio unit. | | No sound from one or more of the speakers (not all speakers) | * Circuit(s). * Audio unit. | * | Pinpoint Tests | PINPOINT TEST A : THE AUDIO UNIT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | A1: CHECK FOR VOLTAGE TO AUDIO UNIT | | | 1 Disconnect Audio Unit C443. | | | 2 Ignition switch in position I. | | | 3 Measure the voltage between the audio unit C443 pin 1, circuit 29-MD15 (OG/BK), harness side and ground, and between the audio unit C443 pin 3, circuit 75-MD15 (YE/GN), harness side and ground. | | | Are the voltages greater than 10 volts? Yes No REPAIR circuit 29-MD15 (OG/BK) or circuit 75-MD15 (YE/GN). TEST the system for normal operation. | | A2: CHECK THE AUDIO UNIT GROUND CIRCUITS FOR OPEN | | | 1 Ignition switch in position 0. | | | 2 Measure the resistance between the audio unit C443 pin 6, circuit 91-MD15 (BK/GN), harness side and ground, and between the audio unit C443 pin 2, circuit 91-MD34 (BK/YE), harness side and ground. | | | Are the resistances less than 5 ohms? Yes INSTALL a new audio unit. TEST the system for normal operation. No REPAIR circuit 91-MD15 (BK/GN) or 91-MD34 (BK/YE). TEST the system for normal operation. | | PINPOINT TEST B : POOR RECEPTION | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | B1: CHECK THE ANTENNA CABLE SHIELD | | | 1 Ignition switch in position 0. | | | 2 Ignition switch in position 0. | | | 3 Disconnect Antenna Cable. | | | 4 Disconnect the antenna cable from the audio unit. | | | 5 Measure the resistance between the antenna cable ground connector (shield), and ground. | | | Is the resistance less than 1 ohm? Yes No CLEAN and TIGHTEN the audio unit case ground and the antenna base connection to the body. If the concern persists, INSTALL a new antenna cable. TEST the system for normal operation. | | B2: CHECK THE ANTENNA CENTER CONDUCTOR FOR OPEN | | | 1 Remove the antenna mast. | | | 2 Measure the resistance of the center conductor between the ends of the antenna cable. | | | Is the resistance less than 1 ohm? Yes No INSTALL a new antenna cable. TEST the system for normal operation. | | B3: CHECK ANTENNA CABLE FOR SHORT | | | 1 Measure the resistance between the antenna center conductor and the antenna ground (shield). | | | Is the resistance greater than 10,000 ohms? Yes CLEAN and TIGHTEN the ground connections at the base of the antenna, audio unit case and battery negative cable to the body. If concern the persists, INSTALL a new audio unit. TEST the system for normal operation. No INSTALL a new antenna cable. TEST the system for normal operation. | | PINPOINT TEST C : POOR QUALITY/DISTORTED SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS) | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | C1: CHECK THE SPEAKER RESISTANCE | | | 1 Disconnect Inoperative Speaker. | | | 2 Measure the resistance between the inoperative speaker pin 1 and pin 2, component side. | | | Is the resistance approximately 4.0 ohms? Yes No INSTALL a new speaker. TEST the system for normal operation. | | C2: CHECK SPEAKER INPUT FOR SHORT TO GROUND | | | 1 Disconnect Audio Unit C443. | | | 2 Measure the resistance between the inoperative speaker connector pin 1, harness side and ground. | | | Is the resistance greater than 10,000 ohms? Yes No REPAIR speaker input circuit. TEST the system for normal operation. | | C3: CHECK SPEAKER RETURN FOR SHORT TO GROUND | | | 1 Measure the resistance between the inoperative speaker connector pin 2, harness side and ground. | | | Is the resistance greater than 10,000 ohms? Yes INSTALL a new speaker. TEST the system for normal operation. If the concern persists, INSTALL a new audio unit. TEST the system for normal operation. No REPAIR speaker return circuit. TEST the system for normal operation. | | PINPOINT TEST D : NO SOUND FROM ALL OF THE SPEAKERS | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | D1: CHECK SPEAKER INPUT CIRCUIT FOR SHORT TO GROUND | | | 1 Ignition switch in position 0. | | | 2 Disconnect Audio Unit C442. | | | 3 Measure the resistance between the following audio unit connector pins and ground: - (Front left speaker) C442 pin 1, circuit 8-MD10 (WH/BK), harness side and ground.
- (Rear left speaker) C442 pin 3, circuit 8-MD11 (WH/GN), harness side and ground.
- (Front right speaker) C442 pin 5, circuit 8-MD17 (WH/RD), harness side and ground.
- (Rear right speaker) C442 pin 7, circuit 8-MD18 (WH), harness side and ground.
| | | Are the resistances greater than 10,000 ohms? Yes No REPAIR the circuit in question. TEST the system for normal operation. | | D2: CHECK SPEAKER RETURN CIRCUIT FOR SHORT TO GROUND | | | 1 Measure the resistance between the following audio unit connector pins and ground: - (Front left speaker) C442 pin 2, circuit 10-MD10 (GY/BK), harness side and ground.
- (Rear left speaker) C442 pin 4, circuit 10-MD11 (GY/WH), harness side and ground.
- (Front right speaker) C442 pin 6, circuit 10-MD17 (GY/RD), harness side and ground.
- (Rear right speaker) C442 pin 8, circuit 10-MD18 (GY), harness side and ground.
| | | Are the resistances greater than 10,000 ohms? Yes INSTALL a new audio unit. TEST the system for normal operation. No REPAIR the circuit in question. TEST the system for normal operation. | | PINPOINT TEST E : NO SOUND FROM ONE OR MORE OF THE SPEAKERS (NOT ALL SPEAKERS) | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | E1: CHECK THE SPEAKER RESISTANCE | | | 1 Disconnect Inoperative Speaker. | | | 2 Measure the resistance between the inoperative speaker pin 1 and pin 2, component side. | | | Is the resistance approximately 4.0 ohms? Yes No INSTALL a new speaker(s). TEST the system for normal operation. | | E2: CHECK SPEAKER CIRCUIT RESISTANCE - SPEAKER DISCONNECTED | | | 1 Disconnect Audio Unit C442. | | | 2 Measure the resistance between the audio unit C442 and the speaker connector pins for the inoperative speaker(s). - (Front left speaker) C442 pin 1, circuit 8-MD10 (WH/BK), harness side and C937 pin 2, circuit 8-MD28 (WH), harness side.
- (Front left speaker) C442 pin 2, circuit 10-MD10 (GY/BK), harness side and C937 pin 1, circuit 10-MD28 (GY), harness side.
- (Front right speaker) C442 pin 5, circuit 8-MD17 (WH/RD), harness side and C938 pin 2, circuit 8-MD28 (WH), harness side.
- (Front right speaker) C442 pin 6, circuit 10-MD17 (GY/RD), harness side and C938 pin 1, circuit 10-MD28 (BN), harness side.
- (Rear left speaker) C442 pin 3, circuit 8-MD11 (WH/GN), harness side and C939 pin 2, circuit 8-MD29 (WH/GN), harness side.
- (Rear left speaker) C442 pin 4, circuit 10-MD11 (GY/WH), harness side and C939 pin 1, circuit 10-MD11 (GY/WH), harness side.
- (Rear right speaker) C442 pin 7, circuit 8-MD18 (WH), harness side and C940 pin 2, circuit 8-MD29 (WH/GN), harness side.
- (Rear right speaker) C442 pin 8, circuit 10-MD18 (GY), harness side and C940 pin 1, circuit 10-MD29 (GY/WH), harness side.
| | | Is the resistance less than 5 ohms? Yes INSTALL a new speaker. TEST the system for normal operation. If concern persists, INSTALL a new audio unit. TEST the system for normal operation No REPAIR the circuit in question. TEST the system for normal operation. | |
