Pinpoint Test U: Poor Quality/Distorted/No Sound - SYNC System
Information and Entertainment System
Pinpoint Tests
Pinpoint Test U: Poor Quality/Distorted/No Sound - SYNC System
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 132, Video System for schematic and connector information. Diagrams By Number
Normal Operation
The Accessory Protocol Interface Module (APIM) transmits left and right channel analog audio signals. The signals include inputs from the Universal Serial Bus (USB) port, the audio input jack, and a Bluetooth media device.
If the vehicle is equipped with the family entertainment system, these audio signals are sent to the Rear Entertainment Module (RETM), then to the Audio Control Module (ACM). In vehicles without the family entertainment system, the audio signals are sent directly to the ACM.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- APIM
- RETM (if equipped)
- ACM
PINPOINT TEST U: POOR QUALITY/DISTORTED SOUND - SYNC SYSTEM
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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U1 VERIFY THE OPERATION OF THE SYNC SYSTEM AUDIO SOURCES
- Connect: Multi-Media Interface Tester.
- Using the Multi-Media Interface Tester, test the audio output for the audio input jack, USB port, and Bluetooth connection.
- Is there poor quality/distorted sound from each SYNC audio source?
Yes
If the vehicle is equipped with the family entertainment system, GO to U2.
Otherwise, GO to U3.
No
If the concern is only with one of the audio sources, GO to Symptom Chart - SYNC System to diagnose the observed symptom. Symptom Chart - SYNC System
If all audio sources operate correctly, the concern is with the customer device.
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U2 CHECK THE OPERATION OF THE FAMILY ENTERTAINMENT SYSTEM AUDIO
- NOTE: Make sure a known good DVD is inserted in the RETM before carrying out this step.
- Operate the audio system in single-play DVD mode.
- Observe the audio output.
- Is there poor quality/distorted sound while in DVD mode?
Yes
GO to Pinpoint Test G. Pinpoint Test G: The Family Entertainment System Is Inoperative/Does Not Operate Correctly
No
GO to U3.
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U3 CHECK THE AUDIO CIRCUITS FROM THE APIM FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C290b (Vehicles Without A Family Entertainment System).
- Disconnect: RETM C9029 (Vehicles With A Family Entertainment System).
- Disconnect: APIM C3342.
- Measure the voltage between the APIM, harness side and ground as follows:
- Is any voltage present?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
GO to U4.
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U4 CHECK THE AUDIO CIRCUITS FROM THE APIM FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the APIM, harness side, and the ACM (or RETM if equipped with the family entertainment system), harness side; and between the APIM, harness side and ground as follows:
- Is the resistance less than 5 ohms between the APIM and the ACM (or RETM), and greater than 10,000 ohms between the APIM and ground?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
GO to U5.
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U5 CHECK FOR CORRECT APIM OPERATION
- Connect: All Disconnected Connectors.
- Disconnect the APIM connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the APIM connector and make sure it seats correctly.
- Wait 2 minutes for the APIM to re-initialize.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new APIM. REFER to Accessory Protocol Interface Module (APIM) Accessory Protocol Interface Module (APIM). TEST the system for normal operation. If the concern is still present and the vehicle is equipped with the family entertainment system, GO to U6. If the concern is still present and the vehicle is not equipped with the family entertainment system, GO to U7.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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U6 CHECK FOR CORRECT RETM OPERATION
- Disconnect the RETM connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the RETM connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new RETM. REFER to Rear Entertainment Module (RETM) Service and Repair. TEST the system for normal operation. If the concern is still present, GO to U7.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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U7 CHECK FOR CORRECT ACM OPERATION
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new ACM. REFER to Audio Control Module (ACM) Audio Control Module (ACM). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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