Pinpoint Test P: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) - Vehicles With Navigation
Information and Entertainment System
Pinpoint Test P: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) - Vehicles With Navigation
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information Electrical Diagrams.
Normal Operation
The Audio Front Control Module (ACM) directs audio signals to the audio amplifier in the form of an AC voltage. The ACM (Audio Front Control Module) provides internal circuit protection for shorts to ground or shorts to voltage. The tweeter speakers are integral to the front door speakers, and cannot be replaced separately.
A short to ground or short to voltage in the circuitry to the audio amplifier can cause multiple speakers to lose sound due to the built-in overload protection feature of the ACM (Audio Front Control Module). In this case this pinpoint test should be followed to isolate the damaged circuit.
To enable the audio amplifier, the ACM (Audio Front Control Module) sends voltage through the enable/clip circuit. The circuit acts as both an output (to enable the amplifier) and an input (to detect an amplifier overload condition). A variable resistor in the audio amplifier modifies the voltage signal from the ACM (Audio Front Control Module). In the event of an overload, the ACM (Audio Front Control Module) clips the audio output signal to the amplifier (heard as distortion), in order to prevent damage to the amplifier and speakers.
The enable/clip status is based on the following voltages, as detected by the ACM (Audio Front Control Module) :
- Less than 0.4 volt: amplifier disabled
- Between 3.8 and 6.7 volts: amplifier enabled
- Greater than 8.5 volts: amplifier clipped
An open in the enable/clip circuit causes the speakers to produce no sound, because the enable signal cannot reach the audio amplifier. A short to ground or short to voltage can cause severe distortion to be heard in the speakers. In either of these scenarios, the subwoofer should continue to operate correctly, as it utilizes a separate amplifier and enable/clip circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Speaker
- Audio amplifier
- ACM (Audio Front Control Module)
PINPOINT TEST P : POOR QUALITY/DISTORTED/NO SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS) - VEHICLES WITH NAVIGATION
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings.
P1 IDENTIFY THE INOPERATIVE SPEAKER
- Enter the following diagnostic mode on the scan tool: Speaker Walkaround Test.
- Carry out the speaker walkaround test.
Is the concern with the subwoofer speaker?
Yes
GO to Pinpoint Test D Pinpoint Test D: The Subwoofer Is Inoperative/Does Not Operate Correctly.
No
GO to P2.
P2 CHECK THE AUDIO SIGNALS TO THE SUSPECT SPEAKER
- Ignition OFF.
- Disconnect: Suspect Speaker.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the suspect speaker pin 1 and pin 2, harness side as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C523-1 VME07 (WH) C523-2 RME07 (WH/BN) RF door C612-1 VME10 (WH/VT) C612-2 RME10 (WH/OG) LR door C702-1 VME12 (BN/WH) C702-2 RME12 (BN/BU) RR door C802-1 VME12 (BN/WH) C802-2 RME12 (BN/BU)
Is a fluctuating AC voltage present?
Yes
INSTALL a new speaker for the suspect speaker. REFER to Speaker - Door . TEST the system for normal operation.
No
GO to P3.
P3 CHECK THE AUDIO SIGNALS TO THE AUDIO AMPLIFIER
- Ignition OFF.
- Disconnect: Audio Amplifier C3154A.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the audio amplifier pins for the suspect speaker, harness side as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C3154A-8 VME07 (WH) C3154A-4 RME07 (WH/BN) RF door C3154A-6 VME10 (WH/VT) C3154A-2 RME10 (WH/OG) LR door C3154A-7 VME09 (WH/GN) C3154A-3 RME09 (BN/YE) RR door C3154A-5 VME12 (BN/WH) C3154A-1 RME12 (BN/BU)
Is a fluctuating AC voltage present?
Yes
GO to P7.
No
GO to P4.
P4 CHECK THE AUDIO CIRCUITS TO THE AUDIO AMPLIFIER FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM (Audio Front Control Module) C240A.
- Ignition ON.
- Measure the voltage between the audio amplifier, harness side and ground as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C3154A-8 VME07 (WH) Ground C3154A-4 RME07 (WH/BN) Ground RF door C3154A-6 VME10 (WH/VT) Ground C3154A-2 RME10 (WH/OG) Ground LR door C3154A-7 VME09 (WH/GN) Ground C3154A-3 RME09 (BN/YE) Ground RR door C3154A-5 VME12 (BN/WH) Ground C3154A-1 RME12 (BN/BU) Ground
Is any voltage present?
Yes
REPAIR the circuit in question. CLEAR any DTCs present. REPEAT the self-test.
No
GO to P5.
P5 CHECK THE AUDIO CIRCUITS TO THE AUDIO AMPLIFIER FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the audio amplifier, harness side and ground as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C3154A-8 VME07 (WH) Ground C3154A-4 RME07 (WH/BN) Ground RF door C3154A-6 VME10 (WH/VT) Ground C3154A-2 RME10 (WH/OG) Ground LR door C3154A-7 VME09 (WH/GN) Ground C3154A-3 RME09 (BN/YE) Ground RR door C3154A-5 VME12 (BN/WH) Ground C3154A-1 RME12 (BN/BU) Ground
Are the resistances greater than 10,000 ohms?
Yes
GO to P6.
No
REPAIR the circuit in question. TEST the system for normal operation.
P6 CHECK THE AUDIO CIRCUITS TO THE AUDIO AMPLIFIER FOR AN OPEN
- Measure the resistance between the audio amplifier, harness side and the ACM (Audio Front Control Module), harness side as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead Circuit LF door C3154A-8 C240A-8 VME07 (WH) C3154A-4 C240A-21 RME07 (WH/BN) RF door C3154A-6 C240A-11 VME10 (WH/VT) C3154A-2 C240A-12 RME10 (WH/OG) LR door C3154A-7 C240A-9 VME09 (WH/GN) C3154A-3 C240A-22 RME09 (BN/YE) RR door C3154A-5 C240A-10 VME12 (BN/WH) C3154A-1 C240A-23 RME12 (BN/BU)
Are the resistances less than 5 ohms?
Yes
GO to P15.
No
REPAIR the circuit in question. TEST the system for normal operation.
P7 CHECK THE AUDIO AMPLIFIER VOLTAGE
- Ignition OFF.
- Disconnect: Audio Amplifier C3154B.
- Measure the voltage between the audio amplifier C3154B-1, circuit SBP39 (WH/RD), harness side and ground; and between the audio amplifier C3154B-8, circuit SBP39 (WH/RD), harness side and ground (if present).
Is the voltage greater than 10 volts?
Yes
GO to P8.
No
VERIFY the Smart Junction Box (SJB) fuse 39 (20A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams.
P8 CHECK THE AUDIO AMPLIFIER GROUND CIRCUIT FOR CONTINUITY
- Disconnect: Negative Battery Cable.
- Measure the resistance between the audio amplifier C3154B-7, circuit GD115 (BK/GY), harness side and ground; and between the audio amplifier C3154B-14, circuit GD115 (BK/GY), harness side and ground (if present).
Is the resistance less than 5 ohms?
Yes
GO to P9.
No
REPAIR the circuit. TEST the system for normal operation.
P9 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT VOLTAGE
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the audio amplifier C3154B-9, circuit CME27 (YE/VT), harness side and ground.
Is the voltage between 3.8 and 6.7 volts?
Yes
GO to P12.
No
GO to P10.
P10 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM (Audio Front Control Module) C240A.
- Ignition ON.
- Measure the voltage between the audio amplifier C3154B-9, circuit CME27 (YE/VT), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
GO to P11.
P11 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the audio amplifier C3154B-9, circuit CME27 (YE/VT), harness side and the ACM (Audio Front Control Module) C240A-7, circuit CME27 (YE/VT); and between the audio amplifier C3154B-9, circuit CME27 (YE/VT), harness side and ground.
Is the resistance less than 5 ohms between the audio amplifier and the ACM (Audio Front Control Module), and greater than 10,000 ohms between the audio amplifier and ground?
Yes
GO to P15.
No
REPAIR the circuit. TEST the system for normal operation.
P12 CHECK THE CIRCUITS TO THE SUSPECT SPEAKER FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between the suspect speaker, harness side and ground as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C523-1 VME07 (WH) Ground C523-2 RME07 (WH/BN) Ground RF door C612-1 VME10 (WH/VT) Ground C612-2 RME10 (WH/OG) Ground LR door C702-1 VME12 (BN/WH) Ground C702-2 RME12 (BN/BU) Ground RR door C802-1 VME12 (BN/WH) Ground C802-2 RME12 (BN/BU) Ground
Is any voltage present?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
GO to P13.
P13 CHECK THE CIRCUITS TO THE SUSPECT SPEAKER FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the suspect speaker, harness side and ground as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C523-1 VME07 (WH) Ground C523-2 RME07 (WH/BN) Ground RH front C612-1 VME10 (WH/VT) Ground C612-2 RME10 (WH/OG) Ground LH rear C702-1 VME12 (BN/WH) Ground C702-2 RME12 (BN/BU) Ground RH rear C802-1 VME12 (BN/WH) Ground C802-2 RME12 (BN/BU) Ground
Are the resistances greater than 10,000 ohms?
Yes
GO to P14.
No
REPAIR the circuit in question. TEST the system for normal operation.
P14 CHECK THE CIRCUITS TO THE SUSPECT SPEAKER FOR AN OPEN
- Measure the resistance between the audio amplifier, harness side and the suspect speaker, harness side as follows:
Suspect Speaker Positive Meter Lead Negative Meter Lead LF door C3154B-13 VME07 (WH) C523-1 VME07 (WH) C3154B-6 RME07 (WH/BN) C523-2 RME07 (WH/BN) RF door C3154B-11 VME10 (WH/VT) C612-1 VME10 (WH/VT) C3154B-4 RME10 (WH/OG) C612-2 RME10 (WH/OG) LR door C3154B-12 VME09 (WH/GN) C702-1 VME12 (BN/WH) C3154B-5 RME09 (BN/YE) C702-2 RME12 (BN/BU) RR door C3154B-10 VME12 (BN/WH) C802-1 VME12 (BN/WH) C3154B-3 RME12 (BN/BU) C802-2 RME12 (BN/BU)
Are the resistances less than 5 ohms?
Yes
INSTALL a new audio amplifier. REFER to Audio Amplifier . TEST the system for normal operation.
No
REPAIR the circuit in question. TEST the system for normal operation.
P15 CHECK FOR CORRECT ACM (Audio Front Control Module) OPERATION
- Connect: All Disconnected Connectors.
- Disconnect all the ACM (Audio Front Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM (Audio Front Control Module) connectors and make sure they seat correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes
INSTALL a new ACM (Audio Front Control Module). REFER to 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.