Pinpoint Test L: The Audio Digital Signal Processing (DSP) Module Does Not Respond to the Scan Tool

Communications Network

Pinpoint Tests

Pinpoint Test L: The Audio Digital Signal Processing (DSP) Module Does Not Respond To The Scan Tool

Normal Operation

The audio Digital Signal Processing (DSP) module communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the DSP module. Voltage for the audio DSP module amplifier is provided by circuits SBB20 (GN/RD) and SBB21 (GY/RD). Circuit GD148 (BK/YE) provides ground.

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- Audio DSP module



PINPOINT TEST L: PINPOINT TEST L: THE AUDIO DSP MODULE DOES NOT RESPOND TO THE SCAN TOOL

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. Refer to Battery.

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L1 CHECK THE AUDIO DSP MODULE VOLTAGE SUPPLY CIRCUITS FOR AN OPEN


- Ignition OFF.
- Disconnect: Audio DSP Module C4326b.
- Ignition ON.
- Measure the voltage between the audio DSP module, harness side and ground as follows:





- Are the voltages greater than 10 volts?

Yes
GO to L2.

No
VERIFY the Battery Junction Box (BJB) fuse 20 (20A) or fuse 21 (20A) is OK. If OK, REPAIR the circuit in question. CONNECT the PCM. CLEAR the DTCs. REPEAT the network test with the scan tool.

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L2 CHECK THE AUDIO DSP MODULE GROUND CIRCUITS FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the audio DSP module amplifier, harness side and ground as follows:





- Are the resistances less than 5 ohms?

Yes
GO to L3.

No
REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.

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L3 CHECK THE MS-CAN CIRCUITS BETWEEN THE AUDIO DSP MODULE AND THE DLC FOR AN OPEN


- Ignition OFF.
- Disconnect: Audio DSP Module C4326c.
- Measure the resistance between the audio DSP module C4326c-11, circuit VDB06 (GY/OG), harness side and the Data Link Connector (DLC) C251-3, circuit VDB06 (GY/OG), harness side.




- Measure the resistance between the audio DSP module C4326c-1, circuit VDB07 (VT/OG), harness side and the DLC C251-11, circuit VDB07 (VT/OG), harness side.




- Are the resistances less than 5 ohms?

Yes
CONNECT the negative battery cable. GO to L4.

No
REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.

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L4 CHECK FOR CORRECT AUDIO DSP MODULE OPERATION


- Disconnect all the audio DSP module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the audio DSP module 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 audio DSP module. REFER to Radio, Stereo and Compact Disc. CLEAR the DTCs. REPEAT the network test with the scan tool.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.

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