Pinpoint Test K: The Audio Control Module (ACM) Does Not Respond to the Scan Tool

Communications Network

Pinpoint Tests

Pinpoint Test K: The Audio Control Module (ACM) Does Not Respond To The Scan Tool

Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information. Diagrams By Number

Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number

Normal Operation

The Audio Control Module (ACM) communicate with the scan tool through the Medium Speed Controller Area Network (MS-CAN) circuits VDB06 (GY/OG) and VDB07 (VT/OG).

Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the ACM. Voltage for the ACM is provided by circuits CBP02 (GN) and SBP11 (BU/RD). Circuit GD114 (BK/BU) provides ground.

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- ACM



PINPOINT TEST K: THE ACM 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.

-------------------------------------------------
K1 CHECK THE ACM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN


- Ignition OFF.
- Disconnect: ACM C290a (Base Audio/Audiophile) or C240a (THX(R) Audio/Navigation).
- Ignition ON.
- Measure the voltage between the base ACM C290a-1 (base audio/audiophile) or ACM C240a-1 (THX(R) audio/navigation), circuit SBP11 (BU/RD), harness side and ground; and between C290a-2 (base audio/audiophile) or C240a-2 (THX(R) audio/navigation), circuit CBP02 (GN), harness side and ground.




- Are the voltages greater than 10 volts?

Yes
GO to K2.

No
VERIFY the Smart Junction Box (SJB) fuse 12 (7.5A) or fuse 18 (20A) is OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool. If not OK, REFER to the Wiring Diagrams to identify the possible cause of the circuit short.

-------------------------------------------------
K2 CHECK THE ACM GROUND CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the ACM C290a-13 (Base Audio/Audiophile) or the ACM C240a-13 (THX(R) audio/navigation), circuit GD114 (BK/BU), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to K3.

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

-------------------------------------------------
K3 CHECK THE MS-CAN CIRCUITS BETWEEN THE ACM AND THE DLC FOR AN OPEN


- Ignition OFF.
- Disconnect: ACM C290c (Base Audio/Audiophile) or C240c (THX(R) Audio/Navigation).
- Measure the resistance between the ACM C290c-15 (base audio/Audiophile) or the audio Digital Signal Processing (DSP) module C240c-15 (THX(R) audio/navigation), 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 ACM C290c-16 (base audio/Audiophile) or the audio DSP module ACM C240c-16 (THX(R) audio/navigation), 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 K4.

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

-------------------------------------------------
K4 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 Radio, Stereo and Compact Disc. 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. CLEAR the DTCs. REPEAT the network test with the scan tool.

-------------------------------------------------