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

Communications Network

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


Normal Operation

The Audio Control Module (ACM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- ACM (Audio Control Module)

PINPOINT TEST K : THE ACM (Audio Control 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.

K1 CHECK THE ACM (Audio Control Module) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: ACM (Audio Control Module) C240A.

- Ignition ON.

- Measure the voltage between:
- the ACM (Audio Control Module) C240A-1, circuit SBP29 (GY/RD), harness side and ground.
on vehicles equipped with single CD/base audio, the ACM (Audio Control Module) C240A-2, circuit CBP38 (GY/BU), harness side and ground.






Are the voltages greater than 10 volts?

Yes
GO to K2.

No
VERIFY the Body Control Module (BCM) fuse 29 (20A) or fuse 38 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. On vehicles equipped with single CD/base audio, REFER to Windows and Glass to diagnose the delayed accessory is inoperative.CLEAR the DTCs. REPEAT the network test with the scan tool. [1][2]Diagrams By Number

K2 CHECK THE ACM (Audio Control Module) GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Negative Battery Cable.

- Measure the resistance between the ACM (Audio Control Module) C240A-13, circuit GD114 (BK/BU or BK), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to K3.

No
REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.

K3 CHECK THE MS-CAN (Medium Speed Controller Area Network) CIRCUITS BETWEEN THE ACM (Audio Control Module) AND THE DLC (Data Link Connector) FOR AN OPEN

- Disconnect: ACM (Audio Control Module) C240C.

- Measure the resistance between the ACM (Audio Control Module) C240C-15, 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 (Audio Control Module) C240C-16, circuit VDB07 (VT/OG), harness side and the DLC (Data Link Connector) 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. CLEAR the DTCs. REPEAT the network test with the scan tool.

K4 CHECK FOR CORRECT ACM (Audio Control Module) OPERATION

- Disconnect all the ACM (Audio Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the ACM (Audio Control 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 ACM (Audio Control Module). 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.