Pinpoint Test M: The Audio Rear Control Unit (RCU) Module Does Not Respond To The Scan Tool

Communications Network

Pinpoint Test M: The Audio Rear Control Unit (RCU) Module Does Not Respond To The Scan Tool

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

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

Normal Operation

The audio Rear Control Unit (RCU) module 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

- Audio RCU (Rear Control Unit) module

PINPOINT TEST M : THE AUDIO RCU (Rear Control Unit) 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.

M1 CHECK THE AUDIO RCU (Rear Control Unit) MODULE VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Audio RCU (Rear Control Unit) Module C3077.

- Ignition ON.

- Measure the voltage between the audio RCU (Rear Control Unit) module C3077-16, circuit SBP03 (BU/RD), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to M2.

No
VERIFY the Smart Junction Box (SJB) fuse 3 (15A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. CLEAR the DTCs. REPEAT the network test with the scan tool.

M2 CHECK THE AUDIO RCU (Rear Control Unit) MODULE GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: Negative Battery Cable.

- Measure the resistance between the audio RCU (Rear Control Unit) module C3077-1, circuit GD114 (BK/BU), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to M3.

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

M3 CHECK THE MS-CAN (Medium Speed Controller Area Network) CIRCUITS BETWEEN THE AUDIO RCU (Rear Control Unit) MODULE AND THE DLC (Data Link Connector) FOR AN OPEN

- Measure the resistance between the audio RCU (Rear Control Unit) module C3077-8, 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 RCU (Rear Control Unit) module C3077-7, 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 M4.

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

M4 CHECK FOR CORRECT AUDIO RCU (Rear Control Unit) MODULE OPERATION

- Disconnect the audio RCU (Rear Control Unit) module connector.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect the audio RCU (Rear Control Unit) module 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 audio RCU (Rear Control Unit) module. 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.