Diagnostic Routine C

Diagnostic Routine C

Diagnostic Overview

No Sound From All Speakers

Refer to Wiring Diagram Set 130 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

When the key is in START, the ACM (Audio Control Module) receives voltage on the START signal circuit. The ACM (Audio Control Module) then mutes the speaker output to prevent voltage spikes from producing a popping noise through the speakers. However, a short to voltage on this circuit causes the ACM (Audio Control Module) output to be continuously muted.

If a speaker circuit fault DTC (Diagnostic Trouble Code) is set in the ACM (Audio Control Module), the cause of the concern is a short to ground or short to voltage in an individual speaker circuit, which has caused the ACM (Audio Control Module) overload protection to activate. If a speaker circuit fault DTC (Diagnostic Trouble Code) is present, REFER to DTC Chart: Audio Control Module (ACM) - Premium DTC Chart: Audio Control Module (ACM) - Premium.

Pinpoint Test

1. CHECK THE START SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE

1. Ignition OFF.

2. Disconnect: ACM (Audio Control Module) C240A.

3. Ignition ON.

4. Measure:





Is voltage present?








2. CHECK FOR SPEAKER DTCs (Diagnostic Trouble Codes)

1. Ignition ON.

2. Using a scan tool, perform the ACM (Audio Control Module) self-test.

Are any DTCs (Diagnostic Trouble Codes) present?








3. CHECK FOR CORRECT ACM (Audio Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect all ACM (Audio Control Module) connectors.

3. Repair:

- corrosion (install new connectors or terminals - clean module pins)
- damaged or bent pins - install new terminals pins
- pushed-out pins - install new pins as necessary

4. Reconnect the ACM (Audio Control Module) connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?