Pinpoint Test E: The Audio Control Module (ACM) Illumination Is Inoperative

Instrument Cluster and Panel Illumination

Pinpoint Test E: The Audio Control Module (ACM) Illumination Is Inoperative

Refer to Wiring Diagrams Set 71, Cluster and Panel Illumination for schematic and connector information. Electrical Diagrams

Normal Operation

A variable Pulse Width Modulated (PWM) voltage is supplied to the Audio Control Module (ACM) from the instrument panel dimmer switch (part of the headlamp switch) when the side, main or parking lamps are on.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- ACM (Audio Control Module)

PINPOINT TEST E : THE ACM (Audio Control Module) ILLUMINATION IS INOPERATIVE

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

E1 CHECK THE ACM (Audio Control Module) ILLUMINATION CIRCUIT FOR VOLTAGE

- Ignition OFF.

- Disconnect: ACM (Audio Control Module) C240B.

- With the parking lamps on, rotate the instrument panel dimmer switch to the full illumination position.

- Measure the voltage between the ACM (Audio Control Module) C240B-14, circuit 29S-LK34 (OG/BK), harness side and ground.





Is the voltage greater than 10 volts?

Yes
GO to E2.

No
REPAIR circuit 29S-LK34 (OG/BK) for an open. TEST the system for normal operation.

E2 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). 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.