Pinpoint Test W: DTC B1318 (Audio Control Module (ACM))

Information and Entertainment System

Pinpoint Tests

Pinpoint Test W: DTC B1318 (Audio Control Module (ACM))

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

Normal Operation
- DTC B1318 (Battery Voltage Low) - set by the Audio Control Module (ACM) as a continuous DTC if the ACM detects low battery voltage below 10 volts for greater than 10 seconds on circuit SBP39 (WH/RD). The ACM does not check the circuit for voltage with the key in START.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- High circuit resistance
- ACM



PINPOINT TEST W: DTC B1318 (ACM)

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.

-------------------------------------------------
W1 RECHECK THE ACM DTCs


- Clear the ACM DTCs.
- Ignition OFF.
- Ignition ON.
- Wait 10 seconds.
- Repeat the ACM self-test.
- Is DTC B1318 still present?

Yes
GO to W2.

No
The system is operating correctly at this time. The DTC may have been set due to a previous low battery voltage condition.

-------------------------------------------------
W2 CHECK FOR CHARGING SYSTEM DTCs IN THE PCM


- Retrieve the continuous memory DTCs from all modules.
- Is DTC P0620, P0622, P0625, P0626 or P065B set in the PCM?

Yes
REFER to Charging System.

No
GO to W3.

-------------------------------------------------
W3 CHECK THE BATTERY CONDITION AND STATE OF CHARGE


- Check the battery condition and verify that the battery is fully charged. Refer to Battery.
- Is the battery OK and fully charged?

Yes
GO to W4.

No
REFER to Battery.

-------------------------------------------------
W4 CHECK THE ACM VOLTAGE SUPPLY


- Ignition OFF.
- Measure and record the voltage at the battery.
- Disconnect: ACM C240a.
- Ignition ON.
- Measure the voltage between the ACM C240a-1, circuit SBP39 (WH/RD), harness side and ground.




- Is the voltage within 0.2 volt of the recorded battery voltage?

Yes
GO to W5.

No
REPAIR the circuit for high resistance. CLEAR the DTCs. REPEAT the self-test.

-------------------------------------------------
W5 CHECK THE ACM GROUND CIRCUIT


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the ACM C240a-13, circuit GD103 (BK/BU) harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to W6.

No
REPAIR the circuit for high resistance. CLEAR the DTCs. REPEAT the self-test.

-------------------------------------------------
W6 CHECK FOR CORRECT ACM OPERATION


- Connect: Negative Battery Cable.
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM connectors and make sure they seat correctly.
- Is the concern still present?

Yes
INSTALL a new ACM. REFER to Audio Control Module (ACM) Audio Control Module (ACM). 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.

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