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

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Module Communications Network for schematic and connector information.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Audio System/Navigation for schematic and connector information.

Normal Operation 

The audio control module (ACM) communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the ACM. The ACM shares the MS-CAN with the instrument cluster (IC), the accessory protocol interface module (APIM), the smart junction box (SJB), the HVAC module (if equipped), the audio digital signal processing (DSP) module (if equipped), the satellite digital audio receiver system (SDARS) module (if equipped), the rear entertainment module (RETM) (if equipped), the driver seat module (DSM) (if equipped), the parking aid module (PAM) (if equipped), the liftgate/trunk module (LTM) and the dual climate control seat module (DCSM) (if equipped). Voltage for the ACM is provided by circuits CBP28 (GY/VT), CBP41 (BU) and SBP39 (WH/RD). Circuit GD114 (BK/BU) provides ground.

This pinpoint test is intended to diagnose the following:

• Fuse
• Wiring, terminals or connectors
• ACM

PINPOINT TEST K: THE AUDIO CONTROL MODULE (ACM) DOES NOT RESPOND TO THE SCAN TOOL 

1. K1 CHECK THE ACM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN 
   • Key in OFF position.
   • Disconnect: ACM C240a
   • Key in ON position.
   Fig 1: Checking Circuit For Voltage
   Courtesy of FORD MOTOR CO.
   • Measure the voltage between the ACM C240a-1, circuit SBP39 (WH/RD), harness side and ground; and between the ACM C240a-2, circuit CBP41 (BU), harness side and ground.
   • Are the voltages greater than 10 volts? 
   1. YES  : Go to  K2.
   2. NO  : VERIFY the smart junction box (SJB) fuse 39 (20A) or fuse 41 (15A) is OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
2. K2 CHECK THE ACM GROUND CIRCUIT FOR AN OPEN 
   • Key in OFF position.
   Fig 2: Checking Circuit For Open
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ACM C240a-13, circuit GD114 (BK/BU), harness side and ground.
   • Is the resistance less than 5 ohms? 
   1. YES  : Go to  K3.
   2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
3. K3 CHECK THE MS-CAN CIRCUITS BETWEEN THE ACM AND THE DLC FOR AN OPEN 
   • Disconnect: ACM C240b
   Fig 3: Checking MS-CAN Circuit For Open
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ACM C240b-15, circuit VDB06 (GY/OG), harness side and the DLC C251-3, circuit VDB06 (GY/OG), harness side.
   Fig 4: Checking MS-CAN Circuit For Open
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ACM C240b-16, circuit VDB07 (VT/OG), harness side and the DLC C251-11, circuit VDB07 (VT/OG), harness side.
   • Are the resistances less than 5 ohms? 
   1. YES  : Go to  K4.
   2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
4. K4 CHECK FOR CORRECT ACM OPERATION 
   • Disconnect all the ACM connectors.
   • Check for:
     • corrosion
     • damaged pins
     • pushed-out pins
   • Connect all the ACM connectors and make sure they seat correctly.
   • Operate the system and verify the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new ACM. REFER to INFORMATION AND ENTERTAINMENT SYSTEMS article. CLEAR the DTCs. REPEAT the network test with the scan tool. TEST the system for normal operation.
   2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.