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

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. E1 CHECK THE ACM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: ACM C290d
    • Key in ON position.
      • Fig 1: Checking Circuits 797 (LG/VT) And 687 (GY/YE) For Voltage
      GF0016188Courtesy of FORD MOTOR CO.
    • Measure the voltage between the ACM C290d-1, circuit 729 (RD/WH), harness side and ground; and between the ACM C290d-2, circuit 687 (GY/YE), harness side and ground.
    • Are the voltages greater than 10 volts? 
    1. YES  : Go to  E2.
    2. NO  : VERIFY the bussed electrical center (BEC) fuse 56 (20A) or the smart junction box (SJB) fuse 6 (5A) is OK. If OK, REPAIR the circuit in question. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS to IDENTIFY the possible causes of the short circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. E2 CHECK THE ACM GROUND CIRCUIT FOR AN OPEN 
    • Key in OFF position.
    • Measure the resistance between the ACM C290d-13, circuit 1204 (BK/OG), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  E3.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. E3 CHECK THE MS-CAN CIRCUITS BETWEEN THE ACM AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN 
    • Disconnect: ACM C290a
      • Fig 2: Measuring Resistance Between Audio Unit C290A-15 And DLC C251-3
      GF0016189Courtesy of FORD MOTOR CO.
    • Measure the resistance between the ACM C290a-15, circuit 1847 (WH/OG), harness side and the DLC C251-3, circuit 1847 (WH/OG), harness side.
      • Fig 3: Measuring Resistance Between Audio Unit C290A-16 And DLC C251-11
      GF0016190Courtesy of FORD MOTOR CO.
    • Measure the resistance between the ACM C290a-16, circuit 1848 (PK/OG), harness side and the DLC C251-11, circuit 1848 (PK/OG), harness side.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  E4.
    2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. E4 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.
    • Repeat the network test.
    • Does the ACM still fail to communicate with the scan tool? 
    1. YES  : INSTALL a new ACM. REFER to INFORMATION AND ENTERTAINMENT SYSTEMS . 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.
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