F 150 2WD V8-5.4L Flex Fuel (2008)
Information Bus: Initial Inspection and Diagnostic Overview
Inspection and Verification
INSPECTION AND VERIFICATION
1. Verify the customer concern.
2. Visually inspect for obvious signs of electrical damage.
VISUAL INSPECTION CHART
Electrical
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Central junction box (CJB) fuse(s):
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1 (10A) (instrument cluster [IC])
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3 (7.5A) (driver seat module [DSM])
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5 (7.5A) (heating ventilation air conditioning [HVAC] module)
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13 (10A) (HVAC module)
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14 (10A) (ABS module)
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15 (5A) (IC)
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18 (10A) (vehicle security module [VSM], parking aid module [PAM])
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19 (10A) (RCM)
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21 (15A) (IC)
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27 (5A) (IC)
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103 (20A) (ABS module)
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107 (30A) (VSM)
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109 (30A) (DSM)
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110 (20A) (no power to scan tool)
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112 (40A) (ABS)
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Data link connector (DLC)
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Wiring, terminals or connectors
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. NOTE: Make sure to use the latest scan tool software release.
If the cause is not visually evident, connect the scan tool to the DLC.
NOTE: The vehicle communication module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM.
If the scan tool does not communicate with the VCM:
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Check the VCM connection to the vehicle.
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Check the scan tool connection to the VCM.
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GO to Pinpoint Test M, to diagnose no power to the scan tool. See: Pinpoint Tests/Test M: No Power To The Scan Tool
5. NOTE: During the network test, the scan tool will first attempt to communicate with the PCM, after establishing communication with the PCM,
the scan tool will then attempt to communicate with all other modules on the vehicle.
Carry out the network test.
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If the network test passes, retrieve and record the continuous memory DTCs and proceed to Step 6.
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If the network test fails, GO to Symptom Chart to identify the module not communicating. See: Symptom Related Diagnostic Procedures
6. If the DTCs retrieved are related to the concern, go to DTC Charts. For all other DTCs, refer to Body Control Systems (Multifunction Electronic
Control Module). See: Diagnostic Trouble Code Descriptions/Module Communications Network
7. If no DTCs related to the concern are retrieved, GO to Symptom Chart. See: Symptom Related Diagnostic Procedures
Principles of Operation
PRINCIPLES OF OPERATION
Vehicle communication utilizes a high speed controller area network (HS-CAN), International Standards Organization (ISO) 9141 network and universal
asynchronous receiver/transmitter (UART) based protocol (UBP) network. Information is sent to and from individual control modules that each control
specific functions. All 3 networks are connected to the data link connector (DLC). The DLC can be found under the instrument panel between the
steering column and the audio control module (ACM).
The 3 module communication networks are:
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High speed (HS) CAN
