Diagnostic Methods

Ford On-Demand Diagnostic Trouble Codes

Ford Motor Company modules have a unique feature that performs a special diagnostic program at the request of the technician (using a diagnostic scan tool). This "On-demand" diagnostic program can exercise system outputs not normally running when the car is parked and record observed faults. These diagnostic codes are communicated to the scan tool, but are not recorded in module memory. An on-demand test is an effective tool for evaluating real input and output conditions during module activity – activity that might not normally be occurring during service bay conditions. For example, an air suspension module on-demand test can run the compressor, vent the system, and observe the report from the height sensor even when the car is already at correct trim height and not requiring height adjustment.

Network Communication Diagnostic Trouble Codes

Network DTCs (U-prefix codes) are often a result of intermittent concerns such as damaged wiring or low battery voltage occurrences. Additionally, vehicle repair procedures (such as module reprogramming or diagnostics with modules disconnected) often set network DTCs. Replacing a module to resolve a network DTC is unlikely to resolve the concern. To prevent recurrence of intermittent network concerns, inspect all network wiring, especially in-line and module connectors. Test the vehicle battery to make sure the vehicle voltage will be stable.

Recommended practice: Clear the DTC and retest. If the DTC repeats, test the vehicle communication network.

DTC Nomenclature (SAE J2012 and ISO 14229)

Many modules use 5-character DTCs followed by a 2-character failure-type code. The failure-type (sometimes called "fault byte") codes provide information about specific fault conditions such as opens or shorts to ground. Continuous memory DTCs have an additional 2-character DTC status code suffix to assist in determining DTC history.

Integrated Diagnostic System Scan Tool Usage

If The Integrated Diagnostic System Scan Tool Does Not Communicate With The Vehicle Communication Module

1. Check the Vehicle Communication Module connection and power from the DLC.

2. Check the communication between the scan tool and the Vehicle Communication Module.

3. Follow scan tool instructions to retry.

If The Integrated Diagnostic System Scan Tool Does Not Communicate With The Vehicle

The IDS scan tool first attempts to communicate with the PCM. After establishing communication with the PCM, the scan tool then attempts to communicate with all other modules on the vehicle.

1. Verify the scan tool operation with a known good vehicle.

2. Verify the ignition is ON.

3. If an IDS session cannot be established with the vehicle, ( IDS may state "No communication can be established with the PCM"): Choose "NO" when the scan tool prompts to retry communication. Enter a PCM engineering part number, tear tag, or calibration number to identify the vehicle and start a session. These identifying numbers may be found:

The PCM engineering part number and the 4-character tear tag are printed on the PCM label. (PTS website users only) The PCM engineering part number can be determined from OASIS using the VIN. Choose “HVBoM” from the OASIS tab menu and search Powertrain engine modules for the PCM engineering part number (If the first character is a "P" in the part number, enter only the characters following the "P" into IDS).

Establish a session based on the PCM information (above).

4. Using the tool box menu, run the network test. Determine if all modules on the network are unresponsive or if only the PCM does not communicate. Recommended practice: Refer to section 418-00 Module Communications Network, Diagnosis and Testing, to diagnose the network outage or no response from the PCM.