Engine Controls - Diagnostic Methods (Except Diesel & Hybrid): Overview Ford Econoline E350 Super Duty

Overview

Diagnostic Methods provides information on routine diagnostic tasks.

When following powertrain diagnostics on on-board diagnostics (OBD) vehicles, the system may be checked by an off-board tester referred to as a diagnostic tool. This article contains information for carrying out diagnostics with a diagnostic tool. A diagnostic tool has certain generic capabilities that are standard across the automotive industry in the United States. All functions are selected from a menu. Refer to the instruction manual provided by the tool manufacturer.

Description

The parameter identification (PID) mode allows access to PCM information. This includes analog and digital signal inputs and outputs along with calculated values and the system status. There are two types of PID lists available. The first is the generic (J1979) OBD PID list. This is a standard set of PIDs that all diagnostic tools must be able to access. The second is a Ford specific (J2190) list which can be accessed by an appropriate diagnostic tool. When accessing any of these PIDs, the values will be continuously updated. The generic or Ford PID list provides definitions and values in appropriate units. For more information, refer to the Society of Automotive Engineers (SAE) document J2205.

All on-board diagnostic (OBD) diagnostic tools display the on-board system readiness (OSR) test. The OSR will display the supported monitors on the vehicle and the status of all monitors (complete or not complete) at that time. Fuel, misfire, and comprehensive component monitors run continuously and always display YES status. Clearing the continuous diagnostic trouble codes (DTCs) and resetting the emission monitors information in the powertrain control module (PCM), or resetting the keep alive memory (KAM) causes the non-continuous monitors to change to a NO status.

Freeze frame data allows access to emission-related values from specific generic PIDs. These values are stored when an emission-related DTC is stored in continuous memory. This provides a snapshot of the conditions that were present when the diagnostic trouble code (DTC) was stored. Once one set of freeze frame data is stored, this data will remain in memory even if another emission-related DTC is stored, with the exception of misfire or fuel system DTCs. Once freeze frame data for a misfire or fuel system DTC is stored, it overwrites any previous data, and freeze frame is no longer overwritten. When a DTC associated with the freeze frame is erased or the DTCs are cleared, new freeze frame data can be stored again. In the event of multiple emission-related DTCs in memory, always note the DTC for the freeze frame data.

FREEZE FRAME DATA

Some unique PIDs are stored in the keep alive memory (KAM) of the PCM to help in diagnosing the root cause of misfires. These PIDs are collectively called misfire freeze frame (MFF) data. These parameters are separate from the generic freeze frame data that is stored for every MIL code. They are used for misfire diagnosis only. The MFF data could be more useful for misfire diagnosis than the generic freeze frame data. It is captured at the time of the highest misfire rate, and not when the DTC is stored at the end of a 1,000 or 200 revolution block. (Generic freeze frame data for misfire can be stored minutes after the misfire actually occurred.)

Note. MFF PIDs are supported on all vehicles, but may not be available on all diagnostic tools because enhanced PID access may vary by diagnostic tool manufacturer.

MISFIRE FREEZE-FRAME PIDs

The output test mode (OTM) aids in diagnosing output actuators associated with the PCM. This mode allows the technician to energize and de-energize most of the system output actuators on command. When entering OTM, the outputs can be turned off and on without activating the fan control. The low and high speed fan control(s) may be turned on separately without energizing the other outputs. This function is supported by each vehicle strategy and may not be available on all diagnostic tools.

As a safety precaution, OTM will default to the off state after 10 minutes and the fuel pump off state after approximately 7-10 seconds. OTM will also turn off after the vehicle is started or after cycling the key OFF then ON.

Note. Clear the continuous diagnostic trouble codes (DTCs) and reset the emission monitors information in the powertrain control module (PCM) was previously called PCM reset.

All OBD diagnostic tools support the clearing of continuous DTCs and resetting of emission monitors information in the PCM.

The clearing of the continuous DTCs allows the diagnostic tool to command the PCM to clear/reset all emission-related diagnostic information. While carrying out this operation a DTC P1000 will be stored in the PCM until all the OBD system monitors or components have been tested to satisfy a drive cycle without any other faults occurring. For more information about a drive cycle, refer to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE .

The following events occur when the continuous DTCs and emission monitors information is cleared from the PCM

1. Clears the number of DTCs.
2. Clears the DTCs.
3. Clears the freeze frame data.
4. Clears the diagnostic monitoring test results.
5. Resets the status of the OBD system monitors.
6. Sets DTC P1000.

Resetting the KAM returns the PCM memory to its default setting. Adaptive learning contents such as idle speed, refueling event, and fuel trim are included. To clear the continuous DTCs in the PCM and have it reset the emissions monitors information, is also part of a KAM reset. Refer to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) . Both can be useful in post repair retest.

After the KAM has been reset, the vehicle may exhibit certain driveability concerns. It is necessary to drive the vehicle to allow the PCM to learn the values for optimum driveability and performance.

This function may not be supported by all diagnostic tools. Refer to the diagnostic tool manufacturer's instruction manual.

If an error message is received or the diagnostic tool does not support this function, disconnecting the battery ground cable for a minimum of 5 minutes may be used as an alternative procedure.

The flash electrically erasable programmable read only memory (EEPROM) is contained in an integrated circuit (IC) internal to the PCM. The EEPROM contains the vehicle strategy including calibration information specific to the vehicle, and is capable of being programmed or flashed repeatedly.

As part of the calibration there is an area referred to as the vehicle identification (VID) block. The VID block is programmed when installing a new PCM as described under Programming the VID Block for a Replacement PCM. Failure to carry out this procedure may generate fault code P1635 or P1639. The VID block in an existing PCM can also be tailored to accommodate various hardware or parameter changes made to the vehicle since production. Failure to carry out this procedure properly may generate fault code P1635, Tire/Axle Ratio out of Acceptable Range. An incorrect tire/axle ratio is one of the main causes for fault code P1639. This is described under Making Changes to the VID Block and also under Making Changes to the PCM Calibration. The VID block contains many items used by the strategy for a variety of functions. Some of these items include the VIN, octane adjust, fuel octane, fuel type, vehicle speed limit, tire size, axle ratio, the presence of speed control, and four wheel drive electronic shift-on-the-fly (ESOF) versus manual shift-on-the-fly (MSOF). Only items applicable to the vehicle hardware and supported by the VID block will display on the diagnostic tool.

When changing items in the VID block, the strategy places range limits on certain items such as tire and axle ratio. The number of times the VID block may be reconfigured is limited. When this limit is reached, the diagnostic tool displays a message indicating the need to flash the PCM again to reset the VID block.

Each of the procedures described below use the Worldwide Diagnostic System (WDS). Programming can be carried out by a local Ford dealer or any non-Ford facility. There are other enhanced diagnostic tools that may have programming capabilities available. Refer to the manufacturer's user manual for details.

Description of On Board Diagnostic (OBD) Drive Cycle

The following procedure is designed to execute and complete the OBD monitors and to clear the Ford P1000, I/M readiness code. To complete a specific monitor for repair verification, follow steps 1 through 4, then continue with the step described by the appropriate monitor found under the OBD Monitor Exercised column. For the EVAP monitor to run, the ambient air temperature must be between 4.4 to 37.8°C (40 to 100°F), and the altitude below 2,438 meters (8,000 feet). If the P1000 code must be cleared in these conditions, the PCM must detect them once (twice on some applications) before the EVAP monitor can be bypassed and the P1000 cleared. The EVAP bypassing procedure is described in the following drive cycle.

The OBD drive cycle will be carried out using a diagnostic tool. Consult the instruction manual for each described function.

Note. A detailed description for clearing the DTCs is found in this article. Refer to CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM) .

Basic circuit checks help to minimize pinpoint test steps by providing a procedure to diagnose harness faults associated with the electronic engine control (EEC) system. The following techniques provide helpful reminders for diagnosing open circuits (continuity), shorts to ground, and shorts to power.

1. The suspect circuit must be isolated before testing.
2. When disconnecting any harness connector, always inspect for damaged or pushed out pins, corrosion, and loose wires. Repair as necessary.
3. The digital multimeter (DMM) must be set to the correct scale.
4. The techniques do not apply in all situations, therefore, it is necessary to follow each pinpoint test step accurately and completely.
5. General resistance and voltage values are specified below. Always use the pinpoint test values if they differ.
6. Always turn the key to the OFF position unless directed otherwise by the pinpoint test.

Each of the following procedures require the powertrain control module (PCM) and component to be disconnected to isolate the harness.

See also:
• TYPICAL DIAGNOSTIC REFERENCE VALUES