Overview
When following powertrain diagnostics on vehicles with on board diagnostic (OBD), the system may be checked by an off-board tester referred to as a scan tool. This article contains information for carrying out diagnostics with a scan tool. A scan tool has certain generic capabilities that are standard across the automotive industry in the United States and Canada. All functions are selected from a menu. Refer to the instruction manual provided by the tool manufacturer.
International Standards Organization (ISO) 14229 DTC Descriptions
The ISO 14229 DTC is a set of common requirements for diagnostic systems. The scan tool displays a failure type and a status type with the DTC. The types display additional information on the scan tool for the condition that set the DTC. For a list of failure type descriptions, refer to «INTERNATIONAL STANDARDS ORGANIZATION (ISO) 14229 DIAGNOSTIC TROUBLE CODE (DTC) DESCRIPTIONS», International Standards Organization (ISO) 14229 Diagnostic Trouble Code (DTC) Descriptions.
Description
All on board diagnostic (OBD) scan tools support the clearing of continuous DTCs and resetting of emission monitors information in the PCM.
The clearing of the continuous DTCs allows the scan tool to command the PCM to clear/reset all emission-related diagnostic information. While carrying out this operation, DTC P1000 is stored in the PCM until all the OBD system monitors or components have been tested to satisfy a drive cycle without any other concerns 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 the emission monitors information is cleared from the PCM
- the number of DTCs is reset
- the DTCs are cleared (on vehicles with permanent DTCs, additional vehicle operation is required to complete and pass the appropriate monitors to complete the clearing of permanent DTCs)
- the freeze frame data is cleared
- the diagnostic monitoring test results are reset
- the status of the OBD system monitors is reset
- DTC P1000 is set
Resetting the KAM returns the powertrain control module (PCM) memory to its default setting. Adaptive learning contents such as adaptive airflow, idle speed, refueling event, and fuel trim are included. Clear the continuous diagnostic trouble codes (DTCs) in the PCM and reset the emission monitors information, is 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 testing.
After the KAM has been reset, the vehicle may exhibit certain driveability concerns. It is necessary to allow the engine to idle at normal operating temperature with the A/C off for 2 minutes. Then drive the vehicle to allow the PCM to learn the values for optimum driveability and performance.
This function may not be supported by all scan tools. Refer to the scan tool manufacturer's instruction manual.
If an error message is received or the scan tool does not support this function, disconnecting the battery ground cable for a minimum of 5 minutes may be used as an alternative procedure on some vehicles.
All on board diagnostic (OBD) scan tools display the on board system readiness (OSR) test. The OSR displays 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 (CCMs) run continuously and always display a 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.
A detailed description of completing the OBD monitors is found, refer to «ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE».
| WARNING | SAFETY MUST BE OBSERVED WHEN USING OSC. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY. |
The OSC aids in diagnosing output actuators associated with the powertrain control module (PCM) for the engine. This mode allows the technician to command the individual actuator state. For example, the output can be enabled or disabled, the duty cycle or the angle of the output can be increased or decreased. OSC is used to help test the electrical, hydraulic or mechanical components of the vehicle. This function is supported by the vehicle strategy but may not be present on all vehicles or available on all scan tools.
Retrieve the continuous codes and carry out a key on, engine off (KOEO) and key on, engine running (KOER) on demand self-test before using any OSC. Any diagnostic trouble codes (DTCs) related to the transmission range (TR) sensor, output shaft speed (OSS) sensor or the vehicle speed sensor (VSS) must be fixed or the PCM does not allow the OSC to operate.
The OSC has two options for operation, the Bench Mode and the Drive Mode. The Bench Mode is functional only when the vehicle gear selector is in the PARK or NEUTRAL position. The Bench Mode may be used when the engine is on (running) or off (not running).
Each OSC function has a unique set of vehicle operating requirements that the technician is required to meet before operating the OSC. If the vehicle requirements are not met while commanding the OSC value, an error message appears. When the error message is received, OSC is canceled.
To confirm the scan tool sent the OSC value and the PCM has accepted the OSC substitution, a corresponding parameter identification (PID) for each OSC parameter must be monitored.
| WARNING | SAFETY MUST BE OBSERVED WHEN USING OTM. WHEN ALL OUTPUTS ARE ON, THE ELECTRIC FUEL PUMP IS BRIEFLY ENERGIZED. MAKE SURE THE FUEL SYSTEM IS INTACT AND IS NOT BEING REPAIRED AT THIS TIME. WHEN LOW SPEED OR HIGH SPEED FAN CONTROL(S) ARE TURNED ON, MAKE SURE THE FAN BLADES ARE CLEAR OF ANY OBSTRUCTION. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY. |
The OTM aids in diagnosing output actuators associated with the powertrain control module (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 controls 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 scan tools.
As a safety precaution, OTM defaults to the off state after 10 minutes, and the fuel pump off state after approximately 7-10 seconds. OTM also turns off after the vehicle is started or after cycling the key OFF then ON.
The PID mode allows access to powertrain control module (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 and both are used throughout this information. The first is the generic (J1979) OBD PID list. This is a standard set of PIDs that all scan tools must be able to access. The second is a Ford specific (J2190) list which can be accessed by an appropriate scan tool. When accessing any of these PIDs, the values are 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.
Freeze frame data allows access to emission-related values from specific generic parameter identification (PID). These values are stored when an emission-related diagnostic trouble code (DTC) is stored in continuous memory. This provides a snapshot of the conditions that were present when the DTC was stored. Once one set of freeze frame data is stored, this data remains 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 data is no longer overwritten. When a DTC associated with the freeze frame data 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.
| Acronym | Description | Measurement Units |
|---|---|---|
| AAT | Ambient Air Temperature | Degrees |
| APP_D | Accelerator Pedal Position D | % |
| APP_E | Accelerator Pedal Position E | % |
| APP_F | Accelerator Pedal Position F | % |
| BARO | Barometric Pressure | KPa |
| CATTEMP11 | Catalyst Temperature Bank 1, Sensor 1 | Degrees |
| CATTEMP21 | Catalyst Temperature Bank 2, Sensor 1 | Degrees |
| CLRDIST | Distance Since Codes Cleared | Km/mi |
| ECT | Engine Coolant Temperature | Degrees |
| EQ_RAT | Commanded Equivalence Ratio | Unit |
| EQ_RAT11 | Lambda Value Bank 1, Sensor 1 | Unit |
| EQ_RAT21 | Lambda Value Bank 2, Sensor 1 | Unit |
| EVAPPCT | Commanded Evaporative Purge | % |
| EVAP_VP | Evaporative System Vapor Pressure | Pa |
| FLI | Fuel Level Input | % |
| FRP | Fuel Rail Pressure | KPa |
| FUELSYS1 | Open/Closed Loop 1 | OL/CL/OL DRIVE/OL FAULT/CL FAULT |
| FUELSYS2 | Open/Closed Loop 2 | OL/CL/OL DRIVE/OL FAULT/CL FAULT |
| IAT | Intake Air Temperature | Degrees |
| LFT1 | Long Term Fuel Bank 1 | % |
| LFT2 | Long Term Fuel Bank 2 | % |
| LOAD | Calculated Load Value | % |
| MAF | Mass Air Flow Rate | G/s |
| MAP | Manifold Absolute Pressure | VOLTS/kPa/ PSI/inHg |
| O2S11 | Bank 1 Upstream Oxygen Sensor (11) | Volts/mA |
| O2S12 | Bank 1 Downstream Oxygen Sensor (12) | Volts |
| O2S21 | Bank 2 Upstream Oxygen Sensor (21) | Volts/mA |
| O2S22 | Bank 2 Downstream Oxygen Sensor (22) | Volts |
| RPM | Engine RPM | RPM |
| RUNTM | Run Time | Seconds |
| SFT1 | Short Term Fuel Bank 1 | % |
| SFT2 | Short Term Fuel Bank 2 | % |
| SPARKADV | Spark Advance | Degrees |
| TAC_ PCT | Commanded Throttle Actuator | % |
| TP | Absolute Throttle Position | % |
| TP_REL | Relative Throttle Position | % |
| VS WARMUPS | Vehicle Speed Number of Warmups Since Code Cleared | Km/h-mph Units |
FREEZE FRAME DATA REFERENCE CHART
Some unique PIDs are stored in the keep alive memory (KAM) of the powertrain control module (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 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, not when the DTC is stored at the end of a 200 or 1,000 revolution block (generic freeze frame data for misfire can be stored minutes after the misfire actually occurred).
The MFF PIDs are supported on all vehicles, but may not be available on all scan tools because enhanced PID access may vary by scan tool manufacturer.
| PID Name | Description | Measurement Units |
|---|---|---|
| MFF_EGR | EGR DPFE sensor at the time of misfire | Volts |
| MFF_IAT | Intake air temperature at the time of misfire | Degrees |
| MFF_INGEAR | Transmission In Gear at Time Of Misfire | Yes/No |
| MFF_LOAD | Engine load at the time of misfire | % |
| MFF_PNP | 1= in DRIVE during the time of misfire | Mode |
| MFF_RNTM | Engine running time at the time of misfire | Time |
| MFF_RPM | Engine RPM at the time of misfire | RPM |
| MFF_RUN | Engine Running Time At Time Of Misfire | Time |
| MFF_SOAK | Engine off soak time at the time of misfire | Time |
| MFF_TCC_ LOCK | Torque Converter Clutch at Time Of Misfire | Yes/No |
| MFF_THR_ ANG | Throttle Angle at Time Of Misfire | % |
| MFF_TP | Throttle Position at time of misfire | Volts |
| MFF_TRIP | Number of driving cycles at the time of misfire (at least one 1,000 rev block) | Number of Trips |
| MFF_VSS MP_ LRN | Vehicle speed at the time of misfire 1= Misfire wheel profile learned in KAM | Km/h-mph Yes/No |
MISFIRE FREEZE FRAME PIDS REFERENCE CHART
The EEPROM is contained in an integrated circuit internal to the powertrain control module (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 DTC 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 DTC P1635, Tire/Axle Ratio out of Acceptable Range. An incorrect tire/axle ratio is one of the main causes for DTC 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 vehicle identification number (VIN), octane adjust, fuel octane, fuel type, vehicle speed limit, tire size, axle ratio, the presence of speed control, and 4-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 are displayed on the scan 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 scan tool displays a message indicating the need to flash the PCM again to reset the VID block.
On selected vehicles equipped with permanent DTC reporting capabilities, neutral profile correction should be learned after a PCM replacement in order to activate the misfire monitor. This can be accomplished using the Misfire Monitor Neutral Profile Learn function on the scan tool.
Programming can be carried out by a local Ford dealer or any non-Ford facility. Refer to the scan tool manufacturer's instruction 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, inspection/maintenance (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 powertrain control module (PCM) must detect them once (twice on some applications) before the EVAP monitor can be bypassed and diagnostic trouble code (DTC) P1000 is cleared. The EVAP bypassing procedure is described in the following drive cycle.
The OBD drive cycle is carried out using a scan tool. Refer to the manufacturer's instruction manual for each described function.
A detailed description for clearing the DTCs is found. Refer to «CLEAR THE CONTINUOUS DIAGNOSTIC TROUBLE CODES (DTCS) AND RESET THE EMISSION MONITORS INFORMATION IN THE POWERTRAIN CONTROL MODULE (PCM)».
See also:
• TYPICAL DIAGNOSTIC REFERENCE VALUES