Part 5
Part 5 of 6
Continued From Part 4 Part 4
Continuous Memory Self-Test
The continuous memory self-test is a functional test of the PCM carried out under any condition (engine running or off) with the key on. Unlike the KOEO and KOER self-tests, which can only be activated on-demand, the continuous self-test is always active. A concern does not need to be present when accessing continuous memory self-test DTCs, making the test valuable when diagnosing intermittent concerns. The vehicle may need to be driven or the on board diagnostic (OBD) drive cycle completed to allow the PCM to detect a concern. See On Board Diagnostic (OBD) Drive Cycle for more information. When a concern is stored in memory, a DTC is output on the data link when requested by the scan tool.
There are 2 types of continuous DTCs. The first type is an emission-related code which illuminates the malfunction indicator lamp (MIL) in the instrument cluster. The second is a non-emission related, non-MIL code which does not illuminate the cluster indicator.
For emission-related MIL DTCs, the PCM stores the DTC in continuous memory when a concern is detected for the first time. At this point the DTC does not illuminate the MIL and is considered a pending code. The purpose of pending codes is to assist in repair verification by reporting a pending DTC after one drive cycle. If the same concern is detected after the next drive cycle, the emission-related MIL code illuminates the MIL and sets both a confirmed MIL DTC and a permanent DTC. The MIL remains illuminated even if the concern is intermittent. A permanent DTC is stored until three consecutive passing drive cycles have been completed after a repair and the MIL turns off, or after a request to clear DTCs has been made using the scan tool and the next monitoring cycle has completed and passed for that DTC.
Confirmed emission-related MIL DTCs and any non-emission related, non-MIL DTCs are erased approximately 40 vehicle warm-up cycles after the concern was last detected, or if the DTCs are cleared by the scan tool.
Pending emission-related MIL DTCs that never detect a concern on a second consecutive drive cycle (and never light the MIL) are not retained in memory for any number of vehicle warm-up cycles; they are immediately cleared when the next monitoring cycle has completed and passed for that DTC, or until a request to clear DTCs has been made by the scan tool.
Any scan tool that meets OBD requirements can access the continuous memory to retrieve emission-related MIL DTCs. However, not all scan tools access pending and non-emission related, non-MIL DTCs in the same way.
During most diagnostic procedures in this information, it is required that all DTCs be retrieved and cleared. Permanent DTCs cannot be directly cleared by the scan tool. When a scan tool clears DTCs, pending and confirmed DTCs are immediately cleared. Permanent DTCs will not clear until the next monitoring cycle has completed and passed for that DTC. See Powertrain Control Software, Permanent DTC. See Engine OBD II Monitors Consult the instruction manual from the tool manufacturer for specific instructions.
Clear the Continuous DTCs and Reset the Emission Monitors Information in the PCM
Description
All on board diagnostics (OBDII) 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.
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 II system monitors is reset
- DTC P1000 is set
NOTE:This function is carried out only after retrieval of continuous DTCs.
Resetting The Keep Alive Memory (KAM)
Description
Resetting the KAM returns the 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 DTCs in the PCM and reset the emission monitors information, is part of a KAM reset.
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 air conditioning (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.
A KAM Reset is done as follows:
During key on, engine off with the scan tool, use the reset keep alive memory function. This is found in the active command modes menu on the Integrated Diagnostic System (IDS) scan tool.
If a generic scan tool is used, this function may not be supported. See scan tool manufacturer's instruction manual.
If an error message is received or the scan tool does not support this function, disconnecting the negative battery cable for a minimum of 5 minutes may be used as an alternative procedure.
On-Board System Readiness (OSR)
Description
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 run continuously and always display YES status. Clearing the continuous DTCs and resetting the emission monitors information in the 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.
Output State Control (OSC)
Description
WARNING:Safety must be observed when using Output State Control (OSC). Failure to follow these instructions may result in personal injury.
The OSC aids in diagnosing output actuators associated with the 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. The 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 DTCs related to the transmission range (TR) sensor, output shaft sensor (OSS) or the vehicle speed sensor (VSS) must be fixed or the PCM does not allow the OSC to operate.
The OSC has 2 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 that 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.
One Touch Integrated Start System
Some vehicles are equipped with one touch integrated start system. It may be necessary to disable the one touch integrated start system to carry out diagnostic procedures that require extended cranking. Connect the scan tool, access the PCM and select the one touch integrated start system control PID to disable the system.
Output Test Mode (OTM)
Description
The OTM aids in servicing 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 the IDS or equivalent tester and may not be available on all generic scan tools.
As a safety precaution, OTM will default to its normal state after 10 minutes, after the vehicle is started or after cycling the key off then on.
WARNING:Safety must be observed when using output test mode:When all outputs are on, the electric fuel pump is briefly energized, so make sure fuel system is intact and is not being serviced at this time. When low speed or high speed fan control(s) are turned on, make sure 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 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.
Parameter Identification (PID)
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 2 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 Mazda-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 Mazda PID list provides definitions and values in appropriate units. For more information, refer to the Society of Automotive Engineers (SAE) document J2205.
Generic OBD PID List
An X in the Freeze Frame column denotes both a mode 1 and mode 2 PID (real time and freeze frame).
- OL = Open loop, have not satisfied conditions for closed loop.
- Percent engine load adjusted for atmospheric pressure.
- CL = Closed loop using HO2S(s) as feedback for fuel control.
- OL DRIVE = Open loop due to driving conditions (heavy acceleration).
- OL FAULT = Open loop due to fault with all upstream HO2S sensors.
- CL FAULT = Closed loop fuel control, but fault with one upstream HO2S sensor on dual bank vehicles.
Mazda PID List
NOTE:This is not a complete list of Mazda PIDs available. This is a list of Mazda PIDs in this information.
Freeze Frame Data
Description
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 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.
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 scan tools because enhanced PID access may vary by scan tool manufacturer. Misfire Freeze-Frame PIDs
Continued in Part 6 Part 6