ON BOARD DIAGNOSTIC (OBD) SYSTEM

Diagnosis Description

INTRODUCTION
The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actuators. The ECM also records various emission-related diagnostic information including:

• 1st trip DTC No. is the same as DTC No.
• Output of a DTC indicates a malfunction. However, GST and the Diagnostic Test Mode II do not indicate whether the malfunction is still occurring or has occurred in the past and has returned to normal. CONSULT-III can identify malfunction status as shown below. Therefore, using CONSULT-III (if available) is recommended.

How to Erase DTC and 1st Trip DTC
With CONSULT-III

NOTE:

• If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10 seconds and then turn it ON (engine stopped) again.
• If the DTC is not for CVT related items (see See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection), skip step 1.

1. Erase DTC in TCM. Refer to See: Transmission and Drivetrain\Continuously Variable Transmission/Transaxle\Testing and Inspection\Component Tests and General Diagnostics\CVT RE0F09B.
2. Select "ENGINE" with CONSULT-III.
3. Select "SELF-DIAG RESULTS".
4. Touch "ERASE". (DTC in ECM will be erased.) WITH GST

NOTE:

• If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10 seconds and then turn it ON (engine stopped) again.

1. Select Service $04 with GST (Generic Scan Tool). No Tools

NOTE:

• If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once. Wait at least 10 seconds and then turn it ON (engine stopped) again.

1. Erase DTC in ECM. Refer to How to Erase Diagnostic Test Mode II (Self-diagnostic Results).

• If the battery is disconnected, the emission-related diagnostic information will be cleared within 24 hours.
• The following data are cleared when the ECM memory is erased.
• Diagnostic trouble codes
• 1st trip diagnostic trouble codes
• Freeze frame data
• 1st trip freeze frame data
• System readiness test (SRT) codes
• Test values Actual work procedures are explained using a DTC as an example. Be careful so that not only the DTC, but all of the data listed above, are cleared from the ECM memory during work procedures.

SYSTEM READINESS TEST (SRT) CODE
System Readiness Test (SRT) code is specified in Service $01 of SAE J1979.
As part of an enhanced emissions test for Inspection and Maintenance (I/M), certain states require the status of
SRT be used to indicate whether the ECM has completed self-diagnosis of major emission systems and components. Completion must be verified in order for the emissions Inspection to proceed.
If a vehicle is rejected for a State emissions Inspection due to one or more SRT items indicating "INCMP", use the information to set the SRT to "CMPLT".
In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT status will indicate "CMPLT" for each application system. Once set as "CMPLT", the SRT status remains "CMPLT" until the self-diagnosis memory is erased.
Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customer's normal driving pattern; the SRT will indicate "INCMP" for these items.

NOTE:
The SRT will also indicate "INCMP" if the self-diagnosis memory is erased for any reason or if the ECM memory power supply is interrupted for several hours.
If, during the state emissions Inspection, the SRT indicates "CMPLT" for all test items, the inspector will continue with the emissions test. However, if the SRT indicates "INCMP" for one or more of the SRT items the vehicle is returned to the customer untested.

NOTE:
If MIL is ON during the state emissions Inspection, the vehicle is also returned to the customer untested even though the SRT indicates "CMPLT" for all test items. Therefore, it is important to check SRT ("CMPLT") and
DTC (No DTCs) before the Inspection.

SRT Item
The table below shows required self-diagnostic items to set the SRT to "CMPLT".

• The SRT will indicate "CMPLT" at the time the respective self-diagnosis have one (1) OK result.
• The emissions Inspection requires "CMPLT" of the SRT only with OK self-diagnosis results.
• During SRT driving pattern, the 1st trip DTC (NG) is detected prior to "CMPLT" of SRT and the self-diagnosis memory must be erased from the ECM after repair.
• If the 1st trip DTC is erased, all the SRT will indicate "INCMP".

NOTE:
SRT can be set as "CMPLT" together with the DTC(s). Therefore, DTC check must always be carried out prior to the state emission Inspection even though the SRT indicates "CMPLT".

SRT Service Procedure
If a vehicle has failed the state emissions Inspection due to one or more SRT items indicating "INCMP", review the flowchart diagnostic sequence.

1. Turn ignition switch ON and wait 20 seconds.
2. SRT status is indicated as shown below.

• When all SRT codes are set, MIL illuminates continuously.
• When any SRT codes are not set, MIL will flash periodically for 10 seconds.

1. The MIL will illuminate when the ignition switch is turned ON without the engine running. This is a bulb check. If the MIL does not illuminate, check MIL circuit. Refer to See: Component Tests and General Diagnostics\Malfunction Indicator Lamp (MIL)\Component Function Check.
2. When the engine is started, the MIL should turn off. If the MIL remains on, the on board diagnostic system has detected an engine system malfunction.

On Board Diagnostic System Function
The on board diagnostic system has the following three functions.

• It is better to count the time accurately with a clock.
• It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a malfunction.
• ECM always returns to Diagnostic Test Mode I after the ignition switch is turned OFF. HOW TO SET DIAGNOSTIC TEST MODE II (SELF-DIAGNOSTIC RESULTS)

1. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
2. Repeat the following procedure quickly five times within 5 seconds.

• Fully depress the accelerator pedal.
• Fully release the accelerator pedal.

3. Wait 7 seconds, fully depress the accelerator pedal and keep it depressed for approx. 10 seconds until the MIL starts blinking.
4. Fully release the accelerator pedal. ECM has entered to Diagnostic Test Mode II (Self-diagnostic results).

NOTE:
Wait until the same DTC (or 1st trip DTC) appears to completely confirm all DTCs.

1. Set ECM in Diagnostic Test Mode II (Self-diagnostic results). Refer to "How to Set Diagnostic Test Mode II (Self-diagnostic Results)".
2. Fully depress the accelerator pedal and keep it depressed for more than 10 seconds. The emission-related diagnostic information has been erased from the backup memory in the ECM.
3. Fully release the accelerator pedal, and confirm the DTC 0000 is displayed.

• If the battery is disconnected, the DTC will be lost from the backup memory within 24 hours.
• Do not erase the stored memory before starting trouble diagnosis.

OBD System Operation Chart

Relationship Between MIL, 1st Trip DTC, DTC, and Detectable Items

• When a malfunction is detected for the first time, the 1st trip DTC and the 1st trip freeze frame data are stored in the ECM memory.
• When the same malfunction is detected in two consecutive trips, the DTC and the freeze frame data are stored in the ECM memory, and the MIL will come on.
• The MIL will turn off after the vehicle is driven 3 times (driving pattern B) with no malfunction. A drive is counted only when the recorded driving pattern is met (as stored in the ECM). If another malfunction occurs while counting, the counter will reset.
• The DTC and the freeze frame data will be stored until the vehicle is driven 40 times (driving pattern A) without the same malfunction recurring (except for Misfire and Fuel Injection System). For Misfire and Fuel Injection System, the DTC and freeze frame data will be stored until the vehicle is driven 80 times (driving pattern C) without the same malfunction recurring. The "TIME" in "SELF-DIAGNOSTIC RESULTS" mode of CONSULT-III will count the number of times the vehicle is driven.
• The 1st trip DTC is not displayed when the self-diagnosis results in OK for the 2nd trip.

Summary Chart

• The B counter will be cleared when the malfunction is detected once regardless of the driving pattern.
• The B counter will be counted up when driving pattern B is satisfied without any malfunction.
• The MIL will turn off when the B counter reaches 3. (*2 in "OBD SYSTEM OPERATION CHART")

[Driving Pattern C]
Driving pattern C means operating vehicle as per the following:
The following conditions should be satisfied at the same time:
Engine speed: (Engine speed in the freeze frame data) ±375 rpm
Calculated load value: (Calculated load value in the freeze frame data) X (1 ±0.1) [%]
Engine coolant temperature (T) condition:

• When the freeze frame data shows lower than 70°C (158°F) , T should be lower than 70°C (158°F) .
• When the freeze frame data shows higher than or equal to 70°C (158°F) , T should be higher than or equal 70 °C (158°F). Example:

If the stored freeze frame data is as per the following:
Engine speed: 850 rpm, Calculated load value: 30%, Engine coolant temperature: 80°C (176°F)
To be satisfied with driving pattern C, the vehicle should run under the following conditions:
Engine speed: 475 - 1,225 rpm, Calculated load value: 27 - 33%, Engine coolant temperature: more than 70°C
(158°F)

• The C counter will be cleared when the malfunction is detected regardless of vehicle conditions above.
• The C counter will be counted up when vehicle conditions above are satisfied without the same malfunction.
• The DTC will not be displayed after C counter reaches 80.
• The 1st trip DTC will be cleared when C counter is counted once without the same malfunction after DTC is stored in ECM.

Relationship Between MIL, DTC, 1st Trip DTC and Driving Patterns Except For "Misfire [Exhaust Quality Deterioration]", "Fuel Injection System"

• The A counter will be cleared when the malfunction is detected regardless of (1) - (4).
• The A counter will be counted up when (1) - (4) are satisfied without the same malfunction.
• The DTC will not be displayed after the A counter reaches 40.

[Driving Pattern B]
Driving pattern B means operating vehicle as per the following:
All components and systems should be monitored at least once by the OBD system.

• The B counter will be cleared when the malfunction is detected once regardless of the driving pattern.
• The B counter will be counted up when driving pattern B is satisfied without any malfunctions.
• The MIL will turn off when the B counter reaches 3 (*2 in OBD SYSTEM OPERATION CHART).