On Board Diagnostic System Function
ON BOARD DIAGNOSTIC SYSTEM FUNCTIONThe on board diagnostic system has the following four functions.
Operation Of MIL ( Malfunction Indicator Light):
1. BULB CHECK : This function checks the MIL bulb for damage (blown, open circuit, etc.).
2. MALFUNCTION WARNING: This is a usual driving condition. When a malfunction is detected twice (two trip detection logic), the MIL will light up to inform the driver that a malfunction has been detected.
Only the following malfunctions will light up or blink the MIL even in the 1st trip.
- "Misfire (Possible three way catalyst damage)"
- "Three way catalyst function"
- "Closed loop control"
3. SELF-DIAGNOSTIC RESULTS: This function allows diagnostic trouble codes to be read.
4. FRONT HEATED OXYGEN SENSOR MONITOR: This function allows the fuel mixture condition (lean or rich), monitored by front heated oxygen sensor, to be read.
HOW TO SWITCH DIAGNOSTIC TEST MODES
Part 1 Of 2:
Part 2 Of 2:
- Switching the modes is not possible when the engine is running.
- When the ignition switch is turned off during diagnosis, power to the ECM will drop off after approx. 5 seconds. The diagnosis mode will automatically return to On Board Diagnostic Test Mode I. But stored codes will remain in memory unless the erasing procedure has been performed.
DIAGNOSTIC TEST MODE I-BULB CHECK
In this mode, the MALFUNCTION INDICATOR LAMP on the instrument panel should stay ON. If it remains OFF, check the bulb.
DIAGNOSTIC TEST MODE I-MALFUNCTION WARNING
Meaning Of MIL ( Malfunction Indicator Light):
- These Diagnostic Trouble Code Numbers are clarified below in Diagnostic Test Mode II (SELF-DIAGNOSTIC RESULTS).
DIAGNOSTIC TEST MODE II-SELF-DIAGNOSTIC RESULTS
In this mode, a diagnostic trouble code is indicated by the number of blinks of the MALFUNCTION INDICATOR LAMP as shown below.
Wavelength For Codes P0102 And P0403:
Wavelength For Code P1003:
Long (0.6 second) blinking indicates the number of ten digits, and short (0.3 second) blinking indicates the number of single digits. For example, the malfunction indicator lamp blinks 10 times for 6 seconds (0.6 sec x 10 times) and then it blinks three times for about 1 second (0.3 sec x 3 times). This indicates the DTC "1003" and refers to the malfunction of the park/neutral position switch.
In this way, all the detected malfunctions are classified by their diagnostic trouble code numbers. The DTC "0505" refers to no malfunction.
HOW TO ERASE DIAGNOSTIC TEST MODE II (Self-diagnostic results)
The diagnostic trouble code can be erased from the backup memory in the ECM when the diagnostic test mode is changed from Diagnostic Test Mode II to Diagnostic Test Mode I. (Refer to "HOW TO SWITCH DIAGNOSTIC TEST MODES" explained earlier).
- If the battery terminal is disconnected, the diagnostic trouble code will be lost from the backup memory within 24 hours.
- Be careful not to erase the stored memory before starting trouble diagnoses.
DIAGNOSTIC TEST MODE II-FRONT HEATED OXYGEN SENSOR MONITOR
In this mode, the MALFUNCTION INDICATOR LAMP displays the condition of the fuel mixture (lean or rich) which is monitored by the front heated oxygen sensor.
Conditions:
To check the front heated oxygen sensor function, start engine in Diagnostic Test Mode II. Then warm it up until engine coolant temperature indicator points to middle of gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Make sure that the MALFUNCTION INDICATOR LAMP comes ON more than 5 times within 10 seconds with engine running at 2,000 rpm under no-load.