Test Mode Functions

ON BOARD DIAGNOSTIC SYSTEM FUNCTION
The on board diagnostic system has the following functions.

Diagnostic Test Mode I
1. BULB CHECK :
This function checks the bulb for damage (blown, open circuit, etc.) of the malfunction indicator lamp.
- If the MIL does not come on, check MIL circuit and ECM test mode selector.
2. MALFUNCTION WARNING :
This is a usual driving condition. When a malfunction is detected twice (2 trip detection logic), the malfunction indicator lamp 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)"
- "Closed loop control"
- "Fail-safe mode" [except for crankshaft position sensor (REF) circuit]

Diagnostic Test Mode II
1. SELF-DIAGNOSTIC RESULTS :
By using this function, the diagnostic trouble codes can be read.
2. FRONT HEATED OXYGEN SENSOR MONITOR :
In this mode, the fuel mixture condition (lean or rich) monitored by front heated oxygen sensor can be read.






MIL flashing without DTC
If the ECM is in Diagnostic Test Mode II, the MIL may flash when the engine is running. In this case, check ECM test mode selector following "HOW TO SWITCH DIAGNOSTIC TEST MODES".


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
These Diagnostic Trouble Code Numbers are clarified in Diagnostic Test Mode II (SELF-DIAGNOSTIC RESULTS).






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.
To check the front heated oxygen sensor function, start engine in the Diagnostic Test Mode II and warm it up until engine coolant temperature indicator points to the middle of the gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Then 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.






How to switch monitored sensor from left bank to right bank or vice versa
- The following procedure should be performed while the engine is running.
1. Turn diagnostic test mode selector on ECM fully clockwise.
2. Wait at least 2 seconds.
3. Turn diagnostic test mode selector on ECM fully counterclockwise.