Malfunction Indicator Lamp (MIL) Operation

USING CHECK ENGINE/MALFUNCTION INDICATOR LAMP
As a functional test, the malfunction indicator lamp (MIL) illuminates at key-on before engine cranking.

Whenever the powertrain control module (PCM) sets a diagnostic trouble code that effects vehicle emissions, it illuminates the MIL. The PCM illuminates the MIL only for diagnostic trouble codes that effect vehicle emissions. The MIL remains on until the diagnostic trouble code is erased.

On manual transaxle vehicles, the MIL either flashes or illuminates continuously when the PCM detects active engine misfire.

During active misfire, the PCM records the current engine operating conditions. The engine operating conditions recorded by the PCM.

ITEMS INDICATED BY THE CHECK ENGINE/MALFUNCTION INDICATOR LAMP
No cam signal at PCM
Internal controller failure
EGR solenoid circuit
EVAP solenoid circuit
Injector #1 control circuit
Injector #2 control circuit
Injector #3 control circuit
Injector #4 control circuit
Idle air control motor circuit
Intake air temperature sensor voltage to high
Upstream HO2 shorted to voltage
PCM failed SPI communications
Low speed fan control relay circuit
High speed fan control relay circuit
Upstream HO2S response
Upstream HO2S heater failure
Downstream HO2S response
Downstream HO2S heater failure
Throttle position sensor voltage low
Throttle position sensor voltage high
Engine coolant temperature sensor voltage too low
Engine coolant temperature sensor voltage too high
Upstream HO2S stays at center
No vehicle speed sensor signal
MAP sensor voltage too low
MAP sensor voltage too high
No change in MAP from start to run
Ignition coil No.1 primary circuit
Ignition coil No.2 primary circuit
EGR system failed
Intake air temperature sensor voltage too low
Multiple cylinder misfire *
Cylinder #1 misfire *
Cylinder #2 misfire *
Cylinder #3 misfire *
Cylinder #4 misfire *
Catalytic converter efficiency failure
EVAP purge flow monitor failure
Park/Neutral switch failure
Power steering switch failure
Fuel system rich*
Fuel system lean*
Downstream HO2S shorted to voltage
Closed loop temperature not reached
TPS voltage does not agree with MAP
Timing belt skipped 1 tooth or more
Target idle not reached (+/- 2OO RPM)
Intermittent loss of CMP or CKP

NOTES:
1. After the power train control module (PCM) detects a malfunction, the check engine/malfunction indicator lamp illuminates when the engine is next turned on and the same malfunction is re-detected. However, for items marked with an asterisk (*), the check engine/malfunction indicator lamp illuminates on the first detection of the malfunction.

2. After the check engine/malfunction indicator lamp illuminates, it will be switched off under the following conditions.

- When the ECM monitored the powertrain malfunction three times* and detected no malfunction.

* In this case, one time indicates from engine start to stop.

- For misfiring or a fuel trim malfunction, when driving conditions (engine speed, engine coolant temperature, etc.) are similar to those when the malfunction was first recorded.

CAUTION: If the check engine/malfunction indicator lamp illuminates because of a malfunction of the PCM, transmission between the scan tool and the PCM cannot occur. In this case, the diagnostic trouble code cannot be read.