Without Scan Tool

Description

The self-diagnosis is useful to diagnose malfunctions in major sensors and actuators of the E.C.C.S. system. There are 5 modes in the self-diagnosis system.





1. Mode I - Mixture ratio feedback control monitor A
^ During closed loop condition: The green inspection lamp turns ON when lean condition is detected and goes OFF by rich condition.
^ During open loop condition: The green inspection lamp remains ON or OFF.

2. Mode II - Mixture ratio feedback control monitor B
The green inspection lamp function is the same as Mode I.
^ During closed loop condition: The red inspection lamp turns ON and OFF simultaneously with the green inspection lamp when the mixture ratio is controlled within the specified value.
^ During open loop condition: The red inspection lamp remains ON or OFF.

3. Mode III - Self Diagnosis
This mode is the same as the former self-diagnosis in self-diagnosis mode.

4. Mode IV - Switches ON-OFF diagnosis
During this mode, the inspection lamps monitor the switch ON-OFF condition.
^ Idle switch
^ Starter switch
^ Vehicle speed sensor

5. Mode V - Real time diagnosis
The moment the malfunction is detected, the display will be presented immediately. That is, the condition at which the malfunction occurs can be found by observing the inspection lamps during driving test.

SWITCHING THE MODES

1. Turn ignition switch "ON".





2. Turn diagnostic mode selector on E.C.U. fully clockwise and wait the inspection lamps flash.





3. Count the number of the flashing time, and after the inspection lamps have flashed the number of the required mode, turn diagnostic mode selector fully counterclockwise immediately.

NOTE:
^ When the ignition switch is turned off during diagnosis, in each mode, and then turned back on again after the power to the E.C.U. has dropped off completely, the diagnosis will automatically return to Mode I.

The stored memory would be lost if:

1. Battery terminal is disconnected.

2. After selecting Mode III, Mode IV is selected. However, if the diagnostic mode selector is kept turned fully clockwise, it will continue to change in the order of Mode I > II > III > IV > V > I ... etc., and in this state the stored memory will not be erased.

CHECK ENGINE LIGHT (For California only)





This vehicle has a check engine light on instrument panel. This light comes ON under the following conditions:

1) When ignition switch is turned "ON" (for bulb check).

2) When systems related to emission performance malfunction in Mode I (with engine running).

^ This check engine light always illuminates and is synchronous with red L.E.D.





^ Malfunction systems related to emission performance can be detected by self-diagnosis, and they are clarified as self-diagnostic codes in Mode III.








Use the following diagnostic flowchart to check and repair a malfunctioning system.
^ After repairs, test drive to check that check engine light does not come on.
^ Test driving modes differ with systems. Read the manual before test driving.

Modes I & II - Mixture Ratio Feedback Control Monitors A & B





In these modes, the control unit provides the Air-fuel ratio monitor presentation and the Air-fuel ratio feedback coefficient monitor presentation.

Mode III - Self-Diagnostic System





The E.C.U. constantly monitors the function of these sensors and actuators, regardless of ignition key position. If a malfunction occurs, the information is stored in the E.C.U. and can be retrieved from the memory by turning on the diagnostic mode selector, located on the side of the E.C.U. When activated, the malfunction is indicated by flashing a red and a green L.E.D. (Light Emitting Diode), also located on the E.C.U. Since all the self-diagnostic results are stored in the E.C.U.'s memory even intermittent malfunctions can be diagnosed. A malfunctioning part's group is indicated by the number of both the red and the green L.E.D.s flashing. First, the red L.E.D. flashes and the green flashes follow. The red L.E.D. refers to the number of tens while the green one refers to the number of units. For example, when the red L.E.D. flashes once and then the green one flashes twice, this means the number "12" showing the air flow meter signal is malfunctioning. In this way, all the problems are classified by the code numbers.
^ When engine fails to start, crank engine more than two seconds before starting self-diagnosis.
^ Before starting self-diagnosis, do not erase stored memory. If doing so, self-diagnosis function for intermittent malfunctions would be lost.

The stored memory would be lost if:
1. Battery terminal is disconnected.
2. After selecting Mode III, Mode IV is selected.

RETENTION OF DIAGNOSTIC RESULTS








The diagnostic result is retained in E.C.U. memory until the starter is operated fifty times after a diagnostic item is judged to be malfunctioning. The diagnostic result will then be cancelled automatically. If a diagnostic item which has been judged to be malfunctioning and stored in memory is again judged to be malfunctioning before the starter is operated fifty times, the second result will replace the previous one. It will be stored in E.C.U. memory until the starter is operated fifty times more.