DTC 0205

Note: Refer to TSB #98-039




SYSTEM DESCRIPTION
This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which bypasses the throttle valve via IACV-AAC valve. The IACV-AAC valve opens and closes according to the signal sent from the ECM. The camshaft position sensor detects the actual engine speed and sends a signal to the ECM. The ECM then controls the IACV-AAC valve so that engine speed coincides with the target value memorized in ECM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is determined by taking into consideration various engine conditions, such as during warm up, deceleration, and engine load (air conditioner, power steering and cooling fan operation).




COMPONENT DESCRIPTION
IACV-AAC Valve
The IACV-AAC valve is moved by open and close signals from the ECM. When the open signal is sent to the valve, the amount of air that will flow through the valve increases. The more air that flows through the valve, the higher the idle speed. When the close signal is sent to the valve, the amount of air decreases.




CONSULT REFERENCE VALUE IN DATA MONITOR MODE




ECM TERMINALS AND REFERENCE VALUE
Specification data are reference values and are measured between each terminal and (43) (ECCS ground).




ON BOARD DIAGNOSIS LOGIC

DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
Procedure for Malfunction A
With Consult
(1) Turn ignition switch "ON".
(2) Select "DATA MONITOR" mode with CONSULT.
(3) Start engine and run it at idle at least 2 seconds.

OR

With GST
(1) Start engine and run it at idle for at least 2 seconds.
(2) Select "MODE 3" with GST.

OR

No Tools
(1) Start engine and run it at idle at least 2 seconds.
(2) Perform "Diagnostic Test Mode II" (Self-diagnostic results) with ECM.

Procedure for malfunction B
With Consult
(1) Start engine and warm it up sufficiently.
(2) Turn ignition switch "OFF" and wait at least 5 seconds.
(3) Turn ignition switch "ON" again and select "DATA MONITOR" mode with CONSULT.
(4) Start engine and run it at least 30 seconds at idle speed.

OR

With GST
(1) Start engine and warm it up sufficiently.
(2) Turn ignition switch "OFF" and wait at least 5 seconds.
(3) Start engine again and run it at least 30 seconds at idle speed.
(4) Select "MODE 3" with GST.

OR

No Tools
(1) Start engine and warm it up sufficiently.
(2) Turn ignition switch "OFF" and wait at least 5 seconds.
(3) Start engine again and run it at least 30 seconds at idle speed.
(4) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(5) Perform "Diagnostic Test Mode II" (Self-diagnostic results) with ECM.




DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION
IACV-AAC Valve
With Consult
1. Disconnect IACV-AAC valve harness connector.




2. Check resistance between terminals (2) and (3), (3) and (4).

Resistance: 50 - 100 ohms [at 25°C (77°F)]

3. Reconnect IACV-AAC valve harness connector.
4. Start engine and warm it up sufficiently.




5. Perform "IACV-AAC/V OPENING" in "ACTIVE TEST" mode with CONSULT.
6. Check "MAS AIR/FL SE" value during changing the valve opening from 20% to 80%.
"MAS AIR/FL SE" value should be increased more than 0.15V.
7. If NG, replace IACV-AAC valve.

NOTE: Do not use "FUNCTION TEST" mode with CONSULT.

OR

Without Consult
1. Disconnect IACV-AAC valve harness connector.
2. Check resistance between terminals (2) and (3), (3) and (4).

Resistance: 50 - 100 Ohms [at 25°C (77°F)]

3. If NG, replace IACV-AAC valve.