
Idle Air Control Valve (IACV) Ð Auxiliary Air
Control (AAC) Valve
SYSTEM DESCRIPTION
Camshaft position sensorcEngine speed
ECM
(ECCS
control
module)
cIACV-AAC valve
Mass air flow sensorcAmount of intake air
Engine coolant temperature sensor
cEngine coolant temperature
Ignition switch
cStart signal
Throttle position sensor
cThrottle position
Neutral position switch
cNeutral position
Air conditioner switch
cAir conditioner operation
Power steering oil pressure switch
cPower steering load signal
Battery
cBattery voltage
Vehicle speed sensor
cVehicle speed
This system automatically controls engine idle speed to a specified level. Idle speed is controlled through
fine adjustment of the amount of air which by-passes the throttle valve via IACV-AAC valve. The IACV-AAC
valve repeats ON/OFF operation 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 ON/OFF time
of the IACV-AAC valve so that engine speed coincides with the target value memorized in ECM. The tar-
get 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 and power steering operation).
COMPONENT DESCRIPTION
IACV-ACC valve
The IACV-AAC valve is moved by ON/OFF pulses from the
ECM. The longer the ON pulse, the greater the amount of air that
will flow through the valve. The more air that flows through the
valve, the higher the idle speed.
SEF040E
TROUBLE DIAGNOSIS FOR NON-DETECTABLE ITEMSKA
EC-131

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK OVERALL FUNCTION.
1. Start engine and warm it up suffi-
ciently.
2. Perform ``IACV-AAC/V SYS-
TEM'' in ``FUNCTION TEST''
mode with CONSULT.
----------------------------------------------------------------------------------------------------------------------------------OR----------------------------------------------------------------------------------------------------------------------------------
2. Perform ``IACV-AAC/V OPEN-
ING'' in ``ACTIVE TEST'' mode
with CONSULT.
3. Check engine speed varies cor-
responding to IACV-AAC
VALVE opening percent.
----------------------------------------------------------------------------------------------------------------------------------OR----------------------------------------------------------------------------------------------------------------------------------
2. Check idle speed.
800 50 rpm
If NG, adjust idle speed.
3. Stop engine and disconnect
throttle position sensor sub-
harness connector.
4. Restart engine and let it idle
after revving it to 2,000 - 3,000
rpm a few times.
5. Check idle speed again.
750 25 rpm
NG
cOK
INSPECTION END
CHECK POWER SUPPLY.
1. Stop engine.
2. Disconnect IACV-AAC valve harness
connector.
3. Turn ignition switch ``ON''.
4. Check voltage between terminal
V3
and ground with CONSULT or tester.
Voltage: Battery voltage
OK
cNG
Check the following.
l10A fuse
lHarness connectorsF54,M48(RHD mod-
els)
lHarness for open or
short between IACV-
AAC valve and fuse
If NG, repair harness or
connectors.
VA
SEF152U
MEF176E
SEF164U
SEF148U
SEF095U
.
.
.
TROUBLE DIAGNOSIS FOR NON-DETECTABLE ITEMSKA
Idle Air Control Valve (IACV) Ð Auxiliary Air
Control (AAC) Valve (Cont'd)
EC-134

Trouble Diagnoses
Symptom Possible causes Repair order
Radio inoperative (no digital
display and no sound from
speakers).1. 10A fuse
2. Poor radio case ground
3. Radio1. Check 10A fuse (No.
18, located in fuse block). Turn igni-
tion switch ON and verify battery positive voltage is present
at terminal
V10of radio.
2. Check radio case ground.
3. Remove radio for repair.
Radio controls are operational,
but no sound is heard from
any speaker.1. Radio output
2. Radio1. Check radio output voltages.
2. Remove radio for repair.
Radio presets are lost when
ignition switch is turned OFF.1. 7.5A fuse
2. Radio1. Check 7.5A fuse (No.
6, located in fuse block) and verify
battery positive voltage is present at terminal
V6of radio.
2. Remove radio for repair.
Individual speaker is noisy or
inoperative.1. Speaker
2. Radio output
3. Speaker circuit
4. Radio1. Check speaker.
2. Check radio output voltages.
3. Check wires for open or short between radio and speaker.
4. Remove radio for repair.
Radio stations are weak or
noisy.1. Antenna
2. Poor radio ground
3. Radio1. Check antenna.
2. Check radio ground.
3. Remove radio for repair.
Radio generates static noise
with engine running.1. Poor radio ground
2. Loose or missing ground bonding straps
3. Ignition condenser or rear window defogger
noise suppressor condenser
4. Alternator
5. Ignition coil or secondary wiring
6. Radio1. Check radio ground.
2. Check ground bonding straps.
3. Replace ignition condenser or rear window defogger noise
suppressor condenser.
4. Check alternator.
5. Check ignition coil and secondary wiring.
6. Remove radio for repair.
Radio generates static noise
with accessories on (switch
pops and motor noise).1. Poor radio ground
2. Antenna
3. Accessory ground
4. Faulty accessory1. Check radio ground.
2. Check antenna.
3. Check accessory ground.
4. Replace accessory.
SPEAKER INSPECTION
1. Disconnect speaker harness connector.
2. Measure the resistance between speaker terminals
V1andV2.
lThe resistance should be2-4W.
3. Using jumper wires, momentarily connect a 9V battery between speaker terminals
V1andV2.
lA momentary hum or pop should be heard.
ANTENNA INSPECTION
Using a jumper wire, clip an auxiliary ground between antenna and body.
lIf reception improves, check antenna ground (at body surface).
lIf reception does not improve, check main feeder cable for short circuit or open circuit.
RADIO INSPECTION
All voltage inspections are made with:
lIgnition switch ON or ACC
lRadio ON
lRadio connected (If removed for inspection, supply a ground to the case using a jumper wire.)
AUDIO
EL-142

A
A/C HFC134a (R134a) system precaution .....HA-2
A/C HFC134a (R134a) system service
procedure ................................................. HA-48
A/C HFC134a (R134a) system service
tools............................................................ HA-8
A/C HFC134a system service
equipment precaution .............................. HA-10
A/C air flow .................................................. HA-14
A/C component layout ................................. HA-13
A/C compressor clutch removal and
installation ................................................ HA-60
A/C compressor precaution ........................... HA-6
A/C compressor special service tool ............. HA-6
A/C control linkage adjustment
(manual A/C) ............................................ HA-45
A/C control operation (manual A/C) ............ HA-16
A/C diagnostic work flow
(manual A/C) ............................................ HA-17
A/C lubricant (R134a) .................................. HA-50
A/C operational check ................................. HA-18
A/C performance chart ................................ HA-26
A/C performance test diagnoses ................. HA-24
A/C relay ...................................................... HA-44
A/C switch.............................................. HA-16, 43
A/C symptom chart (manual A/C) ............... HA-20
A/C trouble diagnoses (manual A/C)........... HA-17
AAC/V - Wiring diagram ............................ EC-133
ABS (anti-lock brake system) ...................... BR-32
ABS - Wiring diagram .................................. BR-42
Accelerator control system............................. FE-1
Accelerator wire adjustment........................... FE-2
Air bag disposal ........................................... RS-14
Air bag precautions ......................................... GI-1
Air bag ........................................................... RS-6
Air bleeding (hydraulic clutch)........................ CL-5
Air bleeding for brake system........................ BR-4
Air cleaner filter replacement
(KA24 engine).......................................... MA-19
Air cleaner filter replacement
(TD25 engine).......................................... MA-29
Air conditioner cut control ............................ EC-18
Air flow meter - See Mass air flow
sensor ...................................................... EC-89
Alternator ...................................................... EL-41
Angular tightening application ....................... EM-1
Antenna ...................................................... EL-146
Anti-lock brake system - Wiring
diagram .................................................... BR-42
Audio and A/C control removal and
installation - See Instrument panel .......... BT-12
Auto-lock free-running hub........................... FA-15
Auxiliary air control (AAC) valve................ EC-131
Axle housing (rear) ........................................ RA-5
B
Back window .................................................BT-24Back-up lamp switch (M/T)............................ MT-9
Ball joint front axle ....................................... FA-34
Battery .......................................................... EL-18
Baulk ring (M/T) (FS5R30A)........................ MT-36
Baulk ring (M/T) (FS5W71C)....................... MT-15
Blower motor................................................ HA-43
Blower resistor ............................................. HA-43
Body alignment ............................................ BT-43
Body mounting ............................................. BT-41
Boring/horning cylinder block ...................... EM-41
Brake booster .............................................. BR-15
Brake fluid change ......................................... BR-3
Brake fluid level and line check..................... BR-3
Brake fluid level ........................................... MA-35
Brake hydraulic line ....................................... BR-5
Brake inspection .......................................... MA-36
Brake lines and cables inspection .............. MA-35
Brake lining wear temporary checking ........ MA-37
Brake master cylinder .................................. BR-12
Brake pedal.................................................. BR-10
Bulb specifications...................................... EL-252
Bumper, front ................................................. BT-5
Bumper, rear .................................................. BT-8
C
CHARGE - Wiring diagram ...........................EL-34
CIGAR - Wiring diagram ............................ EL-133
CLOCK - Wiring diagram ........................... EL-134
CMPS - Wiring diagram............................... EC-85
CONSULT for ECCS ................................... EC-45
CONSULT general information ..................... GI-34
Cab body ...................................................... BT-40
Camshaft inspection (KA24 engine) ........... EM-28
Camshaft inspection (TD25 engine) ........... EM-85
Camshaft position sensor (CMPS) .............. EC-82
Canister - See EVAP canister ..................... EC-19
Center bearing assembly
(propeller shaft) ........................................ PD-10
Center bearing disassembly
(propeller shaft) .......................................... PD-9
Center case (Transfer) ................................... TF-8
Charging system .......................................... EL-34
Chassis and body maintenance .................. MA-32
Cigarette lighter .......................................... EL-133
Circuit breaker .............................................. EL-13
Clock........................................................... EL-134
Clutch cover ................................................. CL-13
Clutch disc.................................................... CL-12
Clutch fluid level .......................................... MA-32
Clutch master cylinder ................................... CL-6
Clutch operating cylinder ............................... CL-8
Clutch pedal ................................................... CL-4
Clutch release bearing ................................... CL-9
Clutch release mechanism............................. CL-9
Clutch withdrawal lever .................................. CL-9
Collision diagnosis (2WD models)............... RS-21
Collision diagnosis (4WD models)............... RS-42
ALPHABETICAL INDEX
IDX-2

Trouble Diagnoses
Symptom Possible causes Repair order
Radio inoperative (no digital
display and no sound from
speakers).1. 10A fuse
2. Poor radio case ground
3. Radio1. Check 10A fuse (No.
18, located in fuse block). Turn igni-
tion switch ON and verify battery positive voltage is present
at terminal
V10of radio.
2. Check radio case ground.
3. Remove radio for repair.
Radio controls are operational,
but no sound is heard from
any speaker.1. Radio output
2. Radio1. Check radio output voltages.
2. Remove radio for repair.
Radio presets are lost when
ignition switch is turned OFF.1. 7.5A fuse
2. Radio1. Check 7.5A fuse (No.
6, located in fuse block) and verify
battery positive voltage is present at terminal
V6of radio.
2. Remove radio for repair.
Individual speaker is noisy or
inoperative.1. Speaker
2. Radio output
3. Speaker circuit
4. Radio1. Check speaker.
2. Check radio output voltages.
3. Check wires for open or short between radio and speaker.
4. Remove radio for repair.
Radio stations are weak or
noisy.1. Antenna
2. Poor radio ground
3. Radio1. Check antenna.
2. Check radio ground.
3. Remove radio for repair.
Radio generates static noise
with engine running.1. Poor radio ground
2. Loose or missing ground bonding straps
3. Ignition condenser or rear window defogger
noise suppressor condenser
4. Alternator
5. Ignition coil or secondary wiring
6. Radio1. Check radio ground.
2. Check ground bonding straps.
3. Replace ignition condenser or rear window defogger noise
suppressor condenser.
4. Check alternator.
5. Check ignition coil and secondary wiring.
6. Remove radio for repair.
Radio generates static noise
with accessories on (switch
pops and motor noise).1. Poor radio ground
2. Antenna
3. Accessory ground
4. Faulty accessory1. Check radio ground.
2. Check antenna.
3. Check accessory ground.
4. Replace accessory.
SPEAKER INSPECTION
1. Disconnect speaker harness connector.
2. Measure the resistance between speaker terminals
V1andV2.
lThe resistance should be2-4W.
3. Using jumper wires, momentarily connect a 9V battery between speaker terminals
V1andV2.
lA momentary hum or pop should be heard.
ANTENNA INSPECTION
Using a jumper wire, clip an auxiliary ground between antenna and body.
lIf reception improves, check antenna ground (at body surface).
lIf reception does not improve, check main feeder cable for short circuit or open circuit.
RADIO INSPECTION
All voltage inspections are made with:
lIgnition switch ON or ACC
lRadio ON
lRadio connected (If removed for inspection, supply a ground to the case using a jumper wire.)
AUDIO
EL-142