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Chapter 6 Emissions control systems
*1 Oxy en sensor
*2 Air wow sensor
‘3 Intake air temperature sensor
“4 Engine coolant temperature sensor
“5 Throttle position sensor
“6 idle position switch
“7 Top dead center sensor
“8 Crank angle sensor
‘9 Barometric pressure sensor
*IO EGR temperature sensor
Canister
l
lgnrtion switch - ST
l
Ignition switch - IG,
l
Power supply
l
Vehicle speed sensor
l
Air conditioner switch
0 Power steering oil
pressure switch <AIT>
l
Inhibitor switch <pJT>
*l Injector
*2
Idle speed control servo
*3 Purge control solenoid valve
*4 EGR control solenoid valve
e Fuel pump control (control relay)
l
Air conditioner power relay
0 Ignition timing control
l
Self-diagnosis output
e Malfunction indicator light
Idle speed-control servo
Cl-3 Air flow sensor
, Fast idle air valve
From fuel pump -+
Positrve crankcase
ventilation valve
Fuef ore&&e’reaulator
--+1
lel tank
] Air inlet
Engine coolant
temperature
sensor ’ )s ~
-~
. -.
*3 ’ intake air
temp. sensor
*7 Top dead center
sensor
Catalytrc converter
14.ld Multi-Point
Injection (MPI) system (3.OL California models)
V~C;U$;~ hose color
G: Green
;, Liz;t blue
Yl Yellow
3 Numerous sensors transmit data to the ECU; they include:
Air conditioner switch
Air-flow sensor
Barometricpressure sensor
Coo/ant temperature sensor
Crank angle sensor
EGR temperature sensor (California models)
/d/e position switch
ignition switch
Inhibitor switch (mode/s equipped with an automatic transmission)
Intake air temperature sensor
Motor position sensor (2.4L engine)
Oxygen sensor
Throttle position sensor
Top dead center sensor
Vehicle speed sensor
You can locate these sensors and switches by referring to the accom-
panying illustrations
(see illustrations).
4 The ECU also monitors most of its own input and output circuits. If it
detects a fault somewhere in the MPI system, it stores this information in
its memory. You can often determine the location of a problem, or at least
yhich circuit it’s in, by outputting stored malfunction codes with a voltme-
ter. To learn how to output this information and display it on a voltmeter,
refer to Section 15.
5 t Your first step should be a thorough visual inspection of the vacuum
hoses and electrical connectors in the part of the MPI system that’s mal-
functioning. Make sure everything is properly connected and/or plugged
in. The most common cause of a problem in an MPI system is a loose or
corroded electrical connector or a loose vacuum line. If that doesn’t solve
the problem, you’ll find simple tests of the important information sensorsin
Section 16.
15 Self-diagnosis and malfunction codes (fuel-injected
models only)
Note: To access the code information on 1996 2.4L models, it is neces-
sary to use a the MU J- II Scan Toolandadditionalsupport test equipment.
These tools are very expensive and are not recommended for use by the
home mechanic. If you suspect a problem with the emission related wm-
ponentsona 19962.4Lmode/, have thesystem testedbyadealerservice
department or other repau shop.
Refer to illustrations 15. I, 15.6 and 15.7
1 When a malfunction in the MPI system is detected by the ECU, a mal-
function indicator light
(see illustration)
on the instfument panel comes
on. If the ECU detects that the trouble has disappeared before the ignition
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