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CIRCUIT DESCRIPTION
When the engine is cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture
is therefore necessary in order to achieve good startability. While the engine is being cranked, the
battery positive voltage is applied to terminal STA of the ECM. The starter signal is mainly used to
increase the fuel injection volume for the starting injection control and after±start injection control.
DIAGNOSTIC CHART
HINT: This diagnostic chart is based on the premise that the engine is cranked normally. If the
engine is not cranked, proceed to the matrix chart of problem symptoms on page EG1±327, w
Open or short in starter signal circuit.
wOpen or short in ignition switch or starter
relay circuit.
wECM
Check for open in harness and connector
between ECM and relay.Proceed to next circuit inspection
shown on matrix chart (See page
E±G±327). Diagnostic Trouble Code Detecting Condition
Repair or replace harness or
connector.
WIRING DIAGRAM
No starter signal to ECM.
Check and replace ECM.Check for the test mode.Trouble Area
DTC 43 Starter Signal Circuit
DTC No.
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Setting the test mode.
(1) Turn ignition switch OFF.
(2) Connect terminals TE2 and E1 of DLC2.
(3) Turn ignition switch ON.
(Don't start the engine)
(4) Connect terminals TE1 and E1 of DLC2.
Check for open in harness and connector between engine control
module and starter relay (See page IN±31). Check output condition of diagnostic trouble code 43.
Proceed to next circuit inspection shown on
matrix chart (See page EG1±327).
Check and replace engine control module.Repair or replace harness or connector.
INSPECTION PROCEDURE
Check if code ª43º is output by the malfunc-
tion indicator lamp.
Code ª43º is output.
Start the engine.
Check if the code ª43º disappear.
Code ª43º is not output.
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If the ECM detects the above diagnosis conditions, it operates the fail safe function in which the
corrective retard angle value is set to the maximum value.
DIAGNOSIS TROUBLE CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is
recorded.
(b) To check that the malfunction is corrected when the repair is completed confirming that diag-
nostic trouble code is no longer detected.
Start engine and warm up.
After engine is warmed up, let it idle for 3 min.
With the A/C ON, perform quick racing (5,000 rpm) 3 times.
(Rapidly depress the accelerator pedal and suddenly release it.)
HINT: If a malfunction exists, the malfunction indicator lamp will light up when sudden
racing is performed.
NOTICE: If the conditions in this test are not strictly followed, detection of the mal-
function will not be possible.
CIRCUIT DESCRIPTION
Knock sensor is fitted the cylinder block to detect engine knocking. This sensor contains a piezoelec-
tric element which generates a voltage when it becomes deformed, which occurs when the cylinder
block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.
w
Open or short in knock sensor circuit.
wKnock sensor (looseness)
wECM Open or short in knock sensor circuit with engine
speed between 1,200 rpm and 6,000 rpm.
Malfunction: Open or Short in Knock Sensor
Diagnostic Trouble Code Detecting Condition
Trouble Area
DTC 52 Knock Sensor Circuit
DTC No.
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Does malfunction disappear when a good knock
sensor is installed? Check for open and short in harness and
connector between knock sensor and ECM.Repair or replace harness or
connector. Check no continuity of knock sensor circuit.
DIAGNOSTIC CHART
WIRING DIAGRAM
Check and replace ECM.Replace knock sensor.Replace knock sensor. Check knock sensor.
YES
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(1) Remove glove compartment.
(See page EG1±234)
(2) Disconnect the engine control module con±
nector.
Check continuity between terminal KNK of engine control module
connector and body ground.
INSPECTION PROCEDURE
Go to step Measure resistance between terminal KNK
of engine control module connector and
body ground.
Resistance: 1 M or higher
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Disconnect knock sensor connector.
Check for open and short in harness and connector between engine
control module and knock sensor (See page IN±31).
Does malfunction disappear when a good knock sensor is installed?
Check and replace engine control module.Replace knock sensor (See page EG1±93).
Replace knock sensor (See page EG1±93). Repair or replace harness or connector.
Check knock sensor.
YES
Measure resistance between the knock
sensor terminal and body.
Resistance: 1 M or higher
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wSpread the time on the horizontal axis, and
confirm that period of the wave is 132
sec.
(Normal mode vibration frequency of knock
sensor: 7.6 KHz).
HINT: If normal mode vibration frequency is not 7.6
KHz, the sensor is malfunctioning.wWith the engine racing (4,000 rpm) measure
waveform between terminal KN K of engine
control module and body ground.
HINT: The correct waveform appears as shown in the
illustration on the left.
INSPECTION USING OSCILLOSCOPE Reference
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CIRCUIT DESCRIPTION
The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the
driving conditions, into the intake air mixture to slow down combustion, reduce the combustion
temperature and reduces NOx emissions. The amount of EGR is regulated by the EGR vacuum
modulator according to the engine load.
If even one of the following conditions is fulfilled,
the VSV is turned ON by a signal from the ECM.
This results in atmospheric air acting on the EGR
valve, closing the EGR valve and shutting off the
exhaust gas (EGR cut±OFF).
Under the following conditions, EGR is cut to
maintain driveability.
wEngine coolant temp. below 60C (140F).
wDuring deceleration (throttle valve closed).
wLight engine load (amount of intake air very
small).
wEngine speed over 4,400 rpm.
wEngine racing.
EG R gas temp. is 70C (158F) or below for 50
sec. under conditions (a) and (b).
(2 trip detection logic) *
(a) Engine coolant temp.: 80C (176F) or more.
(b) EGR operation possible (EX. A/T in 3rd speed
(5th for M/T), 55 ± 60 mph (88 ± 96 km/h),
Flat road).wOpen in EGR gas temp. sensor circuit.
wShort in VSV circuit for EGR.
wEGR hose disconnected, valve stuck.
wClogged EGR gas passage.
wECM Diagnostic Trouble Code Detecting Condition
*: See page
EG1±307.Trouble Area DTC No.
DTC 71 EGR System Malfunction
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