Page 2657 of 4087
Location of Connectors in Body
TR±46±
ENGINE TROUBLESHOOTING Locations of Connectors
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Page 2658 of 4087
±MEMO ±
±
ENGINE TROUBLESHOOTINGTR±47
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Page 2659 of 4087

CIRCUIT INSPECTIONDiag. Code 12
RPM Signal Circuit (No.1)
CIRCUIT DESCRIPTION
Cam position sensors (G1 and G2 signals) and engine speed sensor (NE sig\
nal) consist of a signal plate
and a pick up coil.
The G1, G2 signal plates have one tooth each on its outer circumference and\
are mounted on the left and
right bank camshafts.
When the camshafts rotate, the protrusion on the signal plate and the air gap on the pick up coil change,
causing fluctuations in the magnetic field and generating an electromotive forc\
e in the pick up coil.
The NE signal plate has 12 teeth and is mounted on the crankshaft. The NE s\
ignal sensor generates 12
NE signals per engine revolution. The ECU detects the standard crankshaf\
t angle based on the G1, G2
signals, and the actual crankshaft angle and the engine speed by the NE \
signals.
Code No.Diagnostic Code Detecting ConditionTrouble Area
wOpen or short in engine speed sensor, No. 1,w Oen or short in engine s eed sensor, No. 1,
No. 2 cam position sensor circuit
12No ºNEº or ºG1º and ºG2º signal to ECU
No. 2 cam osition sensor circuit
w Engine speed sensor12No NE or G1 and G2 signal to ECU
within 2 sec. after cranking.
wEngine s eed sensor
wNo. 1, No. 2 cam position sensorgNo. 1, No. 2 cam osition sensor
wStarter
wECU
TR±48±
ENGINE TROUBLESHOOTING Circuit Inspection
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Page 2660 of 4087
DIAGNOSTIC CHART
WIRING DIAGRAM
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±49
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Page 2661 of 4087
OKNG
INSPECTION PROCEDURE
1Check engine speed sensor, No. 1, No. 2 cam position sensor
C
OK
PFor engine speed sensor.
(2) Remove engine under cover.
(2) Disconnected engine speed sensor connector.
For No.1, No. 2 cam position sensor,
(2) Disconnect No. 1, No. 2 cam poisition sensor con-nectors.
Measure resistance of engine speed sencor, No. 1 and
No. 2 cam position sensor.
Replace engine speed sensor, No. 1, No. 2 cam poistion
sensor.
TR±50
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ENGINE TROUBLESHOOTING Circuit Inspection
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Page 2662 of 4087
OKNG
OKNG
2Check for open and short in harness and connector between engine & ECT ECU an\
d each sen-
sor (See page IN±27).
Repair or replace harness or connector.
3Inspect sensor installation and teeth of signal plate.
Tighen the sensor.
Replace signal plate.
Check and replace engine and ECT ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±51
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Page 2663 of 4087

Diag. Code 13RPM Signal Circuit (No.2)
CIRCUIT DESCRIPTION
Refer to RPM signal circuit (No. 1) on page TR±48.
Code No.Diagnostic Code Detecting ConditionTrouble Area
No NE signal to ECU for 0.1 sec. or more at
1,000 rpm or more.
wOpen or short in engine speed sensor
w circuit.
w Engine speed sensor
w ECU
13No 12 pulses of NE to ECU during the interval
between G1 and G2 pulses.
wOpen or short in engine speed sensor
w circuit.
w Mechanical system malfunction (skipping
teeth of timing belt, belt stretched)
w Engine speed sensor
w ECU
Deviation in G (G1, G2) and NE signal contin-
ues for 1 sec. during idling (throttle fully
closed) after engine warmed up.wMechanical system malfunction (skipping
teeth of timing belt, belt stretched)
w No. 1, No. 2 cam position sensor
w ECU
DIAGNOSTIC CHARTDIAGNOSTIC CHART
Inspect sensor installation. Check if any teeth of NE
signal plate are broken
Check valve timing (Check for loose and jumping teeth
of timing belt (See page EM±51)). Tighten the sensor.
Replace signal plate.
Adjust valve timing
(Repair or replace timing belt).
HINT: Perform troubleshooting of diag. code 12 first. If no trouble is found, trouble\
shoot the following mechanical systems.
Check for momentary interruption
(See page TR±23).
TR±52±
ENGINE TROUBLESHOOTING Circuit Inspection
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Page 2664 of 4087
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ENGINE TROUBLESHOOTINGTR±53
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