Lexus SC300 / Lexus SC400. Manual — part 665
CIRCUIT INSPECTION
Diag. Code 12
RPM Signal Circuit (No.1)
CIRCUIT DESCRIPTION
Cam position sensors (G1 and G2 signals) and engine speed sensor (NE signal) 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 force in the pick up coil.
The NE signal plate has 12 teeth and is mounted on the crankshaft. The NE signal sensor generates 12
NE signals per engine revolution. The ECU detects the standard crankshaft 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 Condition
Trouble Area
•
Open or short in engine speed sensor, No. 1,
•
O en or short in engine s eed sensor, No. 1,
No. 2 cam position sensor circuit
12
No ”NE” or ”G1” and ”G2” signal to ECU
No. 2 cam osition sensor circuit
•
Engine speed sensor
12
No NE or G1 and G2 signal to ECU
within 2 sec. after cranking.
•
Engine s eed sensor
•
No. 1, No. 2 cam position sensor
g
No. 1, No. 2 cam osition sensor
•
Starter
•
ECU
TR–48
–
ENGINE TROUBLESHOOTING
Circuit Inspection
DIAGNOSTIC CHART
WIRING DIAGRAM
–
ENGINE TROUBLESHOOTING
Circuit Inspection
TR–49
OK
NG
INSPECTION PROCEDURE
1
Check engine speed sensor, No. 1, No. 2 cam position sensor
C
OK
P
For 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
–
ENGINE TROUBLESHOOTING
Circuit Inspection
OK
NG
OK
NG
2
Check for open and short in harness and connector between engine & ECT ECU and each sen-
sor (See page
Repair or replace harness or connector.
3
Inspect sensor installation and teeth of signal plate.
Tighen the sensor.
Replace signal plate.
Check and replace engine and ECT ECU.
–
ENGINE TROUBLESHOOTING
Circuit Inspection
TR–51
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст