1991 LEXUS SC400 oil change

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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30
ELECTRICAL WIRING ROUTING
Position of Parts in Body
A 30 ABS Speed Sensor Rear LH D 10 Door Lock Motor, Door Unlock Detection SW and
A 31 ABS Speed Sensor Rear RH Door Open Detection SW LH
A 32 Auto Antenna Motor and Relay D 11 Door Lock Motor, Door Unlock Detection SW andDoor Open Detection SW RH
C 20 CD Automatic Changer D 12 Driving Position Memory and Return SW
C 21 CD Automatic Changer
C 22 Choke Coil F 11 Front Door Speaker LH F 12 Front Door Speaker RH
D 4 DAY/NIGHT Shift SW F 14 Fuel Lid Opener Solenoid
D 5 Door Courtesy Light LH F 15 Fuel Pump
D 6 Door Courtesy Light RH F 16 Fuel Pump ECU
D 7 Door Key Lock and Unlock SW LH F 17 Fuel Sender
D 8 Door Key Lock and Unlock SW RH F 18 Fuel Sender
D 9 Door Lock Control SW RH H 8 High Mount Stop Light (w/o Rear Spoiler)
H 9 High Mount Stop Light (w/ Rear Spoiler)
L 2 Licence Plate Light
L 3 Light Failure Sensor
L 4 Luggage Compartment Door Opener Motor
L 5 Luggage Compartment Key Unlock SW
L 6 Luggage Compartment Light SW
L 7 Luggage Compartment Light
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