LEXUS SC400 1991 Service Repair Manual

STANDARD VALUE OF ECM TERMINALS
* Only for USA specification vehicles. TR±38
±
ENGINE TROUBLESHOOTING Standard Value of ECU Terminals
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TR±82
TR±96
TR±104
TR±114
TR±118
TR±120
TR±126
TR±128
TR±132
TR±110
AC±68
ST±13 14
IG±6
IG±7
IG±10
IG±10
EM±22
AT±68
BE±398
IN±32
MATRIX CHART OF PROBLEM SYMPTOMS
When the malfunction code is not confirmed in the diagnostic trouble code ch\
eck and the problem still can not
be confirmed in the basic inspection, then proceed to this step and perfor\
m troubleshooting according to the
numbered order given in the table below.
The circuits indicated by on the matrix chart can be inspected using th\
e TCCS checker.
±
ENGINE TROUBLESHOOTING Matrix Chart of Problem SymptomsTR±39
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LOCATION OF CONNECTORS
Location of Connectors in Engine Compartment
TR±40±
ENGINE TROUBLESHOOTING Location of Connectors
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ENGINE TROUBLESHOOTING Location of ConnectorsTR±41
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Location of Connectors in Instrument Panel
TR±42±
ENGINE TROUBLESHOOTING Location of Connectors
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ENGINE TROUBLESHOOTING Location of ConnectorsTR±43
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Location of Connectors in Instrument Panel (Cont'd)
TR±44±
ENGINE TROUBLESHOOTING Location of Connectors
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Location of Connectors in Body
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ENGINE TROUBLESHOOTING Location of ConnectorsTR±45
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CIRCUIT INSPECTIONDiag. Code 12
RPM Signal Circuit (No. 1)
CIRCUIT DESCRIPTION
The distributor in the Engine Control System contains three pick±up coil\
s (G1, G2 and NE).
The G1, G2 signals inform the ECU of the standard crankshaft angle.
The NE signals inform the ECU of the crankshaft angle and the engine spe\
ed.
 Code No. Diagnostic Code Detecting Condition Trouble Area
  
NoºNEºorºG1ºandºG2ºsignal to ECU within 2
 

Open or short in NE G circuit  No ºNEº or ºG1º and ºG2º signal to ECU within 2
sec after cranking 
Open or short in NE, G circuit.

Distributor
 12 sec. after cranking. 
Distributor

Open or short in STA circuit.
ECU  Open in ºGº
circuit. 
Oen or short in STA circuit.

ECU
TR±46±
ENGINE TROUBLESHOOTING Circuit Inspection
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DIAGNOSTIC CHART
WIRING DIAGRAM
Check resistance of each pickup coils in
distributor
Check for open and short in harness and
connector between ECU and distributor.
Check air gap.
Check and replace ECU.
Replace distributor.
Repair or rep lace harness or connector.
Replace distributor
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±47
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