Lexus SC300 / Lexus SC400. Manual - part 859

Location of Connectors in Instrument Panel (Cont’d)

TR–44

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ENGINE TROUBLESHOOTING

Location of Connectors

Location of Connectors in Body

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ENGINE TROUBLESHOOTING

Location of Connectors

TR–45

CIRCUIT INSPECTION

Diag. Code 12

RPM Signal Circuit (No. 1)

CIRCUIT DESCRIPTION

The distributor in the Engine Control System contains three pick–up coils (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 speed.

ÑÑÑÑÑ

ÑÑÑÑÑ

Code No.

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Diagnostic Code Detecting Condition

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Trouble Area

ÑÑÑÑÑ

ÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

No ”NE” or ”G1” and ”G2” signal to ECU within 2

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Open or short in NE G circuit

ÑÑÑÑÑ

ÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

No ”NE” or ”G1” and ”G2” signal to ECU within 2
sec after cranking

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

 Open or short in NE, G circuit.

 Distributor

ÑÑÑÑÑ

ÑÑÑÑÑ

12

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

sec. after cranking.

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

 Distributor

 Open or short in STA circuit.

ECU

ÑÑÑÑÑ

ÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

Open in ”G” 

 circuit.

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

ÑÑÑÑÑÑÑÑÑÑÑÑÑÑ

 O en or short in STA circuit.

 ECU

TR–46

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ENGINE TROUBLESHOOTING

Circuit Inspection

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

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ENGINE TROUBLESHOOTING

Circuit Inspection

TR–47