1991 LEXUS SC400 check engine

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Page 2711 of 4087

LEXUS SC400 1991  Service Repair Manual 
Diag. Code   43Starter Signal Circuit
CIRCUIT DESCRIPTION
When the engine is cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture is therefore
necessary  in order to ach

Page 2712 of 4087

LEXUS SC400 1991  Service Repair Manual 
NGOK
OKNG
v
INSPECTION PROCEDURE
1Check output condition of diag. code 43.
C
OK
P
OK
C
Setting the test mode.
(2) Turn ignition switch OFF.
(2) Connect terminals TE2 and E1 of TDCL.
(2) Turn ignition

Page 2714 of 4087

LEXUS SC400 1991  Service Repair Manual 
CIRCUIT DESCRIPTION (Contd)
DIAGNOSIS CODE DETECTION DRIVING PATTERN
Purpose of the driving pattern.
(a)  To simulate diag. code detecting condition after diag. code is recorded.
(b)  To check that

Page 2715 of 4087

LEXUS SC400 1991  Service Repair Manual 
DIAGNOSTIC CHART
HINT:  If diag. code 52 is displayed, check No. 1 knock sensor (for left bank)\
 circuit.If diag. code 55 is displayed, check No. 2 knock sensor (for right bank\
) circuit.
If diag.

Page 2716 of 4087

LEXUS SC400 1991  Service Repair Manual 
NGOK
OKNG
INSPECTION PROCEDURE
1Check continuity between terminals KNK1, KNK2 of engine & ECT ECU connector and body
ground.
C
OK
P(2) Connect  the Check Harness A.(See page  TR±30)
(2) Disconnect t

Page 2717 of 4087

LEXUS SC400 1991  Service Repair Manual 
OKNG
NOYES
3
Check for open and short in harness and connectors between engine & ECT ECU a\
nd knock
sensor (See page IN±27)
Repair or replace harness or connector.
4Does malfunction disappear when

Page 2720 of 4087

LEXUS SC400 1991  Service Repair Manual 
CIRCUIT DESCRIPTION (Contd)
DIAGNOSIS CODE DETECTION DRIVING PATTERN
Purpose  of the driving pattern.
(a)  To simulate diag. code detecting condition after diag. code is recorded.
(b)  To check that

Page 2721 of 4087

LEXUS SC400 1991  Service Repair Manual 
DIAGNOSTIC CHART
WIRING DIAGRAM
Check voltage of terminal EGR 1 ~ 4.
Check voltage of EGR Step motor power
source.
Check resistance of EGR step motor.
Check for open and short in harness and
connecto