1991 LEXUS SC300 Service Repair Manual

Page 2697 of 4087

LEXUS SC300 1991  Service Repair Manual 
NGOK
3Check voltage between terminals HTL2, HTR2 of engine & ECT ECU connector and \
body
ground.
C
OK
Hint
P(2) Connect  engine & ECT ECU connector.
(2) Warm up engine to normal operating temperatur

Page 2698 of 4087

LEXUS SC300 1991  Service Repair Manual 
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Page 2699 of 4087

LEXUS SC300 1991  Service Repair Manual 
Diag. Code   31Air Flow Meter Circuit
CIRCUIT DESCRIPTION
As shown in the figure at right, when a pillar (Vortex
generating  body) is placed in the path of a uniform flow,
vortices called Karman±Vor

Page 2700 of 4087

LEXUS SC300 1991  Service Repair Manual 
DIAGNOSTIC CHART
DIAGNOSTIC
 CHART
WIRING DIAGRAM
Check and replace ECU.Replace air flow meter. Check and replace ECU.
Check voltage of air flow meter power source. Check voltage terminal KS of ECU.

Page 2701 of 4087

LEXUS SC300 1991  Service Repair Manual 
NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals KS and E1 of engine & ECT ECU connector.
C
OK
PConnect the check harness A.
(See page TR±30)
Measure voltage between terminals KS and

Page 2702 of 4087

LEXUS SC300 1991  Service Repair Manual 
OKNG
NGOK
3Disconnect air flow meter connector and check voltage between terminals \
KS and E1 of engine
& ECT ECU.
C
OK
PDiconnect the air flow meter connector.
Turn ignition switch on.
Measure volt

Page 2703 of 4087

LEXUS SC300 1991  Service Repair Manual 
Diag. Code    35High Altitude Compensator Sensor
(HAC Sensor) Circuit
CIRCUIT DESCRIPTION
The HAC sensor is built into the ECU. This is a semiconductor pressure sens\
or with properties which cause i

Page 2704 of 4087

LEXUS SC300 1991  Service Repair Manual 
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