1991 LEXUS SC400 Service Repair Manual

Page 3465 of 4087

LEXUS SC400 1991  Service Repair Manual 
OKNG
3Check voltage between terminals HTL1, HTR1 of engine & ECT ECU connector and \
body
ground.
C
OK
Hint
P(1) Connect engine & ECT ECU connector.
(2) Warm up engine to normal operating temperature

Page 3466 of 4087

LEXUS SC400 1991  Service Repair Manual 
±MEMO±TR±67
ENGINE TROUBLESHOOTING 
WhereEverybodyKnowsYourName

Page 3467 of 4087

LEXUS SC400 1991  Service Repair Manual 
Diag. Code 22Water Temp. Sensor Circuit
CIRCUIT DESCRIPTION
Water Temp.°C ( °F)Resistance
(k)Voltage
(V)
±20 (±4)16.04.3
0 (32)5.93.4
20 (68)2.52.4
40 (104)1.21.5
60 (140)0.60.9
80 (176)0.30.5
1

Page 3468 of 4087

LEXUS SC400 1991  Service Repair Manual 
DIAGNOSTIC CHART
HINT: If diagnostic codes º22º (water temperature sensor circuit), º2\
4º (intake air temperature sensorcircuit) and º41º (throttle position sensor circuit) are output\
 simult

Page 3469 of 4087

LEXUS SC400 1991  Service Repair Manual 
NGOK
OKNG
OKNG
INSPECTION PROCEDURE
HINT: If diagnostic codes º22º (water temperature sensor circuit), º2\
4º (intake air temperature sensor cir-cuit) and º41º (throttle position sensor circuit

Page 3470 of 4087

LEXUS SC400 1991  Service Repair Manual 
Diag. Code   22Water Temp. Sensor Circuit
CIRCUIT DESCRIPTION
The water temperature sensor senses the coolant tem-
perature.  A thermistor built in the sensor changes the
resistance value according t

Page 3471 of 4087

LEXUS SC400 1991  Service Repair Manual 
DIAGNOSTIC CHART
DIAGNOSTIC
 CHART
HINT:  If diagnostic codes º22º (water temperature sensor circuit), º\
24º (intake air temperature sensorcircuit) and º41º (throttle position sensor circuit)

Page 3472 of 4087

LEXUS SC400 1991  Service Repair Manual 
NGOK
OKNG
OKNG
INSPECTION PROCEDURE
HINT:  If diagnostic codes º22º (water temperature sensor circuit), º\
24º (intake air temperature sensor circuit)and º41º (throttle position sensor circuit)