TOYOTA PRIUS 2001 Service Repair Manual

I18377
A/C amplifier
A7
Ambient Temp.
SensorMPX+
A71
1 2 15
MP2+ A74 3 2Combination Meter
MPX+
MPX±GR
GR±B B8 MPX+
MPX±16
B8 Body ECU
GR
1MPX TAM
2MPX E2
14
E10
13
E1023
E8
18
E8 ECM
W±GIA25
IK12W±G GR±L11
4 G1 Gateway ECU
GR±B
2MPD
1MPD
C11
C11
BR
BR±W G1 G1 DI±884
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
DTC 12 Ambient Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the ambient temperature and sends the appropriate signals to the A/C amplifier.
DTC No.Detection ItemTrouble Area

Ambient temperature sensor

Harness or connector between ambient temperature sensor
12Open or short in ambient temperature sensor circuit

Harness or connector between ambient tem erature sensor
and ECM

ECM
ECM

Harness or connector between ECM and A/C amplifier

A/C amplifier.
WIRING DIAGRAM
DI7S6±01

I18175
ON
E2
TA M
(±) (+)
ECM terminals
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±885
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminals TAM and E2 of ECM connector.
PREPARATION:
(a) Remove ECM with connectors still connected.
(b) Turn ignition switch ON.
CHECK:
Check voltage between terminals TAM and E2 of ECM connec-
tor at each temperature .
OK:
Voltage
at 25 °C (77 °F) : 1.35 ± 1.75 V
at 40 °C (104 °F) : 0.85 ± 1.25 V
HINT:
As the temperature increases, the voltage decreases.
NG Go to step 2.
OK
Proceed to the next circuit inspection shown on problem symptoms table (See page DI±874).
However, if DTC 12 is displayed, check and replace A/C amplifier.

I05262
1
2
DI±886
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
2 Check ambient temperature sensor.
PREPARATION:
Disconnect ambient temperature sensor connector.
CHECK:
Check resistance between terminals 1 and 2 of ambient tem-
perature sensor connector at each temperature.
OK:
Resistance
at 25 °C (77 °F) : 1.6 ± 1.8 kW
at 40 °C (104 °F) : 0.5 ± 0.7 kW
HINT:
As the temperature increases, the resistance decreases.
NG Replace ambient temperature sensor.
OK
Check multiplex communication system (See page DI±750).

I18376
A/C Amplifier
W
SGTE 2
A9
1
2 A13
A/C Thermistor
W
TE 1
A9
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±887
2001 PRIUS (RM778U)
DTC 13 Evaporator Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the A/C
amplifier.
DTC No.Detection ItemTrouble Area

Evaporator temperature sensor.
13Open or short in evaporator temperature sensor circuit.
Harness or connector between evaporator temperature sen-
sor and A/C amplifiersor and A/C amplifier.

A/C amplifier.
WIRING DIAGRAM
DI7S7±01

I18161
ON
SGTE TE
(±) (+)
AC0175
Thermometer
Ice
ThermistorOhmmeter
More
than
10 cm
(3.94 in.)
DI±888
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
1 Check voltage between terminals TE and SGTE of A/C amplifier connector.
PREPARATION:
(a) Remove center cluster module control with connectors
still connected.
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals TE and SGTE of A/C am-
plifier connector at each temperature.
OK:
Voltage
at 0 °C (32 °F) : 2.0 ± 2.4 V
at 15 °C (59 °F) : 1.4 ± 1.8 V
HINT:
As the temperature increases, the voltage decreases.
NG Go to step 2.
OK
Proceed to next circuit inspection shown on problem symptoms table (See page DI±874). Howev-
er, if DTC 13 is displayed, check and replace A/C amplifier.
2 Check evaporator temperature sensor.
PREPARATION:
Remove evaporator temperature sensor (See page AC±27).
CHECK:
Check resistance between terminals 1 and 2 of evaporator tem-
perature sensor connector at each temperature.
OK:
Resistance
at 0 °C (32 °F) : 4.6. ± 5.1 kW
at 15 °C (59 °F) : 2.1 ± 2.6 kW
HINT:
As the temperature increases, the voltage decreases.
NG Replace evaporator temperature sensor.
OK

± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±889
2001 PRIUS (RM778U)
3 Check harness and connector between A/C amplifier and evaporator tempera-
ture sensor (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace A/C amplifier.

I18376
ECM
E9 THW14
E2 18 E2
Engine Coolant Temp. SensorW
B±RE9 2
1 DI±890
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
DTC 14 Engine Coolant Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the engine coolant temperature and sends the appropriate signals to the A/C amplifier.
These signals are used for warm up control when the engine is cold.
DTC No.Detection ItemTrouble Area
14Ohtittt iit

Water temperature sensor

Harness or connector between engine coolant temp. sensor
d ECM14Open or short in water temperature sensor circuit.and ECM

Harness or connector between ECM and A/C amplifier

A/C amplifier
WIRING DIAGRAM
DI7S8±01

S05502
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±891
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check engine coolant temp. sensor using hand±held tester.
PREPARATION:
Connect the hand±held tester to the DLC3.
CHECK:
Check the engine coolant temp. sensor using DATA LIST.
OK Check or replace A/C amplifier.
NG
2 Check engine coolant temp. sensor.
PREPARATION:
Remove engine coolant temp. sensor.
CHECK:
Measure resistance between terminals.
OK:
Resistance is within acceptable zone on chart.
Water temperatureResistance
20°C (68°F)2 ± 3 kW
80°C (176°F)0.2 ± 0.4 kW
NG Replace engine coolant temp. sensor.
OK

DI±892
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
3 Check for open and short in harness and connector between ECM and engine
coolant temp. sensor (See page IN±41).
NG Repair or replace harness or connector.
OK
Check multiplex communication system (See page DI±750).

Resistance of photodiode
Strength of solar radiationWeak Strong
High
Low
I18378
A/C Amplifier
A12
A/C Solar
Sensor
A9A9
TSS5TS
5 6
1
2W
W
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±893
2001 PRIUS (RM778U)
DTC 21 Solar Sensor Circuit
CIRCUIT DESCRIPTION
A photo diode in the solar sensor detects solar radiation and
sends signals to the A/C amplifier.
DTC No.Detection ItemTrouble Area
Open or short in solar sensor circuit
Solar sensor
21
Open or short in solar sensor circuit.
(Please note that display of DTC 21 is not abnormal when the
Harness or connector between solar sensor and A/C amplifi-
er(y
sensor is not receiving solar radiation.)er.

A/C amplifier.
WIRING DIAGRAM
DI7S9±01