2001 TOYOTA PRIUS air conditioning

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

I18163
ON
(±)TS
S5TS
(+)
DI±894
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminals S5TS and TS 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 S5TS and TS of A/C ampli-
fier connector when the solar sensor is subjected to an electric
light, and when the sensor is covered by a cloth.
OK:
ConditionVoltage
Sensor subjected to electric lightBelow 4.0 V
Sensor covered by a cloth4.0 ± 4.5 V
HINT:
As the inspection light is gradually moved away from the sen-
sor, the voltage increases.
NG Go to step 2.
NG
Proceed to next circuit inspection shown on problem symptoms table (See page DI±874). Howev-
er, if DTC 21 is displayed, check and replace A/C amplifier.

I00325
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±895
2001 PRIUS (RM778U)
2 Check solar sensor.
PREPARATION:
Remove solar sensor (See page AC±59).
CHECK:
(a) Cover the sensor by a cloth.
(b) Measure resistance between terminals 1 and 2 of solar
sensor connector.
HINT:
Connect positive (+) lead of ohmmeter to terminal 2 and nega-
tive (±) lead to terminal 1 of the solar sensor.
OK:
Resistance : 8W (No continuity)
PREPARATION:
Remove the cloth from the solar sensor and subject the sensor
to electric light.
CHECK:
Measure resistance.
OK:
Resistance : Below 10 kW (Continuity)
HINT:
As the electric light is moved gradually away from the sensor,
the resistance increases.
NG Replace solar sensor.
OK
3 Check harness and connector between A/C amplifier and solar sensor
(See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace A/C amplifier.

I18379
Compressor
Lock SensorA/C Amplifier
4
29
A8LOCK W±L
18
A8SG LOCK IE14
BR±WW±L
W±LIK14
IK15
BR±W BR±W
IE15 DI±896
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
DTC 22 Compressor Lock Sensor Circuit
CIRCUIT DESCRIPTION
This sensor sends 1 pulse par engine revolution to the A/C amplifier. If the number ratio of the compressor
speed divided by the engine speed is smaller than a predetermined value, the A/C amplifier turns the com-
pressor off. And, the indicator flashes at about 1 sec. intervals.
DTC No.Detection ItemTrouble Area
All diti b l d t t d f 3
CompressorAll conditions below are detected for 3 secs. or more.
( ) E i d 450

Com ressor

Compressor drive belt
22(a) Engine speed : 450 rpm or more.
(b) Ratio between engine and compressor speed deviates

Com ressor drive belt

Compressor lock sensor22(b) Ratio between engine and compressor speed deviates
20 % or more in comparison to normal operation

Com ressor lock sensor

Harness or connector between compressor and A/C amplifier 20 % or more in comparison to normal operation.Harness or connector between com ressor and A/C am lifier

A/C amplifier
WIRING DIAGRAM
DI7SA±01

I18005
2
4
N02774
0.2 V/Din.0 V
20 msec/Division (Idling)LCK1 LOCK signal waveform
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±897
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check compressor.
PREPARATION:
(a) Check compressor drive belt tension (See page AC±15).
(b) Check if the compressor does not lock during operation with engine started and blower switch and A/C
switch ON.
NG Adjust drive belt tension or repair compressor.
OK
2 Check compressor lock sensor.
PREPARATION:
Disconnect compressor lock sensor connector.
CHECK:
Measure resistance between terminals 2 and 4 of compressor
lock sensor connector.
OK:
Resistance : at 20 °C (68 °F) : 65 ± 125 W
Reference : Inspection using oscilloscope
During cranking or idling, measure voltage between terminals
LOCK and SGLOCK of A/C amplifier.
HINT:
The correct waveform appears as shown in the illustration on
the left.
NG Replace compressor.
OK