TOYOTA PRIUS 2001 Service Repair Manual

DI7S2±01
DI±874
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
DIAGNOSTIC TROUBLE CODE CHART
DTC No.
(See Page)Detection ItemTrouble Area
11*1
(DI±876)Room temp. sensor circuit

Room temp. sensor

Harness or connector between room temp. sensor and A/C
amplifier

A/C amplifier
12*2
(DI±879)Ambient temp. sensor circuit

Ambient temp. sensor

Harness and connector between ambient temp. sensor and
ECM

ECM

Harness and connector between ECM and A/C amplifier

A/C amplifier
13
(DI±882)Evaporator temp. sensor circuit

Evaporator temp. sensor

Harness and connector between evaporator temp. sensor
and A/C amplifier

A/C amplifier
14
(DI±885)Engine coolant temp. sensor circuit

Water temp. sensor

Harness and connector between engine coolant temp. sensor
and ECM

ECM

Harness and connector between ECM and A/C amplifier
21*3
(DI±888)Solar sensor circuit

Solar sensor

Harness or connector between room temp. sensor and A/C
amplifier

A/C amplifier
22*4
(DI±891)
All conditions below are detected for 3 sec. or more
(g) Engine speed: 500 rpm or more
(h) Ratio between engine and compressor rpm deviates 20 %
or more in comparison to normal operation
Compressor drive belt

Compressor lock sensor

Compressor

Harness and connector between compressor lock sensor and
A/C amplifier
23
(DI±894)
Open in pressure switch circuit
Abnormal refrigerant pressure
[below 196 kPa (2.0 kgf/cm
2, 28 psi) over
3,140 kPa (32.0 kgf/cm2, 455 psi)]

Pressure switch

Harness or connector between pressure switch and A/C am-
plifier

A/C amplifier
31
(DI±897)Air mix damper position sensor circuit

Air mix control servomotor

Harness or connector between air mix control servomotor
and A/C amplifier

A/C amplifier
32
(DI±900)Air inlet damper position sensor circuit

Air inlet control servomotor

Harness or connector between air inlet control servomotor
and A/C amplifier

A/C amplifier
33
(DI±903)Air outlet damper position sensor circuit

Air outlet control servomotor

Harness or connector between air outlet control servomotor
and A/C amplifier

A/C amplifier
41
(DI±906)Air mix control servomotor circuit

Air mix control servomotor

Air mix damper position sensor

Harness or connector between air mix control servomotor
and A/C amplifier

A/C amplifier

± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±875
2001 PRIUS (RM778U)42
(DI±909)
Air inlet control servomotor circuit

Air inlet control servomotor

Air inlet damper position sensor

Harness or connector between air inlet control servomotor
and A/C amplifier

A/C amplifier
43
(DI±912)Air outlet control servomotor circuit

Air outlet control servomotor

Air outlet damper position sensor

Harness or connector between air outlet control servomotor
and A/C amplifier

A/C amplifier
HINT:

*1: If the room temp. is approx. ±18.6°C (±3.7°F) or lower, trouble code 11 may be output even though
the system is normal.

*2: If the ambient temp. is approx. ±52.9°C (±61.4°F) or lower, a malfunction code may be output even
though the system is normal.

*3: If the check is being performed in a dark place, DTC 21 (solar sensor circuit abnormal) could be
displayed.

*4: To confirm DTC 22, perform the following steps.
(1) With the engine is running, enter the DTC check mode.
(2) Enter actuator check mode and set the operation to step NO. 1.
(3) Check that the DTC 22 is output.

DI7S4±01
I18176
A9 A8 A7 DI±876
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
TERMINALS OF ECU
Symbols (Terminals No.)Wiring ColorConditionSTD Voltage (V)
IG eGND
(A7±1 e A7±7)R e W±BIG ON.10 ± 14
BLW e GND
(A7±3 e A7±7)V e W±BIG ON. Blower motor: OperatePulse generation
MP2+ e GND
(A7±4 e A7±7)GR±B e W±BIG ON.Pulse generation
GND e Body ground
(A7±7 e Body ground)W±B e
Body groundAlwaysContinuity
+B e GND
(A7±8 e A7±7)R±G e W±BAlways10 ± 14
IDH e GND
(A8±10 e A7±7)
Y e W±B
IG ON. Head lamp: ON
Rear defogger: ON
Set temp.: MAX. HOT
10 ± 14
Y e W±B
IG ON. Head lamp: OFF
Rear defogger: OFFBelow 1.0
MPX+ e GND
(A7±11 e A7±7)GR e W±BIG ON.Pulse generation
RF e GND
(A8±1 e A7±7)RWWB
Start engine. Water temp.: Below 90°C
Refrigerant pressure: Below 1,520 kPa10 ± 14(A8±1 e A7±7)R±W e W±BStart engine. Water temp.: Approx. 90°C
Refrigerant pressure: Above 1,520 kPaBelow 1.0
CF e GNDVYWBStart engine. A/C compressor: ONBelow 1.0CF e GND
(A8±2 e A7±7)V±Y e W±BStart engine. A/C compressor: OFF10 ± 14
WP e GND
(A8±3 e A7±7)LRWB
Engine speed: Above 500 rpm
Blower motor: OperateBelow 1.0(A8±3 e A7±7)L±R e W±BEngine speed: Above 500 rpm
Blower motor: Not operate10 ± 14
NE e GND
(A8±4 e A7±7)LG e W±BStart enginePulse generation
ACT e GND
(A8±5 e A7±7)P±G e W±BEngine speed: Idle speed10 ± 14
HTR0 e GND
(A8±6 e A7±7)
P±B e W±B
Start engine
Head lamp: OFF
Rear defogger: OFF
Set temp.: MAX. WARM
Blower mode dial: HI
Mode selector: F/D
Water temp.: Below 55 °C
Below 0.7

± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±877
2001 PRIUS (RM778U) LOCk e SGLOCK
(A8±9 e A7±18)
W±L e BR±WStart engine. A/C compressor ON.Pulse generation
MGC e GNDLG RWBStart engine. A/C compressor: ONBelow 1.0MGC e GND
(A8±11 e A7±7)LG±R e W±BStart engine. A/C compressor: OFF10 ± 14
PSW e GND
(A8±11 e A7±7)L±Y e W±BA/C refrigerant pressure: less than 0.19 Mpa (2.0 kgf/cm2) or
more than 3.14 Mpa (3,140 kgf/cm2)
From 10 ± 14 to
Below 1.0
HTR2 e GND
(A8±13 e A7±7)
P e W±B
Start engine
Head lamp: OFF
Rear defogger: OFF
Set temp.: MAX. WARM
Blower mode dial: HI
Mode selector: F/D
Water temp.: 55 ± 70°C
Below 0.7
SGLOCK e GND
(A8±18 e A7±7)BR±W e W±BAlwaysContinuity
TE e SGTEWWIG ON. Ambient temp. 25°C (77°F)1.35 ± 1.75TE e SGTE
(A9±1 e A9±2)W e WIG ON. Ambient temp. 40°C (104°F)0.85 ± 1.25
SGTE e GND
(A9±2 e A7±7)W e W±BAlwaysContinuity
SGTR e GND
(A9±3 e A7±7)W e W±BAlwaysContinuity
TR e SGTRWWIG ON. Room temp. 25°C (77°F)1.8 ± 2.2TR e SGTR
(A9±4 e A9±3)W e WIG ON. Room temp. 40°C (104°F)1.2 ± 1.6
TS e S5TSWWIG ON. Solar sensor subject to electric light1.0 or moreTS e S5TS
(A9±5 e A9±6)W e WIG ON. Solar sensor cover by a clothBelow 1.0
S5TS e GND
(A9±6 e A7±7)W e W±BIG ON.4.5 ± 5.5
S5TPM e SGTPM
(A9±7 e A9±9)W e WIG ON.4.5 ± 5.5
TPM e SGTPMWWIG ON. Mode selector: FACEBelow 1.0TPM e SGTPM
(A9±8 e A9±9)W e WIG ON. Mode selector: DEF4.5 ± 5.5
SGTPM e GND
(A9±9 e A7±7)W e W±BAlwaysContinuity
AOF e GNDWWBIG ON. Mode selector: FACE10 ± 14AOF e GND
(A9±10 e A7±7)W e W±BIG ON. Mode selector: DEFBelow 1.0
AOD e GNDWWBIG ON. Mode selector: FACEBelow 1.0AOD e GND
(A9±11 e A7±7)W e W±BIG ON. Mode selector: DEF10 ± 14
AMH e GNDWWBIG ON. Set temp.: Max. COOL10 ± 14AMH e GND
(A9±13 e A7±7)W e W±BIG ON. Set temp.: Max. WARMBelow 1.0
AMC e GNDWWIG ON. Set temp.: Max. COOLBelow 1.0AMC e GND
(A9±14 e A7±7)W e WIG ON. Set temp.: Max. WARM10 ± 14
SGTP e GND
(A9±15 e A7±7)W e W±BAlwaysContinuity
TP e SGTPWWIG ON. Set temp.: Max. COOLBelow 1.0TP e SGTP
(A9±16 e A9±15)W e WIG ON. Set temp.: Max. WARM4.5 ± 5.5
S5TP e SGTP
(A9±17 e A9±15)W e WIG ON.4.5 ± 5.5
S5TPI e SGTPI
(A9±18 e A9±20)W e WIG ON.4.5 ± 5.5

DI±878
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U) TPI e SGTPI
WWIG ON. Air intake selector: FRESHBelow 1.0TPI e SGTPI
(A9±19 e A9±20)W e WIG ON. Air intake selector: RECIRCULATE4.5 ± 5.5
SGTPI e GND
(A9±20 e A7±7)W e W±BAlwaysContinuity
AIR e GNDWWBIG ON. Air intake selector: FRESHBelow 1.0AIR e GND
(A9±21 e A7±7)W e W±BIG ON. Air intake selector: RECIRCULATE10 ± 14
AIF e GNDWWBIG ON. Air intake selector: FRESH10 ± 14AIF e GND
(A9±22 e A7±7)W e W±BIG ON. Air intake selector: RECIRCULATEBelow 1.0

DI7S3±01
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±879
2001 PRIUS (RM778U)
PROBLEM SYMPTOMS TABLE
SymptomSuspect AreaSee page
Whole function of the does not operate3. A/C amplifier
4. IG power source circuitIN±41
DI±916
Air Flow Control: No blower operation1. IG power source circuit
2. Heater main relay circuit
3. Blower motor circuit
4. A/C amplifierDI±916
DI±921
DI±924
IN±41
Air Flow Control: No blower control1. Heater main relay circuit
2. Blower motor circuit
3. A/C amplifierDI±921
DI±924
IN±41
Air Flow Control: Insufficient air flow1. Blower motor circuitDI±924
Temperature Control: No cool air comes out1. Refrigerant volume
2. Drive belt tension
3. Refrigeration system inspection with manifold gauge set
4. Compressor circuit
5. Pressure switch circuit
6. Compressor lock sensor circuit
7. Air mix damper position sensor circuit
8. Air mix damper control servomotor circuit
9. Room temperature sensor circuit
10.Ambient temperature sensor circuit
11. A/C amplifierAC±3
AC±15
AC±3
DI±927
DI±894
DI±891
DI±897
DI±906
DI±874
DI±879
IN±41
Temperature Control: No warm air comes out1. Air mix damper position sensor circuit
2. Air mix damper control servomotor circuit
3. DC/DC converter circuit
4. PTC heater circuit
5. Room temperature sensor circuit
6. Ambient temperature sensor circuit
7. Evaporator temperature sensor circuit
8. A/C amplifierDI±897
DI±906
DI±934
DI±937,
DI±942
DI±876
DI±882
DI±885
IN±41
Temperature Control: Output air is warmer or cooler that the set
temperature or response is slow1. Refrigerant volume
2. Drive belt tension
3. Refrigeration system inspection with manifold gauge set
4. Radiator fan and condenser fan circuit
5. Solar sensor circuit
6. Room temperature sensor circuit
7. Ambient temperature sensor circuit
8. Evaporator temperature sensor circuit
9. Air mix damper position sensor circuit
10.Air mix damper control servomotor circuit
11. Evaporator
12.Heater radiator
13.Expansion valve
14.A/C amplifierAC±3
AC±15
AC±3
DI±947
DI±888
DI±876
DI±879
DI±885
DI±897
DI±906
AC±28
AC±28
AC±52
IN±41
Temperature Control: No temperature control (only Max. cool or
Max. warm)1. Room temperature sensor circuit
2. Ambient temperature sensor circuit
3. Air mix damper position sensor circuit
4. Air mix damper control servomotor circuit
5. A/C amplifierDI±876
DI±882
DI±897
DI±906
IN±41
No air inlet control1. Air inlet damper position sensor circuit
2. Air inlet damper control servomotor circuit
3. A/C amplifierDI±900
DI±909
IN±41

DI±880
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U) Engine idle up does not occur, or is continuous
1. Compressor circuit
2. A/C amplifierDI±927
IN±41
Blinking of A/C indicator1. Compressor lock sensor circuit
2. A/C amplifierDI±891
IN±41

DI7S5±01
I18376
A/C Amplifier
W
SGTR 3
A9
2
1 A11
A/C Room Temp.
Sensor
W
TR 4
A9
± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±881
2001 PRIUS (RM778U)
CIRCUIT INSPECTION
DTC 11 Room Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the temperature inside the cabin and sends the appropriate signals to the A/C amplifier.
DTC No.Detection ItemTrouble Area

Room temperature sensor.
11Open or short in room temperature sensor circuit.
Harness or connector between room temp. sensor and A/C
amplifieramplifier.

A/C amplifier.
WIRING DIAGRAM

I18162
ON
SGTR
TR
(±) (+)
I00317
DI±882
± DIAGNOSTICSAIR CONDITIONING SYSTEM
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminals TR and SGTR of A/C amplifier connector.
PREPARATION:
(a) Remove center cluster module control with connectors
still connected.
(b) Turn the ignition switch ON.
CHECK:
Check voltage between terminals TR and SGTR of A/C amplifi-
er connector at each temperature.
OK:
at 25 °C (77 °F) : 1.8 ± 2.2 V
at 40 °C (104 °F) : 1.2 ± 1.6 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 11 is output, check and replace A/C amplifier.
2 Check room temperature sensor.
PREPARATION:
Remove room temperature sensor (See page AC±60).
CHECK:
Check resistance between terminals 1 and 2 of room tempera-
ture sensor connector at each temperature.
OK:
at 25 °C (77 °F) : 1.6 ± 1.8 kW
at 40 °C (104 °F) : 0.5 ± 1.7 kW
HINT:
As the temperature increases, the resistance decreases.
NG Replace room temperature sensor.
OK

± DIAGNOSTICSAIR CONDITIONING SYSTEM
DI±883
2001 PRIUS (RM778U)
3 Check harness and connector between A/C amplifier and room temperature sen-
sor (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace A/C amplifier.