A/C AMPLIFIER INSPECTION [FULL-AUTO AIR CONDITIONER]


BHE074061190W03

1. Turn the ignition switch to the ON position.

2. Connect the negative (-) lead of the tester to body ground.

3. By inserting the positive (+) lead of the tester into each A/C amplifier terminal, measure the voltage according to the terminal voltage table.

• If there is any malfunction, inspect the parts under "Inspection item(s)".
– If the parts under "Inspection item(s)" are found to be normal (except for terminal 1A), replace the A/C amplifier.
– For terminal 1A, first try replacing the power transistor. If there is still any malfunction, replace the A/C amplifier.

Terminal Voltage Table (Reference)

Terminal

Signal name

Connected to

Measurement condition

Voltage (V)

Inspection item(s)

1A
Blower fan speed control
Power transistor
Fan stopped
1.0 or less
• A/C amplifier: terminal voltage (1A)
Fan: manual LO
2.1
Fan: manual HI
2.9
1B
Blower motor feedback
• Blower motor
• Power transistor
Fan stopped
B+
1. Wiring harness: continuity, short circuit (A/C amplifier-power transistor: 1A-D, 1B-C) (Blower motor-blower relay: A-D) (Blower relay-fuse: C-HEATER 40 A, A-A/C 7.5 A)
2. Wiring harness: continuity (Power transistor-body ground: A-GND) (Blower relay-A/C amplifier: E-1L)
3. Power transistor
4. Blower motor
5. Blower relay
6. A/C 7.5 A fuse
7. HEATER 40 A fuse
8. Power transistor replacement
Fan: manual LO
9.0
Fan: manual HI
0.7
1C
Version signal (U.K. specs.)
Body ground
Under any condition
1.0 or less
• Wiring harness: continuity (A/C amplifier-GND: 1C-GND)
1D
Version signal (European (L.H.D.) specs.)
Body ground
Under any condition
1.0 or less
• Wiring harness: continuity (A/C amplifier-GND: 1D-GND)
1E
-
-
-
-
-
1F
-
-
-
-
-
1G
-
-
-
-
-
1H
-
-
-
-
-
1I
Motor operation
Air intake actuator
Switched to RECIRCULATE
1.0 or less
• Wiring harness: continuity, short circuit (A/C amplifier-air intake actuator: 1I-A, 1J-C)
• Air intake actuator
Switched to FRESH
12
1J
Motor operation
Air intake actuator
Switched to RECIRCULATE
12
• Wiring harness: continuity, short circuit (A/C amplifier-air intake actuator: 1J-C, 1I-A)
• Air intake actuator
Switched to FRESH
1.0 or less
1K
Rear window defroster operation
Rear window defroster relay
Rear window defroster switch OFF
B+
• Wiring harness: continuity, short circuit (A/C amplifier-rear window defroster relay: 1K-E)
• Rear window defroster relay
Rear window defroster switch ON
1.0 or less
• A/C amplifier: terminal voltage (2C, 2N)
1L
Blower motor operation
Blower relay
Fan switch OFF
B+
• Wiring harness: continuity, short circuit (A/C amplifier-blower relay: 1L-E)
• Blower relay
Fan switch ON
1.0 or less
• A/C amplifier: terminal voltage (2C, 2N)
1M
A/C
Refrigerant pressure switch
Fan stopped
B+
• Wiring harness: continuity, short circuit (A/C amplifier-refrigerant pressure switch: 1M-B) (Refrigerant pressure switch-PCM: C-4W)
• Refrigerant pressure switch
• PCM: terminal voltage (4W)
Fan switch: ON and A/C switch: ON
1.0 or less
• A/C amplifier: terminal voltage (2C, 2N)
1N
-
-
-
-
-
1O
-
-
-
-
-
1P
Signal
-
-
-
-
1Q
-
-
-
-
-
1R
Signal
-
-
-
-
1S
-
-
-
-
-
1T
-
-
-
-
-
1U
Motor operation
Air mix actuator
Moving towards COLD
1.0 or less
• Wiring harness: continuity, short circuit (A/C amplifier-air mix actuator: 1U-F (L.H.D.) G (R.H.D.), 1V-G (L.H.D.) F (R.H.D.))
• Air mix actuator
Moving towards HOT
12
1V
Motor operation
Air mix actuator
Moving towards COLD
12
• Wiring harness: continuity, short circuit (A/C amplifier-air mix actuator: 1U-F (L.H.D.) G (R.H.D.), 1V-G (L.H.D.) F (R.H.D.))
• Air mix actuator
Moving towards HOT
1.0 or less
1W
Motor operation
Airflow mode actuator
Switched to DEFROSTER
12
• Wiring harness: continuity, short circuit (A/C amplifier-airflow mode actuator: 1W-G, 1X-F)
• Airflow mode actuator
Switched to VENT
1.0 or less
1X
Motor operation
Airflow mode actuator
Switched to DEFROSTER
1.0 or less
• Wiring harness: continuity, short circuit (A/C amplifier-airflow mode actuator: 1W-G, 1X-F)
• Airflow mode actuator
Switched to VENT
12
2A
B+
ROOM 15 A fuse
Under any condition
B+
• Wiring harness: continuity, short circuit (A/C amplifier- fuse: 2F-ROOM 15 A)
• ROOM 15 A fuse
2B
-
-
-
-
-
2C
IG2
A/C 7.5 A fuse
IG SW ON
B+
• Wiring harness: continuity, short circuit (A/C amplifier- fuse: 2C-A/C 7.5 A)
• A/C 7.5 A fuse
IG SW LOCK
1.0 or less
• Wiring harness: continuity, short circuit (A/C amplifier- fuse: 2C-A/C 7.5 A)
2D
-
-
-
-
-
2E
-
-
-
-
-
2F
-
-
-
-
-
2G
Potentiometer input
Airflow mode actuator
VENT
4.0
• Wiring harness: continuity, short circuit (A/C amplifier-airflow mode actuator: 2G-E, 2P-C)
• Airflow mode actuator
• A/C amplifier: terminal voltage (2O)
BILEVEL
3.3
HEAT
2.6
HEAT/DEF
1.8
DEFROSTER
1.0
2H
Potentiometer input
Air mix actuator
Set temperature at MAX COLD
3.9
• Wiring harness: continuity, short circuit (A/C amplifier-air mix actuator: 2H-E, 2P-A (L.H.D.) C (R.H.D.))
• Air mix actuator
• A/C amplifier: terminal voltage (2O)
Set temperature at MAX HOT
1.1
2I
Solar radiation sensor input
Solar radiation sensor
Incandescent light (approx. 60 W) shined directly on the solar radiation sensor from a distance of approx. 100 mm {3.9 in}
4.0
• Wiring harness: continuity (A/C amplifier-solar radiation sensor: 2I-B, 2O-A)
• A/C amplifier: terminal voltage (2O)
• Solar radiation sensor
Blocking light to solar radiation sensor
1.0 or less
2J
Evaporator temperature sensor input
Evaporator temperature sensor
Compared with temperature detected by evaporator temperature sensor
Refer to graph 1
• Wiring harness: continuity (A/C amplifier-evaporator temperature sensor: 2J-B, 2P-A)
• Wiring harness: short circuit (A/C amplifier-evaporator temperature sensor: 2J-B)
• Evaporator temperature sensor
• A/C amplifier: terminal voltage (2C, 2N)
2K
Ambient temperature sensor input
Ambient temperature sensor
Compared with temperature detected by ambient temperature sensor
Refer to graph 2
• Wiring harness: continuity (A/C amplifier-ambient temperature sensor: 2K-B, 2P-A)
• Wiring harness: short circuit (A/C amplifier-ambient temperature sensor: 2K-B)
• Ambient temperature sensor
• A/C amplifier: terminal voltage (2C, 2N)
2 L
Cabin temperature sensor input
Cabin temperature sensor
Compared with temperature detected by cabin temperature sensor
Refer to graph 3
• Wiring harness: continuity (A/C amplifier-cabin temperature sensor: 2L-B, 2P-A)
• Wiring harness: short circuit (A/C amplifier-cabin temperature sensor: 2L-B)
• Cabin temperature sensor
• A/C amplifier: terminal voltage (2C, 2N)
2M
ECT sensor input
PCM
Compared with temperature detected by ECT sensor
Refer to graph 4
• Wiring harness: continuity, short circuit (A/C amplifier-PCM: 2M-5W)
• ECT sensor
• A/C amplifier: terminal voltage (2C, 2N)
2N
GND
Body ground
Under any condition
1.0 or less
• Wiring harness: continuity (A/C amplifier-GND: 2N-GND)
2O
+5 V
• Air mix actuator
• Airflow mode actuator
• Solar radiation sensor
IG SW ON
5.0
• Wiring harness: short circuit (A/C amplifier-air mix actuator, airflow mode actuator, solar radiation sensor: 2O-C (L.H.D.) A (R.H.D.), A, A)
• Air mix actuator
• Airflow mode actuator
• Solar radiation sensor
• A/C amplifier: terminal voltage (2C, 2N)
IG SW LOCK
1.0 or less
• A/C amplifier replacement
2P
Sensor GND
• Ambient temperature sensor
• Cabin temperature sensor
• Evaporator temperature sensor
• Air mix actuator
• Airflow mode actuator
Under any condition
1.0 or less
• A/C amplifier: terminal voltage (2N)