Mazda MX-6 1998, Workshop Manual

Page: 946 / 1282

CONTROL SYSTEM
HEATER CONTROL UNIT INSPECTION
W 6 U 7 4 0 W 1 9
1. Slide out the heater control unit with the connectors still connected. (Refer to 07-40 HEATER CONTROL
UNIT REMOVAL/INSTALLATION.)
2. Measure the voltage at each heater control unit terminal and refer to the terminal voltage list.
3. Disconnect the heater control unit connector before checking for continuity at terminal 2B and 2J.
4. If not as specified, inspect the parts listed under “ Inspection area” and the related wiring harnesses.
5. If the parts and wiring harnesses are okay but the system still does not work properly, replace the heater
control unit.
Terminal Voltage List (Reference)
10 1M
1K 1E 1C
1A
1 p 1N
1L
1J
1H 1F
1D
1B
W 6 U 7 4 0 W A W
Terminal Signal Connection Test condition
Voltage (V)/
Continuity
Inspection area
1A
Common power
source Airflow mode
actuator
Moving to DEFROSTER
0.5
Airflow mode actuator
Moving to VENT 10.5
1B Panel light control
Panel light
control SW
c r 0 9 -1 8 PANEL LIGHT
CONTROL SWITCH,
Terminal Voltage List
(Reference), C terminal
inspection
—
Panel light control SW
1C
Common power
source
Airflow mode
actuator
Moving to VENT
0.5
Airflow mode actuator
Moving to DEFROSTER 10.5
1D TNS TNS relay
Headlight switch at TNS position B+
TNS relay
Headlight switch at OFF 0
1E Fan SW
• Fan SW
• Resistor
Fan SW
Off B+
• Fan SW
• Resistor
1 st position 0.1
2nd position 0.3
3rd position 0.5
4th position 0.4
1F A/C
Refrigerant
pressure SW
(LO)
Fan SW and A/C SW off B+
• Refrigerant
pressure SW (LO)
• Refrigerant
pressure SW (HI)
• ECM/PCM
Fan SW and A/C SW on 0
1H RECIRCULATE
Air intake
actuator
Air intake mode at RECIRCULATE 0
Air intake actuator
Air intake mode at FRESH B+
1J FRESH
Air intake
actuator
Air intake mode at FRESH
0
Air intake actuator
Air intake mode at RECIRCULATE B+
1K DEFROSTER
Airflow mode
actuator
Airflow mode at DEFROSTER 0
Airflow mode actuator
Other 10.6
1L HEAT/DEF
Airflow mode
actuator
Airflow mode at HEAT/DEF 0
Airflow mode actuator
Other
10.6
1M HEAT
Airflow mode
actuator
Airflow mode at HEAT 0
Airflow mode actuator
Other 10.6
1N
VENT
Airflow mode
actuator
Airflow mode at VENT 0
Airflow mode actuator
Other 10.6
1 0 BI-LEVEL
Airflow mode
actuator
Airflow mode at BI-LEVEL 0
Airflow mode actuator
Other 10.6
IP — Not used — — —
2A +5 V Air mix actuator
IG SW at ON 5
—
IG SW at LOCK or ACC 0
0 7 -4 0 -1 4