Page 839 of 909

T–28
WARNING AND INDICATOR SYSTEM
Fuel gauge sender cap removal note
1. Using the SST, remove the fuel gauge sender
cap.
Fuel Gauge Sender Cap Installation Note
1. Verify that the fuel tank mark is aligned with the
fuel gauge sender sub-unit mark as shown.
2. Using the SST, tighten the fuel gauge sender cap
without shifting the mark.
Tightening torque
80—90 N·m {8.2—9.1 kgf·m, 60—66 ft·lbf}
Fuel leak inspection after fuel gauge sender sub-unit installation
1. Drive the vehicle.
2. Perform a quick start and a hard brake 5—6 times.
3. Stop the vehicle.
4. Verify that there is no fuel leakage near the fuel pump unit in the vehicle interior.
End Of Sie
FUEL GAUGE SENDER UNIT INSPECTIONA6E8118609602021. Move the float to the topmost and bottommost positions, and verify that the resistance between terminals A and
B of the unit and the position of the float are as indicated in the figure.
•If they are not as indicated, replace the fuel gauge sender unit.
End Of Sie
49 T042 001A
A6J81182105
FUEL GAUGE
SENDER
SUB-UNIT MARK
MARK
A6E81182002
4WD
44.4—58.4
{1.75—2.29}
TOPMOST
POSITION
BOTTOMMOST
POSITION BASIC
POSITION
ARM
FULCRUM
72.9—86.9
{2.88—3.42}AB
*
53.9—60.9
{2.13—2.39}
TOPMOST
POSITION
BOTTOMMOST
POSITION BASIC
POSITION
ARM
FULCRUM
89.7—96.7
{3.54—3.80}
mm {in}
FUEL GAUGE SENDER UNIT
FUEL GAUGE SENDER SUB-UNIT
6.1—8.1 ohms
57.6—59.6 ohms7.2—9.2 ohms
66.5—68.5 ohms
A6E81181103
Page 864 of 909

U–1
U
UHEATER AND AIR CONDITIONER SYSTEMS
OUTLINE................................................................ U-2
OUTLINE OF CONSTRUCTION.......................... U-2
FEATURES .......................................................... U-2
SPECIFICATIONS ............................................... U-2
CONTROL SYSTEM............................................... U-6
WATER HEATER SYSTEM................................. U-6
OUTLINE................................................................ U-7
SUPPLEMENTAL SERVICE INFORMATION .....U-7
LOCATION INDEX.................................................U-8
BASIC SYSTEM................................................... U-8
CONTROL SYSTEM ............................................ U-9
BASIC SYSTEM................................................... U-10
A/C UNIT REMOVAL/INSTALLATION...............U-10
A/C COMPRESSOR
REMOVAL/INSTALLATION ............................U-11
CONDENSER REMOVAL/INSTALLATION ....... U-12
REFRIGERANT LINES
REMOVAL/INSTALLATION ............................U-13
CONTROL SYSTEM............................................. U-15
WATER HEATER UNIT
REMOVAL/INSTALLATION ............................U-15
FUEL PUMP (WATER HEATER SYSTEM)
INSPECTION .................................................. U-16
CLIMATE CONTROL UNIT INSPECTION.........U-16
ON-BOARD DIAGNOSTIC...................................U-22
FOREWORD ......................................................U-22
DTC TABLE ................................................... U-22-2
PID/DATA MONITOR AND RECORD ........... U-22-2
DTC B1317 .................................................... U-22-3
DTC B1318 ........................................................ U-23
DTC B1342, B2463, B2537, B2538, B2547 ....... U-23
DTC B2449, B2450 ............................................ U-24
DTC B2451, B2452 ............................................ U-24
DTC B2453, B2454 ............................................ U-25
DTC B2548 ........................................................ U-25
TROUBLESHOOTING.......................................... U-26
FOREWORD ......................................................U-26
TROUBLESHOOTING INDEX ...........................U-26 FEATURES
SERVICE
Page 869 of 909
U–6
CONTROL SYSTEM
WATER HEATER SYSTEMA6E854000169201Outline
•The function, structure and operation of the water heater system is essentially carried over from that of the
current MPV (LW) model, except for following:
—Full/half switching temperature has been changed.
Structural View
.
Operation
Full/half switching
•Depending on the engine coolant temperature, the CPU sets the flame to either full or half strength settings.
.
End Of Sie
CONTROL SYSTEM
1
2
A6E85402002
1 Water heater unit2 Fuel pump (water heater system)
3
1
2
68
{154}74
{165}75
{167}78
{172}˚C
{˚F}
A6E85402003
1 Full mode
2 Half mode3 Idle mode
Page 870 of 909
OUTLINE
U–7
U
SUPPLEMENTAL SERVICE INFORMATIONA6E850201038204•The following additions have been made for the MZR-CD (RF Turbo) since the publication of the Mazda6
Workshop Manual (1730-1*-02C).
A/C unit
•Removal/installation procedure has been modified.
A/C compressor
•Removal/installation procedure has been modified.
Condenser
•Removal/installation procedure has been modified.
Refrigerant lines
•Removal/installation procedure has been modified.
Water heater unit
•Removal/installation procedure has been added.
Fuel pump (water heater system)
•Inspection procedure has been added.
Climate control unit
•Inspection procedure has been modified.
Water heater system
•On-board diagnostic system has been added.
End Of Sie
OUTLINE
Page 872 of 909
LOCATION INDEX
U–9
U
CONTROL SYSTEMA6E850001040202
.
End Of Sie
1
2
3
A6E85002003
1 Water heater unit
(See U–15 WATER HEATER UNIT REMOVAL/
INSTALLATION)
2 Fuel pump (water heater system)
(See U–16 FUEL PUMP (WATER HEATER
SYSTEM) INSPECTION)3 Climate control unit
(See U–16 CLIMATE CONTROL UNIT
INSPECTION)
Page 878 of 909

BASIC SYSTEM, CONTROL SYSTEM
U–15
U
End Of Sie
WATER HEATER UNIT REMOVAL/INSTALLATIONA6E854000170201
Caution
•If the negative battery cable is disconnected during the purge cycle of the water heater unit, the
gas in the unit may not be properly scavenged, causing white smoke (unburnt gas) to emit from
the exhaust pipe. Before disconnecting the negative battery cable, verify that the water heater unit
is not operating (no blower fan operation noise).
1. Complete the “BEFORE REPAIR PROCEDURE”. (See F2–45 BEFORE REPAIR PROCEDURE.)
2. Disconnect the negative battery cable.
3. Drain the engine coolant.
4. Remove the fuel filter with the pipes still connected, and fix the fuel filter using a rope so that it is out of the way.
5. Remove in the order indicated in the table.
6. Install in the reverse order of removal.
7. Complete the “AFTER REPAIR PROCEDURE”. (See F2–45 AFTER REPAIR PROCEDURE.)
8. Refill the engine coolant.
.
End Of Sie
1 Cooler pipe No.1
2 Cooler pipe No.2
3 Cooler pipe No.3
4 Cooler pipe No.45 Cooler pipe No.5 (R.H.D. only)
6 Cooler hose (HI)
7 Cooler hose (LO)
CONTROL SYSTEM
A
A
B
B
5
4
3
1
2
6
TO
FUEL PIPE
8.9—12.7
{90—130, 79—112}
N·m {kgf·cm, in·lbf}
8.9—12.7
{90—130, 79—112}
A6E85402004
1 Connector
2 Heater hose No.1
3 Heater hose No.34 Water heater unit
5 Fuel pump (water heater system)
6 Exhaust pipe
Page 879 of 909

U–16
CONTROL SYSTEM
FUEL PUMP (WATER HEATER SYSTEM) INSPECTIONA6E8540133502011. Inspect for continuity between fuel pump terminal
A and B using an ohmmeter.
•If not as specified, replace the fuel pump
(water heater system).
End Of Sie
CLIMATE CONTROL UNIT INSPECTIONA6E854061190201Full-auto Air Conditioner
1. Connect the all center panel connectors.
2. Turn the ignition switch to ON position.
3. Measure the voltage at each climate control unit terminal and refer to the terminal voltage list.
•If not as specified, inspect the parts listed under “Action” and the related wiring harness.
—If there is any malfunction, replace the climate control unit.
Terminal Voltage List (Reference)
AME8540W007
Terminal Signal Connected to Test condition Voltage (V) Action
1A Blower motor
feedback signal•Blower motor
•Power MOS
FETFan switch is OFF 12 1. Inspect for continuity or
short circuit (Climate control
unit—blower motor: 1A—B)
(Climate control unit—power
MOS FET: 1A—B, 1C—E)
(Blower motor—blower
relay: A—C) (Blower relay—
fuse: D—BLOWER 40 A
fuse)
2. Inspect for continuity (Power
MOS FET—ground: A—
GND) (Blower relay—
ground: A—GND)
3. Inspect power MOS FET
4. Inspect blower motor
5. Inspect blower relay
6. Inspect BLOWER 40 A fuse
7. Replace power MOS FET Fan switch is at manual
LO7.8
Fan switch is at manual
HI
0.2
2A
1W
2B 2C
2D 2E
2F 2G
2H 2I 2K
2L
* 1A
1B
* *
* *
* 1X1C 1E
1F * 1I
1K
1M 1O
1P 1Q 1S
1T 1U
1J 1L
A6E85402001
Page 887 of 909

U–22–2
ON-BOARD DIAGNOSTIC
PID/Data Monitor and Record Procedure
1. Connect SST (WDS or equivalent) to the vehicle
DLC-2 16-pin connector located as shown in the
figure.
2. Access and monitor PIDs by WDS or equivalent.
End Of SieDTC TABLEA6E857001038202
* : If a DTC not listed above is detected, there is a water heater malfunction, and the water heater must be
replaced.
End Of SiePID/DATA MONITOR AND RECORDA6E857001038209PID Monitoring Item Table
DLC-2
A6E3970W002
DTC Possible cause Page
B1317 Input voltage high (See U–22–3 DTC B1317)
B1318 Input voltage low (See U–23 DTC B1318)
B1342 Malfunction in water heater unit(See U–23 DTC B1342, B2463,
B2537, B2538, B2547)
B2449 Glow plug circuit short to ground (See U–24 DTC B2449, B2450)
B2450 Glow plug circuit open (See U–24 DTC B2449, B2450)
B2451 Fuel pump circuit short to ground (See U–24 DTC B2451, B2452)
B2452 Fuel pump circuit open (See U–24 DTC B2451, B2452)
B2453 Blower fan circuit short to ground (See U–25 DTC B2453, B2454)
B2454 Blower fan circuit open (See U–25 DTC B2453, B2454)
B2463 Overheat(See U–23 DTC B1342, B2463,
B2537, B2538, B2547)
B2537 Water heater system does not start(See U–23 DTC B1342, B2463,
B2537, B2538, B2547)
B2538 Unstable flame(See U–23 DTC B1342, B2463,
B2537, B2538, B2547)
B2547 Flame prior to operation(See U–23 DTC B1342, B2463,
B2537, B2538, B2547)
B2548 Water heater lockout mode (See U–25 DTC B2548)
PID Name
(Definition)Unit/
ConditionCondition/Specification
(Reference)ActionWater
Heater Unit
terminal
CCNTFFH
(Number of continuous
codes)—•DTC is detected: 1—255
•DTC is not detected: 0Perform inspection
using appropriate
DTC.—
ECT
(Engine coolant temperature)°C°F•ECT 20 °C {68 °F}: 20 °C {68 °F}
•ECT 60 °C {140 °F}: 60 °C {140 °F}——
VPWR_FFH
(Module supply voltage)V•Ignition switch ON: B+Inspect water heater
unit power supply
terminal.A
VPWR_LMT
(Low voltage threshold)V•Ignition switch ON: approx. 9.5 VInspect water heater
unit power supply
terminal.A
FAN
(Fan control)%•Blower fan is not operating: 0 %
•Blower fan is operating: 0—100 %——
GPD
(Glow plug duty cycle)%•Water heater unit is not operating: 0 %
•Water heater unit is operating: 0—100 %——
BLOWRMTR
(Blower motor)On/Off•Blower fan is not operating: Off
•Blower fan is operating: On——