2002 MAZDA 6 fuel

LOCATION INDEX
U–9
U
CONTROL SYSTEMA6E850001040202
.
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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)

BASIC SYSTEM, CONTROL SYSTEM
U–15
U
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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.
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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

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).
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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

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——

ON-BOARD DIAGNOSTIC
U–22–3
U
Simulation Test Item Table
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Diagnostic procedure
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FP
(Fuel pump)On/Off•Water heater unit is not operating: Off
•Water heater unit is operating: On——
WATER_PMP
(Water pump)On/Off•Water heater unit is not operating: Off
•Water heater unit is operating: On——
GLOW PLUG
(Glow plugs)On/Off•Water heater unit is not operating: Off
•Water heater unit is operating: On——
COMB_FAN
(Combustion air fan)On/Off•Water heater unit is not operating: Off
•Water heater unit is operating: On——
LOCKOUT
(Heater lockout)Lock/
Unlock•Water heater unit is not operating: Lock
•Water heater unit is operating: Unlock——
FS
(Flame sensor)On/Off•Water heater unit is not operating: Off
•Water heater unit is operating: On——
HEATER
(Heater status)Inactive/
Active•Water heater unit is not operating:
Inactive
•Water heater unit is operating: Active——
HEATER_SW
(Heater activation switch)Inactive/
Active•Water heater unit is not operating:
Inactive
•Water heater unit is operating: Active—— PID Name
(Definition)Unit/
ConditionCondition/Specification
(Reference)ActionWater
Heater Unit
terminal
Item Definition OperationWater Heater
Unit terminal
CLR_LOCKOUT Heater lockout mode clearing command On/——
FUEL_PRIMEFuel pump priming command
(The fuel pump is activated for 5 seconds.)On/——
DTC B1317 Input voltage high
DETECTION
CONDITION•Voltage detected at water heater unit terminals A is more than 16 V.
POSSIBLE
CAUSE•Short to power circuit between the generator and PCM
•Generator malfunction
•Battery malfunction
STEP INSPECTION ACTION
1INSPECT BATTERY VOLTAGE
•Measure the battery voltage.
•Is the voltage less than 16 V?Yes Go to the next step.
No Inspect the charging system.
2INSPECT WATER HEATER UNIT
•Clear the DTC.
•Perform the KOEO Self Test. (See U–22 KOEO
Self Test/Combustion Test.)
•Is the same DTC present?Yes Replace the water heater unit.
(See U–15 WATER HEATER UNIT REMOVAL/
INSTALLATION)
No Go to the next step.
3VERIFY AFTER REPAIR PROCEDURE
•Perform the after repair procedure. (See U–22–1
After Repair Procedure.)
•Are any DTCs present?Yes Go to the applicable DTC troubleshooting.
No Troubleshooting completed.
A C E
B
D F WATER HEATER UNIT CONNECTOR

U–24
ON-BOARD DIAGNOSTIC
DTC B2449, B2450A6E857001038206
Diagnostic procedure
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DTC B2451, B2452A6E857001038207
Diagnostic procedure
DTCB2449 Glow plug circuit short to ground
B2450 Glow plug circuit open
DETECTION
CONDITION•CPU detects malfunction in glow plug circuit
POSSIBLE
CAUSE•Water heater unit malfunction
STEP INSPECTION ACTION
1INSPECT WATER HEATER UNIT
•Replace the water heater unit. (See U–15
WATER HEATER UNIT REMOVAL/
INSTALLATION)
•Perform the combustion Test. (See U–22 KOEO
Self Test/Combustion Test.)
•Are any DTCs present?Yes Go to the applicable DTC troubleshooting.
No Troubleshooting completed.
DTCB2451 Fuel pump (water heater system) circuit short to ground
B2452 Fuel pump (water heater system) circuit open
DETECTION
CONDITION•CPU detects malfunction in fuel pump (water heater system) circuit
POSSIBLE
CAUSE•Fuel pump (water heater system) malfunction
•Water heater unit malfunction
•Short to ground between water heater unit terminal B and fuel pump (water heater system) terminal A
•Open circuit between water heater unit terminal B and fuel pump (water heater system) terminal A
•Open circuit between fuel pump (water heater system) terminal B and GND
A C E
B D F WATER HEATER UNIT CONNECTORFUEL PUMP
(WATER HEATER SYSTEM)
CONNECTOR
A
B
STEP INSPECTION ACTION
1INSPECT WIRING HARNESS BETWEEN
WATER HEATER UNIT AND FUEL PUMP
(WATER HEATER SYSTEM) FOR
CONTINUITY
•Start the engine.
•Is the voltage at fuel pump (water heater
system) connector terminal A approximately
12 V?Yes Go to the next step
No Repair the wiring harness.
2INSPECT FUEL PUMP (WATER HEATER
SYSTEM)
•Inspect the fuel pump (water heater system).
(See U–16 FUEL PUMP (WATER HEATER
SYSTEM) INSPECTION)
•Is the fuel pump (water heater system) okay?Yes Go to the next step
No Replace the fuel pump (water heater system).
(See U–15 WATER HEATER UNIT REMOVAL/
INSTALLATION)
3INSPECT WIRING HARNESS BETWEEN
FUEL PUMP (WATER HEATER SYSTEM) AND
GROUND FOR CONTINUITY
•Is there continuity between the fuel pump
(water heater system) connector terminal B
and ground?Yes Go to the next step
No Repair the wiring harness.

ON-BOARD DIAGNOSTIC
U–25
U
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DTC B2453, B2454A6E857001038208
Diagnostic procedure
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DTC B2548A6E857001038210
Diagnostic procedure
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4INSPECT WATER HEATER UNIT
•Clear the DTC.
•Perform the KOEO Self Test. (See U–22
KOEO Self Test/Combustion Test.)
•Is the same DTC present?Yes Replace the water heater unit.
(See U–15 WATER HEATER UNIT REMOVAL/
INSTALLATION)
No Go to the next step.
5VERIFY AFTER REPAIR PROCEDURE
•Perform after repair procedure. (See U–22–1
After Repair Procedure.)
•Are any DTCs present?Yes Go to the applicable DTC troubleshooting.
No Troubleshooting completed. STEP INSPECTION ACTION
DTCB2453 Blower fan circuit short to ground
B2454 Blower fan circuit open
DETECTION
CONDITION•CPU detects Malfunction in blower fan circuit
POSSIBLE
CAUSE•Water heater unit malfunction
ACTION
•Replace the water heater unit.
(See U–15 WATER HEATER UNIT REMOVAL/INSTALLATION)
DTC B2548 Water heater lockout mode
DETECTION
CONDITION•This DTC is stored if the water heater unit detects the same DTC three times and the water heater unit
then suspends system operation for safety reasons.
POSSIBLE
CAUSE•Water heater unit malfunction
•Fuel pump (water heater system) malfunction
•Generator malfunction
•Battery malfunction
•Open or short circuit in related harness
STEP INSPECTION ACTION
1INSPECT WATER HEATER UNIT
•Perform the lockout reset. (See U–22–1 Lockout
Reset.)
•Read DTCs using the SST (WDS or equivalent)
•Are any DTCs present?Yes Go to applicable DTC troubleshooting.
No Troubleshooting completed.

U–26
TROUBLESHOOTING
FOREWORDA6E858001038201•Confirm the symptom using the following troubleshooting index and carry out the appropriate action.
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TROUBLESHOOTING INDEXA6E858001038202
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TROUBLESHOOTING
No. TROUBLESHOOTING ITEM ACTION
1 Fuel odor•Inspect the water heater system in the vehicle fuel
system.
•Inspect the fuel line for leakage, kinks, or blockage.
•If normal, there is an internal water heater leak.
—Replace the water heater unit.
2 The heater does not achieve full load operation•Replace the water heater unit.
3 Continuous white smoke during combustion operation•Replace the water heater unit.
4 Loss of coolant (leakage). Heater develops smoke during
combustion operation; smell of exhaust fumes extremely
sweet•Inspect the coolant hose for leakage, kinks,
looseness, and loose hose clamps.
•If normal, there is an internal water heater leak.
—Replace the water heater unit.
5 Loss of fuel (leakage)•Inspect the water heater system integration in the
vehicle’s fuel system.
•Inspect the fuel line connections for leakage.
•If normal, there is an internal water heater leak.
—Replace the water heater unit.
6 The water heater unit does not communicate with the SST
(WDS or equivalent)•Refer to section T, ON-BOARD DIAGNOSTIC
[MULTIPLEX COMMUNICATION SYSTEM].