NO.1 WATER HEATER UNIT DOES NOT OPERATE [WATER HEATER SYSTEM]
id0703d1803200
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1
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Water heater unit does not operate
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DESCRIPTION
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• Water heater unit does not operate (no flame noise) even under operation conditions (ambient temperature is less than 5 °C {41 °F} and engine coolant temperature is less than 40 °C {104 °F}).
• Communication between M-MDS is disabled.
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POSSIBLE CAUSE
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• Malfunction in water heater unit power supply system
• Malfunction in water heater unit ground system
• Water heater unit cannot determine operation condition
• Water heater unit internal parts malfunction
• Fuel pump malfunction
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Diagnostic procedure
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STEP |
INSPECTION |
ACTION |
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1
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VERIFY DTCs
• Verify the water heater unit, PCM, BCM and instrument cluster DTCs using the M-MDS.
• Is the DTC displayed?
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Yes
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Perform the corresponding DTC inspection.
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No
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If no DTC is displayed:
• Go to Step 6.
If communication error is displayed:
• Go to the next step.
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2
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INSPECT FUSE
• Inspect the FOH 20 A fuse.
• Is the fuse broken or burnt out?
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Yes
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If the fuse is broken:
• Replace the fuse, then perform Step 1 again.
If the fuse is burnt out:
• Repair short to ground in wiring harness between the fuse and water heater unit terminal E, replace the fuse, then perform Step 1 again.
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No
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Go to the next step.
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3
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INSPECT WATER HEATER UNIT CONNECTOR CONDITION
• Inspect the connector condition of the water heater unit.
• Is the connector connected correctly?
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Yes
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Go to the next step.
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No
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Repair or replace the malfunctioning part, then perform Step 1 again.
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4
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INSPECT WATER HEATER UNIT POWER SUPPLY SYSTEM WIRING HARNESS FOR OPEN CIRCUIT
• Switch ignition to off.
• Disconnect the water heater unit connector.
• Switch ignition to ON.
• Inspect the voltage at water heater unit connector terminal E (wiring harness-side).
• Is the voltage B+?
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Yes
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Go to the next step.
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No
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Inspect for open circuit in wiring harness between battery positive terminal and water heater unit terminal 1E, and repair it.
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5
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INSPECT WATER HEATER UNIT GROUND SYSTEM
• Disconnect the water heater unit connector.
• Inspect the wiring harness for continuity between water heater unit connector terminal connector terminal C and body ground.
• Is there continuity?
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Yes
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Inspect and repair the following, then perform Step 1 again.
• Open or short circuit in wiring harness between water heater unit and DLC-2
• M-MDS cable connection to DLC-2
If communication error is displayed continuously, replace the water heater unit.
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No
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Inspect and repair the following, then perform Step 1 again.
• Ground point (looseness, disengagement, lifting)
• Open circuit in wiring harness between water heater unit vehicle-side connector terminal C and body ground
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6
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DETERMINE IF MALFUNCTION CAUSE IS WATER HEATER UNIT OR OPERATION CONDITION SIGNAL RELATED
• Perform “FFH Start Heater Utility” using M-MDS.
• Is the inspection result normal?
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Yes
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Go to the next step.
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No
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Go to Step 9.
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7
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INSPECT AMBIENT TEMPERATURE SIGNAL
• Measure the voltage at BCM terminal 1X.
• Is the voltage normal?
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Yes
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Go to the next step.
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No
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Inspect the ambient temperature sensor.
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8
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INSPECT ENGINE COOLANT TEMPERATURE AND ENGINE SPEED SIGNAL
• Monitor the PCM PID “RPM” and “ECT” using the M-MDS.
(See PCM INSPECTION [MZR-CD 2.2].)
• Does the monitor value correspond to the actual engine coolant temperature and engine speed?
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Yes
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Replace the water heater unit.
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No
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Inspect the ECT sensor.
Inspect the crankshaft position sensor.
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9
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INSPECT FUEL PUMP
• Inspect the fuel pump.
• Is the fuel pump normal?
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Yes
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Replace the water heater unit.
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No
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Replace the fuel pump.
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