NO.1 WATER HEATER UNIT DOES NOT OPERATE [WATER HEATER SYSTEM]SM2445632
NO.1 WATER HEATER UNIT DOES NOT OPERATE [WATER HEATER SYSTEM]

id0703d1803200

1
Water heater unit does not operate
DESCRIPTION
• 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 60 °C {140 °F}).
• Communication between M-MDS is disabled.
POSSIBLE CAUSE
• Malfunction in water heater unit power supply system
― Open circuit, or short to ground in wiring harness between battery positive terminal and water heater unit terminal E
― W.HEATER 30 A fuse malfunction (break or burn-out)
• Malfunction in water heater unit ground system
― Open circuit in wiring harness between water heater unit terminal C and body ground
― Ground point lifting or loosening
• Water heater unit cannot determine operation condition
― Communication error between water heater unit and instrument cluster (ambient temperature, engine speed, engine coolant temperature)
― Communication error between instrument cluster and PCM (engine speed, engine coolant temperature)
― Communication error between instrument cluster and climate control unit
• Water heater unit internal parts malfunction
• Fuel pump malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY DTCs
Verify the water heater unit, PCM, climate control unit and instrument cluster DTCs using the M-MDS.
• Is the DTC displayed?
Yes
Perform the corresponding DTC inspection.
(See DTC TABLE [WATER HEATER SYSTEM].)
No
If no DTC is displayed:
• Go to Step 6.
If communication error is displayed:
• Go to the next step.
2
INSPECT FUSE
• Inspect the W.HEATER 30 A fuse.
• Is the fuse broken or burnt out?
Yes
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.
No
Go to the next step.
3
INSPECT WATER HEATER UNIT CONNECTOR CONDITION
• Inspect the connector condition of the water heater unit.
• Is the connector connected correctly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part, then perform Step 1 again.
4
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+?
Yes
Go to the next step.
No
Inspect for open circuit in wiring harness between battery positive terminal and water heater unit terminal 1E, and repair it.
5
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?
Yes
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.
No
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
6
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?
Yes
Go to the next step.
No
Go to Step 9.
7
INSPECT AMBIENT TEMPERATURE SIGNAL
• Measure the voltage at climate control unit terminal 1L.
• Is the voltage normal? (See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
Yes
Go to the next step.
No
Inspect the ambient temperature sensor.
(See AMBIENT TEMPERATURE SENSOR INSPECTION [FULL-AUTO AIR CONDITIONER].)
8
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?
Yes
Replace the water heater unit.
(See WATER HEATER UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
No
Inspect the ECT sensor.
(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR-CD 2.2].)
Inspect the crankshaft position sensor.
(See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [MZR-CD 2.2].)
9
INSPECT FUEL PUMP
• Inspect the fuel pump. (See FUEL PUMP (WATER HEATER SYSTEM) INSPECTION [FULL-AUTO AIR CONDITIONER].)
• Is the fuel pump normal?
Yes
Replace the water heater unit.
(See WATER HEATER UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
No
Replace the fuel pump.
(See FUEL PUMP (WATER HEATER SYSTEM) REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)