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 7 °C {45 °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 1A

―  AUX HEATER 20 A fuse malfunction (break or burn-out)

•  Malfunction in water heater unit ground system

―  Open circuit in wiring harness between water heater unit terminal 1B 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)

―  Communication error between water heater unit and PCM (engine speed, engine coolant temperature)

•  Water heater unit internal parts malfunction

•  Fuel pump malfunction

Diagnostic procedure

STEP	INSPECTION		ACTION
1	VERIFY DTCs Verify the water heater unit DTCs using the M-MDS. • Is the DTC displayed?	Yes	Perform the corresponding DTC inspection. (See DTC TABLE [WATER HEATER SYSTEM].)
1		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 AUX HEATER 20 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 1A, replace the fuse, then perform Step 1 again.
2		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.
3		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 1A (wiring harness-side). • Is the voltage B+?	Yes	Go to the next step.
4		No	Inspect for open circuit in wiring harness between battery positive terminal and water heater unit terminal 1A, 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 1B 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.
5		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 1B and body ground
6	DETERMINE IF MALFUNCTION CAUSE IS WATER HEATER UNIT OR OPERATION CONDITION SIGNAL RELATED • Perform “FFH Operation Check” using M-MDS. (See WATER HEATER SYSTEM OPERATION CHECK [FULL-AUTO AIR CONDITIONER].) (See WATER HEATER SYSTEM OPERATION CHECK [MANUAL AIR CONDITIONER].) • Is the inspection result normal?	Yes	Go to the next step.
6		No	Go to Step 10.
7	VERIFY OPERATION CONDITION SIGNAL • Monitor the following water heater unit PIDs using the M-MDS. ― EX_TEMP (ambient temperature) ― ECT (engine coolant temperature) ― RPM (engine speed) • Does the monitor value correspond to the actual vehicle conditions?	Yes	Replace the water heater unit. (See WATER HEATER UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].) (See WATER HEATER UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)
7		No	If EX_TEMP (ambient temperature) does not correspond to the actual vehicle condition, go to the next step. If ECT (engine coolant temperature) does not correspond to the actual vehicle condition, go to Step 9. If RPM (engine speed) does not correspond to the actual vehicle condition, go to Step 9.
8	INSPECT AMBIENT TEMPERATURE SIGNAL • Monitor the instrument cluster PID “EX_TEMP” using M-MDS. (See PID/DATA MONITOR TABLE [INSTRUMENT CLUSTER].) • Does the monitor value correspond to the actual ambient temperature?	Yes	Replace the water heater unit. (See WATER HEATER UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].) (See WATER HEATER UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)
8		No	Inspect the ambient temperature sensor. (See AMBIENT TEMPERATURE SENSOR INSPECTION [FULL-AUTO AIR CONDITIONER].) (See AMBIENT TEMPERATURE SENSOR INSPECTION [MANUAL AIR CONDITIONER].)
9	INSPECT ENGINE COOLANT TEMPERATURE AND ENGINE SPEED SIGNAL • Monitor the PCM PID “RPM” and “ECT” using the M-MDS. (See PCM CONFIGURATION [MZR 1.8, MZR 2.0, MZR 2.5]) (See PCM CONFIGURATION [MZR-CD 2.2].) (See PCM CONFIGURATION [MZR 2.0 DISI].) (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].) (See WATER HEATER UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)
9		No	Inspect the ECT sensor. (See COOLANT RESERVE TANK REMOVAL/INSTALLATION [MZR 2.0 DISI].) (See COOLANT RESERVE TANK REMOVAL/INSTALLATION [MZR 1.8, MZR 2.0, MZR 2.5].) (See COOLANT RESERVE TANK REMOVAL/INSTALLATION [MZR-CD 2.2].) (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR-CD 2.2].) Inspect the crankshaft position sensor. (SeeCRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZR 1.8, MZR 2.0, MZR 2.5].) (See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZR-CD 2.2].) (See CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [MZR 2.0 DISI].) (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION [MZR-CD 2.2].)
10	INSPECT FUEL PUMP • Inspect the fuel pump. (See FUEL PUMP (WATER HEATER SYSTEM) INSPECTION [FULL-AUTO AIR CONDITIONER].) (See FUEL PUMP (WATER HEATER SYSTEM) INSPECTION [MANUAL AIR CONDITIONER].) • Is the fuel pump normal?	Yes	Replace the water heater unit. (See WATER HEATER UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].) (See WATER HEATER UNIT REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)
10		No	Replace the fuel pump. (See FUEL PUMP (WATER HEATER SYSTEM) REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].) (See FUEL PUMP (WATER HEATER SYSTEM) REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER].)