Inspection Procedure

CAUTION: Be careful when replacing any part in the system or changing the coolant because the coolant in the heat storage tank is hot even if the engine is cold.

HINT:

To check the coolant heat storage (CHS) system, the ECM may cause the water pump of the CHS system to operate 5 hours after the power switch has been turned OFF.
Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine condition when malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

INSPECT ECM (WBAD - E2 VOLTAGE)

Turn the power switch ON (IG).

Measure voltage between the terminals WBAD and E2 of the E4 and E7 ECM connectors.

Standard:

VOLTAGE SPECIFICATIONS

Water Valve	Voltage V
Valve position "A" (Preheat mode)	Approximately 2.5 V
Valve position "B" (Recovering mode)	Approximately 3.5 V
Valve position "C" (Normal Operation)	Approximately 4.5 V

Fig 1: Identifying E4 And E7 ECM Connectors Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

After the HV main system is turned OFF (READY to IG OFF condition), the valve position will be set to position A.

OK: CHECK FOR INTERMITTENT PROBLEMS (See CHECK FOR INTERMITTENT PROBLEMS )
NG: GO TO NEXT STEP

INSPECT WATER W/BRACKET VALVE ASSY

Disconnect the W5 water valve connector.
Measure resistance between terminals WSL 1 and WSL2 of the water valve connector.

Measure resistance between terminals WSAD and E2 of the water valve connector.

RESISTANCE:

RESISTANCE SPECIFICATIONS

Terminals	Condition	Resistance kΩ
1 - 2	Motor resistance	Approximately 0.04
5 - 6	Sensor resistance	0.2 to 5.7

NG: REPLACE WATER W/BRACKET VALVE ASSY
OK: GO TO NEXT STEP

Fig 2: Identifying W5 Water Valve Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CHECK HARNESS AND CONNECTOR (WATER VALVE - ECM)

Disconnect the W5 water valve connector.
Disconnect the E4 and E7 ECM connectors.

Check the resistance between the wire harness side connectors.

Standard (Check for open):

TESTER CONNECTION SPECIFIED CONDITION DESCRIPTION

Tester Connection	Specified Condition
Water valve (W5-5) - WBAD (E7-20)	Below 1Ω
Water valve (W5-4) - VC (E4-18)	Below 1Ω
Water valve (W5-6) - E2 (E4-28)	Below 1Ω

Fig 3: Identifying W5 Water Valve Connector Terminals

Standard (Check for short):

TESTER CONNECTION SPECIFIED CONDITION DESCRIPTION

Tester Connection	Specified Condition
Water valve (W5-5) or WBAD (E7-20) - Body ground	10 kΩ or higher

Reconnect the water valve connector.
Reconnect the ECM connectors.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: GO TO NEXT STEP
REPLACE ECM (See ECM (1NZ-FXE) )

Fig 4: Identifying E4 And E7 ECM Connectors Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002