Inspection Procedure

CAUTION: Be careful when replacing any part in the CHS system or changing the coolant because the coolant in the CHS tank is hot even if the engine and the radiator are cold.

NOTE: If air bleeding is not performed completely, this DTC may be detected after changing the coolant.

HINT:

CHS stands for Coolant Heat Storage.
Although the DTC title says "Coolant Pump", this DTC is related to the CHS water pump.
The detection of this DTC indicates a malfunction in both the CHS water pump and the CHS W/P relay. Therefore, make sure to also check the relay when this DTC is output.
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 intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P2601)

Connect the intelligent tester to the DLC3.
Turn the power switch ON (IG).
Turn the tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

Read the DTCs.

Result

DTC CHART

Display (DTC Output)	Proceed to
P2601	A
P2601 and other DTCs	B

HINT:

If any other codes besides P2601 are output, perform troubleshooting for those DTCs first.

B: Go to DTC CHART

A: Go to Next Step

PERFORM ACTIVE TEST BY INTELLIGENT TESTER (OPERATE WATER PUMP)

Connect the intelligent tester to the DLC3.
Turn the power switch ON (IG).
Turn the tester ON.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / WATER PUMP.

Check that the CHS W/P relay operates and the operating sounds of the water pump occurs.

Result

TESTER CONNECTION SPECIFIED CONDITION

Tester operation	Specified Condition
WATER PUMP ON	CHS W/P relay and water pump operates

NG: Go to step 5

OK: Go to Next Step

INSPECT TEMPERATURE SENSOR (CHS TANK OUTLET TEMPERATURE SENSOR)

Remove the coolant heat storage (CHS) tank outlet temperature sensor.

Measure the resistance between the terminals.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
1 - 2	2 to 3 kΩ at 20°C (68°F)
1 - 2	0.2 to 0.4 kΩ at 80°C (176°F)

NOTE: In case of checking the CHS tank outlet temperature sensor in water, be careful not to allow water to contact the terminals. After checking, dry the sensor.

HINT:

Alternative procedure: Connect an ohmmeter to the installed CHS tank outlet temperature sensor and read the resistance. Use an infrared thermometer to measure the CHS tank outlet temperature in the immediate vicinity of the sensor. Compare these values to the resistance/ temperature graph. Change the engine temperature (warm up or allow to cool down) and repeat the test.

Reinstall the coolant heat storage tank outlet temperature sensor.

NG: REPLACE TEMPERATURE SENSOR

Fig 1: Measuring Resistance Between Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to Next Step

CHECK HARNESS AND CONNECTOR (ECM - CHS TANK OUTLET TEMPERATURE SENSOR)

Check the harness and the connectors between the CHS tank outlet temperature sensor connector and the ECM connector.

Disconnect the C19 CHS tank outlet temperature sensor connector.

Fig 2: Identifying C19 CHS Tank Outlet Temperature Sensor Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the E4 and E7 ECM connectors.

Measure the resistance according to the value(s) in the table below.

Standard resistance (Check for open):

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
C19-2 (CHS tank outlet temperature sensor) - E7-33 (THW2)	Below 1 Ω
C19-1 (CHS tank outlet temperature sensor) - E4-28 (E2)	Below 1 Ω

Fig 3: Disconnecting E4 And E7 ECM Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard resistance (Check for short):

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
C19-2 (CHS tank outlet temperature sensor) or E7-33 (THW2) - Body ground	10 kΩ or higher

Reconnect the CHS tank outlet temperature sensor connector.
Reconnect the ECM connectors.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE ECM

INSPECT COOLANT HEAT STORAGE WATER PUMP RELAY (CHS WATER PUMP RELAY)

Remove the CHS W/P relay from the engine room No. 2 relay block.

Inspect the CHS W/P relay.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
3-5	Below 1 Ω
3-5	10 kΩ or higher (Apply battery voltage to terminals 1 and 2)

Reinstall the CHS W/P relay.

NG: REPLACE COOLANT HEAT STORAGE WATER PUMP RELAY

Fig 4: Inspecting EFI Relay

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: Go to Next Step

INSPECT WATER W/MOTOR & BRACKET PUMP ASSEMBLY

Disconnect the C20 CHS water pump connector.

Measure the resistance between the terminals of the water pump.

Standard resistance

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
1 - 2	0.3 to 100 Ω

Reconnect the CHS water pump connector.

NG: REPLACE WATER W/MOTOR & BRACKET PUMP ASSEMBLY

Fig 5: Identifying C20 CHS Water Pump Connector (Connector Side)

OK: Go to Next Step

CHECK HARNESS AND CONNECTOR (CHS W/P RELAY - WATER PUMP AND ECM, WATER PUMP - GROUND)

Check the harness and the connectors between the CHS water pump connector and the ECM connector.

Remove the CHS W/P relay from the engine room No. 2 relay block.

Fig 6: Identifying C20 CHS Water Pump Connector (Wire Harness Side)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Disconnect the E7 ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard resistance (Check for open)

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
E7-15 (WPL) - 2 (CHS W/P relay)	Below 1 Ω

Standard resistance (Check for short)

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
2 (CHS W/P relay) or E7-15 (WPL) -Body ground	10 kΩ or higher

Reinstall the integration relay.
Reconnect the ECM connector.

Fig 7: Disconnecting E7 ECM Connector Terminal
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Check the harness and the connectors between the CHS water pump connector and the CHS W/P relay.

Disconnect the CHS water pump connector.
Remove the CHS W/P relay from the engine room relay block No. 2.

Measure the resistance according to the value(s) in the table below.

Standard resistance (Check for open)

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
2 (CHS water pump) - 5 (CHS W/P relay)	Below 1 Ω
1 (CHS water pump) - Body ground	Below 1 Ω

Fig 8: Identifying Engine Room No.2 Relay Block

Standard resistance (Check for short)

TESTER CONNECTION SPECIFIED CONDITION

Tester Connection	Specified Condition
2 (CHS water pump) or 5 (CHS W/P relay) - Body ground	10 kΩ or higher

Reconnect the CHS water pump connector.
Reinstall the integration relay.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: REPLACE ECM