P2601
1NZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2601: Coolant Pump Control Circuit Range / Performance
DTC P2601 - Coolant Pump Control Circuit Range / Performance
DESCRIPTION
The coolant heat storage system uses an electric pump to supply hot coolant stored in the CHS tank into the cylinder head of the engine, in order to optimize engine starting combustion and reduce the amount of unburned gas that is discharged while the engine is started. Before the engine starts, the ECM operates the electric water pump to direct the hot coolant in the CHS tank into the engine, in order to heat the cylinder head (this process is called "preheat mode"). This system consists of the CHS tank, CHS water pump, CHS tank outlet temperature sensor, water valve, and a soak timer that is built in the ECM.
MONITOR DESCRIPTION
The ECM detects a malfunction in the coolant heat storage (CHS) system with the CHS tank coolant temperature, the position of the water valve, the running condition of the engine and the operating condition of the soak timer.
The soak timer built in the ECM prompts the ECM to actuate the water pump 5 hours after the HV system has been turned OFF by using the power switch. The ECM then checks the HV main system based on variations in the CHS tank outlet temperature (soak mode).
In order to ensure the reliable malfunction detection, the ECM detects the CHS water pump malfunction DTC in two ways. Thus, when the following two detection conditions are consecutively met, the ECM determines that there is malfunction in the water pump circuit and sets the DTC.
(1) Difference in the CHS tank outlet temperature and the engine coolant temperature before and after starting preheating at engine start (system start) is below 2°C (35.6°F).
(2) Variation in the CHS tank outlet temperature during soak mode is within 1°C (33.8°F) of its temperature before the CHS water pump was ON.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
Case 1:
Case 2:
TYPICAL MALFUNCTION THRESHOLDS
Case 1:
Case 2:
WIRING DIAGRAM
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 Techstream. 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 Freeze Frame Data.
PROCEDURE
1. CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P2601)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Turn the tester ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
(e) Read the DTCs.
Result:
HINT: If any other codes besides P2601 are output, perform troubleshooting for those DTCs first.
B -- GO TO DTC CHART
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (OPERATE WATER PUMP)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Turn the tester ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Water Pump.
(e) Check that the CHS W/P relay operates and the operating sounds of the water pump occurs.
Result:
NG -- INSPECT COOLANT HEAT STORAGE WATER PUMP RELAY (CHS WATER PUMP RELAY)
OK -- Continue to next step.
3. INSPECT OIL TEMPERATURE SENSOR (CHS TANK OUTLET TEMPERATURE SENSOR)
(a) Remove the coolant heat storage (CHS) tank outlet temperature sensor.
(b) Measure the resistance between the terminals.
Standard resistance:
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.
(c) Reinstall the coolant heat storage tank outlet temperature sensor.
NG -- REPLACE OIL TEMPERATURE SENSOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (ECM - CHS TANK OUTLET TEMPERATURE SENSOR)
(a) Check the harness and the connectors between the CHS tank outlet temperature sensor connector and the ECM connector.
(1) Disconnect the C19 CHS tank outlet temperature sensor connector.
(2) Disconnect the E4 and E7 ECM connectors.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open)::
Standard resistance (Check for short)::
(4) Reconnect the CHS tank outlet temperature sensor connector.
(5) Reconnect the ECM connectors.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
5. INSPECT COOLANT HEAT STORAGE WATER PUMP RELAY (CHS WATER PUMP RELAY)
(a) Remove the CHS W/P relay from the engine room relay block No. 2.
(b) Inspect the CHS W/P relay.
Standard resistance:
(c) Reinstall the CHS W/P relay.
NG -- REPLACE COOLANT HEAT STORAGE WATER PUMP RELAY
OK -- Continue to next step.
6. INSPECT WATER W/MOTOR & BRACKET PUMP ASSEMBLY
(a) Disconnect the C20 CHS water pump connector.
(b) Measure the resistance between the terminals of the water pump.
Standard resistance:
(c) Reconnect the CHS water pump connector.
NG -- REPLACE WATER W/MOTOR & BRACKET PUMP ASSEMBLY
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (CHS W/P RELAY - WATER PUMP AND ECM, WATER PUMP - GROUND)
(a) Check the harness and the connectors between the CHS water pump connector and the ECM connector.
(1) Remove the CHS W/P relay from the engine room relay block No. 2.
(2) Disconnect the E7 ECM connector.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
(4) Reinstall the integration relay.
(5) Reconnect the ECM connector.
(b) Check the harness and the connectors between the CHS water pump connector and the CHS W/P relay.
(1) Disconnect the CHS water pump connector.
(2) Remove the CHS W/P relay from the engine room relay block No. 2.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
(4) Reconnect the CHS water pump connector.
(5) Reinstall the integration relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM