Lexus ES: Engine Coolant Pump No Signal (P26CA31)
DESCRIPTION
Refer to DTC P26CA12.
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| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory | Note |
|---|---|---|---|---|---|---|
| P26CA31 | Engine Coolant Pump No Signal | The speed of the water inlet housing with water pump sub-assembly calculated from the WPI signal is less than 10 rpm (open or short in the WPI circuit) (1 trip detection logic). |
| Comes on | DTC stored | SAE Code: P26CA |
| DTC No. | Data List |
|---|---|
| P26CA31 |
|
MONITOR DESCRIPTION
The ECM receives a frequency signal (WPI) from the water inlet housing with water pump sub-assembly and calculates the speed of the water inlet housing with water pump sub-assembly. As the frequency signal (WPI) is 4 Hz when the water inlet housing with water pump sub-assembly is stopped to enable the ECM to detect an open or short in the signal line, the water inlet housing with water pump sub-assembly speed will be displayed as approximately 160 rpm even when the pump is stopped. If the water inlet housing with water pump sub-assembly speed is calculated to be less than 10 rpm, the ECM judges that there is an open or short in the WPI circuit and stores this DTC.
MONITOR STRATEGY
| Related DTCs | P26CA: Engine water pump circuit verify pulse input |
| Required Sensors/Components (Main) | Water inlet housing with water pump sub-assembly |
| Required Sensors/Components (Related) | - |
| Frequency of Operation | Continuous |
| Duration | 15 seconds |
| MIL Operation | Immediate |
| Sequence of Operation | None |
TYPICAL ENABLING CONDITIONS
| Monitor runs whenever the following DTCs are not stored | None |
| All of the following conditions are met | - |
| Auxiliary battery voltage | 8 V or higher |
| Power switch | On (IG) |
| Time after power switch off to on (IG) | 0.5 seconds or more |
TYPICAL MALFUNCTION THRESHOLDS
| Engine water pump speed | Less than 10 rpm |
CONFIRMATION DRIVING PATTERN
HINT:
-
After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.
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-
When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.
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- Connect the Techstream to the DLC3.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
- Turn the power switch off and wait for at least 30 seconds.
- Turn the power switch on (IG) [A].
- Turn the Techstream on.
-
Put the engine in Inspection Mode (Maintenance Mode).
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- Start the engine and maintain the engine speed at 2500 rpm or more for at least 40 seconds [B].
- Enter the following menus: Powertrain / Engine / Trouble Codes [C].
-
Read the pending DTCs.
HINT:
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine / Utility / All Readiness.
- Input the DTC: P26CA31.
-
Check the DTC judgment result.
Techstream Display
Description
NORMAL
- DTC judgment completed
- System normal
ABNORMAL
- DTC judgment completed
- System abnormal
INCOMPLETE
- DTC judgment not completed
- Perform driving pattern after confirming DTC enabling conditions
HINT:
- If the judgment result is NORMAL, the system is normal.
- If the judgment result is ABNORMAL, the system has a malfunction.
- If the judgment result is INCOMPLETE, perform steps [B] through [C] again.
-
[A] to [C]: Normal judgment procedure.
The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.
- When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.
WIRING DIAGRAM
Refer to DTC P26CA12.
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CAUTION / NOTICE / HINT
NOTICE:
- Inspect the fuses for circuits related to this system before performing the following procedure.
-
Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.
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(Select Powertrain in Health Check and then check the time stamp data.)
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-
If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.
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HINT:
Read Freeze Frame Data using the 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 help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
| 1. | CHECK TERMINAL VOLTAGE (POWER SOURCE OF WATER INLET HOUSING WITH WATER PUMP SUB-ASSEMBLY) |
| *a | Front view of wire harness connector (to Water Inlet Housing with Water Pump Sub-assembly) |
(a) Disconnect the water inlet housing with water pump sub-assembly connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| C66-5 (NWP) - Body ground | Power switch on (IG) | 11 to 14 V |
| NG | .gif) | GO TO STEP 8 |
|
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| 2. | CHECK HARNESS AND CONNECTOR (WATER INLET HOUSING WITH WATER PUMP SUB-ASSEMBLY - BODY GROUND) |
(a) Disconnect the water inlet housing with water pump sub-assembly connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| C66-3 (PGN2) - Body ground | Always | Below 1 Ω |
| C66-6 (PGND) - Body ground | Always | Below 1 Ω |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 3. | CHECK TERMINAL VOLTAGE (POWER SOURCE OF WATER INLET HOUSING WITH WATER PUMP SUB-ASSEMBLY) |
| *a | Front view of wire harness connector (to Water Inlet Housing with Water Pump Sub-assembly) |
(a) Disconnect the water inlet housing with water pump sub-assembly connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| C66-1 (+B2) - Body ground | Power switch on (IG) | 11 to 14 V |
| C66-4 (+B) - Body ground | Power switch on (IG) | 11 to 14 V |
| OK | | REPLACE WATER INLET HOUSING WITH WATER PUMP SUB-ASSEMBLY |
|
| 4. | INSPECT A/F HTR RELAY |
(a) Inspect the A/F HTR relay.
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| NG | | REPLACE A/F HTR RELAY |
|
| 5. | CHECK HARNESS AND CONNECTOR (POWER SOURCE OF A/F HTR RELAY) |
| *1 | No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly |
| *2 | A/F HTR Relay |
(a) Remove the A/F HTR relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 3 (A/F HTR relay) - Body ground | Always | 11 to 14 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - A/F HTR RELAY) |
|
| 6. | CHECK HARNESS AND CONNECTOR (A/F HTR RELAY - BODY GROUND) |
(a) Remove the A/F HTR relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 1 (A/F HTR relay) - Body ground | Always | Below 1 Ω |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 7. | CHECK HARNESS AND CONNECTOR (A/F HTR RELAY - WATER INLET HOUSING WITH WATER PUMP SUB-ASSEMBLY) |
(a) Remove the A/F HTR relay from the No. 1 engine room relay block and No. 1 junction block assembly.
(b) Disconnect the water inlet housing with water pump sub-assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| 5 (A/F HTR relay) - C66-1 (+B2) | Always | Below 1 Ω |
| 5 (A/F HTR relay) - C66-4 (+B) | Always | Below 1 Ω |
| 5 (A/F HTR relay), C66-1 (+B2) or C66-4 (+B) - Body ground and other terminals | Always | 10 kΩ or higher |
| OK | | REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN NO. 1 RELAY - A/F HTR RELAY) |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
| 8. | CHECK HARNESS AND CONNECTOR (WATER INLET HOUSING WITH WATER PUMP SUB-ASSEMBLY - ECM) |
(a) Disconnect the water inlet housing with water pump sub-assembly connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| C66-5 (NWP) - C88-51 (WPI) | Always | Below 1 Ω |
| C66-5 (NWP) or C88-51 (WPI) - Body ground and other terminals | Always | 10 kΩ or higher |
| OK | | REPLACE ECM |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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