8ZR-FXE ENGINE CONTROL SFI SYSTEM P012800 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
DESCRIPTION
The ECM uses the engine coolant temperature sensor, installed to the water outlet and installed to the radiator pipe assembly, to monitor the operation of the thermostat.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory | Note |
|---|---|---|---|---|---|---|
| P012800 | Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) | Either of the following conditions is met (2 trip detection logic):
1.
All of the following conditions are met for 5 seconds: (a)
Cold start (b)
The engine is warmed up (c)
The engine coolant temperature is less than 75°C (167°F) 2.
All of the following conditions are met for 3 times: (a)
The engine coolant temperature is less than 75°C (167°F). (b)
The value of the change in engine coolant temperature is less than the threshold. |
·
Water inlet with thermostat sub-assembly (thermostat) ·
Cooling system ·
Engine coolant temperature sensor ·
ECM |
Comes on | DTC stored | SAE Code: P0128 |
MONITOR DESCRIPTION
- Judgment by Simulated Engine Coolant Temperature
4.917,2.323 5.302,2.594 false 3.833,2.083 3.719,0.885 3.719,0.885 3.583,0.885 false 4.656,2.615 6.302,2.958 1.646,0.344 10 false Indicated Engine Coolant Temperature Reading 3.104,3.719 5.344,3.927 2.24,0.208 10 false DTC Stored (after 2 Driving Cycles) 2.229,0.792 3.563,1.188 1.333,0.396 10 false Estimated Engine Coolant Temperature 0.708,1.698 1.833,1.896 1.125,0.198 10 false Threshold (75°C) 4.323,1.073 5.219,1.417 0.896,0.344 10 false 5 seconds 1.104,2.74 2.125,3.094 1.021,0.354 10 false Engine Coolant Temperature 2.26,3.354 2.604,3.563 0.344,0.208 10 false Time
-
The ECM estimates the engine coolant temperature based on the starting temperature, engine load, and engine speed. The ECM then compares the estimated temperature with the actual engine coolant temperature. When the estimated engine coolant temperature reaches 75°C (167°F), the ECM checks the actual engine coolant temperature. If the actual engine coolant temperature is less than 75°C (167°F), the ECM interprets this as a malfunction of the thermostat or in the engine cooling system, illuminate the MIL and stores this DTC.
- Judgment by Engine Coolant Temperature Change at High Vehicle Speed
4.146,5.573 4.5,5.573 4.5,5.573 4.677,5.365 false 2.875,3.667 3.146,3.667 3.146,3.667 3.406,4.177 false 4.104,0.5 4.26,0.729 4.26,0.729 4.479,0.729 true 3.844,3.688 4,3.917 4,3.917 4.219,3.917 false 5.229,2 5.354,1.302 5.354,1.302 5.573,1.302 false 3.823,4.938 4.021,4.938 4.021,4.938 4.156,4.708 false 1.823,2.875 2.094,2.875 2.094,2.875 2.323,2.177 false 3.688,1.521 4,1.698 0.313,0.177 10 true Fail 4.344,1.865 4.823,2.063 0.479,0.198 10 true Fail 5.656,2.042 6.135,2.24 0.479,0.198 10 true Fail 5.26,5.219 5.563,5.417 0.302,0.198 10 true Fail 1.917,0.031 2.396,0.229 0.479,0.198 10 false 17 sec. 6.479,0.156 6.958,0.354 0.479,0.198 10 false Time 1.104,3.583 2.844,4.094 1.74,0.51 10 false Engine Coolant Temperature Change Value 0.698,5.479 4.104,5.75 3.406,0.271 10 true Engine coolant temperature change judgment performed 6.198,4.948 6.865,5.458 0.667,0.51 10 false Threshold Value 5.052,2.708 6.708,3.146 1.656,0.438 10 false DTC Stored (after 2 Driving Cycles) 4.531,0.656 5.698,0.979 1.167,0.323 10 true Normal Thermostat 5.625,1.229 7.135,1.542 1.51,0.313 10 true Stuck Open Thermostat 0.063,2.781 1.802,3.292 1.74,0.51 10 false Engine Coolant Temperature Change Value 4.302,3.844 5.5,4.177 1.198,0.333 10 true Normal Thermostat 2.333,4.854 3.813,5.104 1.479,0.25 10 true Stuck Open Thermostat 2.563,0.031 3.042,0.229 0.479,0.198 10 false 17 sec. 3.24,0.031 3.719,0.229 0.479,0.198 10 false 17 sec. 3.875,0.031 4.354,0.229 0.479,0.198 10 false 17 sec. 4.542,0.031 5.021,0.229 0.479,0.198 10 false 17 sec. 5.198,0.031 5.677,0.229 0.479,0.198 10 false 17 sec. 5.823,0.031 6.302,0.229 0.479,0.198 10 false 17 sec. 3.927,3.146 4.406,3.344 0.479,0.198 10 false 17 sec.
-
When the vehicle is being driven between 65 and 128 km/h (40.625 and 80 mph) and the monitoring conditions are met, the change in engine coolant temperature is monitored. The amount of change is judged to be normal or abnormal every 17 seconds, in order to monitor the thermostat operation. If the engine coolant temperature changes more than the threshold, the thermostat is judged as normal, but if it changes less than the threshold, the thermostat is judged to be malfunctioning. If an abnormal judgment is made 3 times, the ECM assembly will illuminate the MIL and store a DTC.
MONITOR STRATEGY
| Frequency of Operation | Once per driving cycle |
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.
·When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.
Stop the engine and allow it to soak.
Connect the GTS to the DLC3.
Turn the ignition switch to ON [A].
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Data List / Coolant Temperature and Intake Air Temperature.
Check that the value of the Data List item Coolant Temperature is 56°C (133°F) or less and the value of the Data List item Intake Air Temperature is between 0 and 35°C (32 and 95°F).
Set the heater control to MAX HOT with fresh air mode selected and turn the A/C off.
Put the engine in Inspection Mode (Maintenance Mode).
Start the engine and drive the vehicle at 80 km/h (50 mph) or more for 20 minutes [B].
- CAUTION:
-
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
After the value of the Data List item Coolant Temperature stabilizes, check that it is 75°C (167°F) or higher.
- HINT:
-
If the value of the Data List item Coolant Temperature is less than 75°C (167°F) while driving the vehicle at 80 km/h (50 mph), inspect the cooling system and thermostat.
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: P012800.
Check the DTC judgment result.
| GTS 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, If the judgment result is INCOMPLETE, perform steps [D] through [G].
·[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.
With the engine stopped, leave the vehicle outside overnight [D].
Turn the ignition switch to ON [E].
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Data List / Coolant Temperature.
Check that the value of the Data List item Coolant Temperature is 25°C (77°F) or less.
Put the engine in Inspection Mode (Maintenance Mode).
Start the engine and drive the vehicle at 90 km/h (56 mph) or more for 20 minutes [F].
- CAUTION:
-
When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine / Trouble Codes [G].
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: P012800.
Check the DTC judgment result again.
| GTS 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.
·[D] to [G]: 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.
CAUTION / NOTICE / HINT
- NOTICE:
- ·
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.
(Select Powertrain in Health Check and then check the time stamp data.)
·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.
- HINT:
- ·
When this DTC is output, check the engine coolant temperature using the GTS. Enter the following menus: Powertrain / Engine / Data List / Coolant Temperature. If the value of Coolant Temperature is lower than the actual engine coolant temperature, the engine coolant temperature sensor circuit may be malfunctioning. In this case, check the wire harnesses and connectors (and their connection condition) between the ECM and the engine coolant temperature sensor first.
·Read Freeze Frame Data using the GTS. 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
Connect the GTS to the DLC3.
Turn the power switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Trouble Codes.
Read the DTCs.
- Powertrain > Engine > Trouble Codes
- 50001 372
- Result:
Result Proceed to DTC P012800 is output A DTC P012800 and other DTCs are output B
- HINT:
-
If any DTCs other than P012800 are output, troubleshoot those DTCs first.
A
B
Check for defects in the cooling system that might cause the system to be excessively cold, such as abnormal cooling fan operation or any modifications.
- Result:
Proceed to OK NG
OK
NG
Inspect the water inlet with thermostat sub-assembly (thermostat opening temperature).
- Result:
Proceed to OK NG
OK
NG
Inspect the engine coolant temperature sensor.
- HINT:
-
Perform "Inspection After Repair" after replacing the engine coolant temperature sensor.
- Result:
Proceed to OK NG
OK
NG