Brand:

Toyota

Model Name:

4Runner GRN210 215 UZN210 215

Manual:

Repair Manual

Section:

1Gr-Fe Engine Control System

Title:

Sfi System

  1. Description

  2. Monitor description

  3. Monitor strategy

  4. Typical enabling conditions

  5. Typical malfunction thresholds

  6. Monitor result

  7. Inspection procedure

  8. Check any other dtcs output (in addition to dtc p0128)

  9. Check cooling system

  10. Inspect thermostat

DTC P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

HINT:
This DTC relates to the thermostat.

DESCRIPTION

This DTC is set when the Engine Coolant Temperature (ECT) does not reach 75°C (167°F) despite sufficient engine warm-up time.

DTC No.
DTC Detection Conditions
Trouble Areas
P0128
Conditions (a), (b) and (c) are met for 5 seconds (2 trip detection logic):
(a) Cold start
(b) Engine warmed up
(c) ECT less than 75°C (167°F)
  1. Thermostat
  2. Cooling system
  3. ECT sensor
  4. ECM

MONITOR DESCRIPTION


TID (Test Identification Data) is assigned to each emissions-related component. 4Runner

The ECM estimates the ECT based on the starting temperature, engine loads, and engine speeds. The ECM then compares the estimated temperature with the actual ECT. When the estimated ECT reaches 75°C (167°F), the ECM checks the actual ECT. If the actual ECT is less than 75°C (167°F), the ECM interprets this as a malfunction in the thermostat or the engine cooling system and sets the DTC.

MONITOR STRATEGY


Related DTCs
P0128: Coolant Thermostat
Required Sensors / Components (Main)
Thermostat
Required Sensors / Components (Related)
Engine Coolant Temperature (ECT) sensor, Intake Air Temperature (IAT) sensor, Vehicle speed sensor, Engine cooling system
Frequency of Operation
Once per driving cycle
Duration
15 minutes
MIL Operation
2 driving cycles
Sequence of Operation
None

TYPICAL ENABLING CONDITIONS


The monitor will run whenever these DTCs are not present
P0010, P0020 (VVT VSV 1, 2), P0011, P0012 (VVT System1-Advance, Retard), P0021, P0022 (VVT System2-Adavance, Retard), P0031, P0032, P0051, P0052 (A/F Sensor heater Sensor 1), P0100, P0101, P0102, P0103 (MAF Meter), P0110, P0112, P0113 (IAT Sensor), P0115, P0116, P0117, P0118 (ECT Sensor), P0125 (Insufficient ECT for Closed Loop), P0171,P0172 (Fuel System), P0300, P0301, P0302, P0303, P0304, P0305, P0306 (Misfire), P0335 (CKP Sensor), P0340 (CMP Sensor), P0340, P0342, P0343, P0345 (VVT Sensor1, 2), P0351, P0352, P0353, P0354, P0355, P0356 (Ignitor), P0500 (VSS), P2196, P2198(A/F Sensor (Rationality)), P2A00, P2A03 (A/F Sensor (Slow Response))
Battery voltage
11 V or more
Either of following conditions met:
Condition 1 or 2
1. All of following conditions met:
Condition (a), (b) and (c)
(a) ECT at engine start - IAT at engine starts
-15° to 7°C (5° to 45°F)
(b) ECT at engine start
-10° to 56°C (14° to 133°F)
(c) IAT at engine start
-10° to 56°C (14° to 133°F)
2. All of following conditions met:
Condition (d), (e) and (f)
(d) ECT at engine start - IAT at engine start
More than 7°C (45°F)
(e) ECT at engine start
56°C (133°F) or less
(f) IAT at engine start
-10°C (14°F) or more
Accumulated time that vehicle speed is 80 mph (128km/h) or more
Less than 20 seconds

TYPICAL MALFUNCTION THRESHOLDS


Duration that all of following conditions 1 and 2 met
5 seconds or more
1. Estimated ECT
75°C (167°F) or more
2. ECT sensor output
Below 75°C (167°F)

MONITOR RESULT

Refer to Checking Monitor Status for detailed information (Click here).
The test value and test limit information are described as shown in the following table. Check the monitor result and test values after performing the monitor drive pattern (Click here).
  1. TID (Test Identification Data) is assigned to each emissions-related component.
  2. TLT (Test Limit Type):
    If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
    If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
  3. CID (Component Identification Data) is assigned to each test value.
  4. Unit Conversion is used to calculate the test value indicated on generic OBD ll scan tools.

TID $08: Thermostat
TLT
CID
Unit Conversion
Description of Test Data
Description of Test Limit
1
$01
Multiply by 0.625 and subtract 40(°C)
ECT sensor output when estimated ECT has reached to malfunction criterion
Malfunction criteria for thermostat

INSPECTION PROCEDURE

HINT:
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.
1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch on.

  1. Turn the tester on.

  1. Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

  1. Read DTCs.

    Result:

    Display (DTC Output)
    		Proceed to
    P0128
    		A
    P0128 and other DTCs
    		B
    HINT:
    If any DTCs other than P0128 are output, troubleshoot those DTCs first.


Bnext
GO TO DTC CHART
A
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2.CHECK COOLING SYSTEM

  1. Check that there is no defect in the cooling system which causes overcool, such as abnormal radiator fan operation, modified cooling system and so on.



NGnext
REPAIR OR REPLACE COOLING SYSTEM
OK
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3.INSPECT THERMOSTAT

  1. Remove the thermostat (Click here).

  1. Check the valve opening temperature of the thermostat (Click here).

    Standard:
    80° to 84°C (176° to 183°F)
    HINT:
    In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.

  1. Reinstall the thermostat (Click here).



NGnext
REPLACE THERMOSTAT
OK
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REPLACE ECM