Toyota Tacoma manuals

Toyota Corolla Repair Manual: Circuit description

If the engine coolant temperature (ect) does not reach 75c (167f) despite sufficient warm up time has elapsed.

Dtc no

Dtc detection condition

Trouble area

P0128 Condition (a), (b) and (c):
  1.  cold start
  2.  after engine is warmed up
  3.  engine coolant temperature is less than 75c (167f)
  • Thermostat
  • cooling system
  • engine coolant temperature sensor
  • ecm

Monitor description

The ecm estimates the engine coolant temperature (ect) based on starting

The ecm estimates the engine coolant temperature (ect) based on starting temperature, engine loads, and engine speeds. The ecm then compares the estimated ect 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 will interpret this as a fault in the thermostat or engine cooling system or thermostat and set a dtc.

Monitor strategy

Typical enabling conditions

Typical enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

Component operating range

Component operating range

Monitor result (mode 06 data)

Monitor result (mode 06 data)

Refer to page 0527 for the detailed information on checking monitor status.

Refer to page 0527 for the detailed information on checking monitor status.

Coolant thermostat (coolant temperature below thermostat regulating temperature)
Dtc p0128 coolant thermostat (coolant temperature below thermostat regulating temperature) Hint: this is the purpose of the thermostat malfunction detection. ...

Inspection procedure
Hint: read freeze frame data using the hand-held tester or the obd ii scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is usefu ...

Other materials:

Other functions
■  Switching between outside air and recirculated air modes Press . The mode switches between outside air mode (indicator off) and recirculated air mode (indicator on) each time is pressed. ■ Defogging the windshield Defoggers are used to defog the windshield and front side w ...

Checking monitor status
Hint: monitor result indicates normal or malfunction of each component and system when judgment has done. 1. How to read data Connect the handheld tester to the dlc 3.  enter monitor result from diagnosis / enhanced obd ii / monitor info / monitor result on the handheld ...

Vehicle lift and support locations
1. Notice about vehicle condition when jacking up As a rule, the vehicle must be unloaded when jacking up. Never jack up or lift up the vehicle loaded with things of heavy weight.  when removing any parts of heavy weight like the engine and transmission, the center of gravity of ...

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