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 having elapsed.
Monitor description
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
Typical enabling conditions
Typical malfunction thresholds
Inspection procedure
Hint:
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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.
Hint:
If any dtcs other than p0128 are output, troubleshoot those dtcs first.
Standard value: 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.
Problem symptoms table
When a "normal" code is output during a dtc check but
the problem is still occurring, use the problem symptoms
table. The suspected areas (circuits or parts) for each
problem symptom are in the table. The suspected areas
are listed in order of probability. A description of each of
the ...
If you think
something is wrong
If you notice any of the following symptoms, your vehicle probably
needs adjustment or repair. Contact your toyota dealer as
soon as possible.
Visible symptoms
Fluid leaks under the vehicle
(water dripping from the air conditioning after use is normal.)
Flat-looking tires or uneven tire w ...
Front occupant classification sensor lh circuit
malfunction
Description
The front occupant classification sensor lh circuit consists of the occupant
classification ecu and the
front occupant classification sensor lh.
Dtc b1780 is recorded when a malfunction is detected in the front occupant
classification sensor lh
circuit.
Wiring diagram
...