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The document discusses Toyota's thermostat monitor system, which checks that the coolant temperature rises to at least 75°C during a driving cycle. It monitors the coolant temperature from the start of the engine using a thermostat monitor phase introduced in 2000 models. The system looks for the temperature to reach 75°C within a predetermined time period during a specified driving pattern if the starting coolant temperature is between -10°C and 35°C.

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79 views3 pages

Addition PDF

The document discusses Toyota's thermostat monitor system, which checks that the coolant temperature rises to at least 75°C during a driving cycle. It monitors the coolant temperature from the start of the engine using a thermostat monitor phase introduced in 2000 models. The system looks for the temperature to reach 75°C within a predetermined time period during a specified driving pattern if the starting coolant temperature is between -10°C and 35°C.

Uploaded by

sungjoo75
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Section 10

Additional Systems

Engine Control Systems II - Course 874


Section 10
Additional Systems

Thermostat This monitor checks for the coolant temperature to rise to a minimum
Monitor temperature of 75°C (167°F). When the coolant temperature is less than
a predetermined value at engine start, the THW value is monitored
during the first portion of the LA#4 driving cycle. The thermostat
monitor phase began with the 2000 model year and will be complete
with the 2002 model year.

Thermostat Monitor P0128

Fig. 10-1
TL874f1001

Engine Control Systems II - Course 874 10-1


Section 10

Thermostat
Monitor
DTC P0128
This chart shows the rise
in coolant temperature
during the LA#4 drive
pattern. The water
temperature counter is
also shown. Note the
point at which the ECM
checks for abnormality
(improper coolant
temperature).

Fig. 10-2
TL874f1002

Thermostat When:
Monitor
DTC P0128 • coolant temperature at engine start is > -10°C (14°F) < 35°C (95°F)
Thermostat
Malfunction • air temperature at engine start is > -10°C (14°F) < 35°C (95°F)

• during specified driving pattern and time period

• coolant temperature has not reached 75°C (167°F)

10-2 TOYOTA Technical Training

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