Toyota Corolla (E120): Circuit description
If the engine coolant temperature (ect) does not reach 75°c (167°f) despite sufficient warm – up time has elapsed.
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Dtc no |
Dtc detection condition |
Trouble area |
| P0128 | Condition (a), (b) and (c):
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Monitor description

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 malfunction thresholds

Component operating range

Monitor result (mode 06 data)

Refer to page 05–27 for the detailed information on checking monitor status.
Other materials:
Mechanical system tests
1. Perform mechanical system tests
Measure the stall speed.
The object of this test is to check the overall performance of the transaxle
and engine by measuring
the stall speeds in the d and r positions.
Notice:
Do the test at normal operating atf temperature 50 to 80 °c (122 to
...
On–vehicle inspection
1. Inspect brake booster
Airtightness check.
Start the engine and stop it after 1 or 2 minutes. Depress
the brake pedal several times slowly.
Hint:
if the pedal goes down farthest at the 1st time, but gradually
rises after the 2nd or 3rd time, the booster is airtight.
...
Inspection procedure
1 Check p/t squib(lh) circuit(airbag sensor assy center – front seat
outer belt assy lh)
Disconnect the negative (–) terminal cable from the battery,
and wait at least for 90 seconds.
disconnect the connectors between the airbag sensor
assy center and the seat belt pretensio ...


