Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / System voltage / Monitor description
Toyota Corolla (E120): Monitor description
The battery supplies electricity to the ecm even when the ignition switch is off. This electricity allows the ecm store data such as dtc history, freeze frame data, fuel trim values, and other data. If the battery voltage falls below a minimum level, the ecm will conclude that there is a fault in the power supply circuit. At the next engine start, the ecm will turn on the mil and a dtc will be set.
Monitor strategy
*1: The dtc is set immediately. The mil will be illuminated after the next engine start.
Typical enabling conditions
Typical malfunction thresholds
Wiring diagram
Other materials:
Circuit description
Refer to dtc p0115
Dtc no.
Dtc detection condition
Trouble area
P0125
If the engine coolant temperature (ect) was less than –6.6 °C
(20 °F) when starting the engine, and 20 minutes after the engine
start, the ect sensor still indicates below 20 °C (68 ...
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.
...
Circuit description
1 Check p squib circuit(airbag sensor assy center – instrument
panel passenger airbag assy)
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 instrument panel ...