Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Toyota vehicle intrusion protection system / Ignition switch circuit / Circuit description
Toyota Corolla (E120): Circuit description
If the ignition switch is turned to the on position, battery positive voltage is applied to the switches, such as terminal ig of the ecu.
Wiring diagram

Other materials:
Overhaul
Hint: components:
1. Remove rear wheel
2. Remove spare wheel cover assy
3. Remove rear floor finish plate
4. Remove luggage compartment trim cover inner lh
5. Remove rear shock absorber with coil spring
Support the rear axle beam with jack.
Remove the 2 nuts and bolt.
...
On–vehicle inspection
1. Inspect cooling system for leaks
Caution:
to avoid the danger of being burned, do not remove the radiator
cap while the engine and radiator are still hot, as fluid
and steam can be blown out under pressure.
fill the radiator with coolant and attach a radiator cap tester.
  ...
Inspection procedure
1 Check d squib circuit(airbag sensor assy center – horn button
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 horn button assy.
release the airbag ...


