Caution:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation.

Crankshaft position sensor
InspectionDisposal
Hint:
When scrapping a vehicle equipped with srs or disposing of
the front seat side airbag, be sure to deploy the airbag first in
accordance with the procedure described below. If any
abnormality occurs with the airbag deployment, contact the
service dept. Of toyota motor sales, u.S.A., Inc.
...
Spiral cable
Components
Removal
Caution:
Be sure to read the precautionary notices concerning the
srs airbag system before servicing it (see page rs-1).
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery ...
Replacement
Replace timing chain cover oil seal
Hint:
There are 2 methods to replace the oil seal.
If the timing chain cover is removed from the
cylinder block:
Using a screwdriver and hammer, tap out the
oil seal.
Apply multi-purpose grease to the lip of a new
oil seal.
Notice:
...