2.
Do not measure the resistance across the terminals of
the SRS diagnosis unit. Do not directly touch the test
probe to any of the terminals.
Even if an attempt is made to measure the resistance, no
correct value can be obtained because of the effects of
internal circuits. In addition, there is a danger of damage
to the gold plated portion of the
terminals.
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INTERIOR - Supplemental Restraint System (SRS)
2.
Supplying squib ignition energy
The energy for ignition of the squib is supplied by two circuits;
the battery of the vehicle and the condensers. Even if the
power voltage of the SRS diagnosis unit is lost, the ignition
capability is retained by the condensers for more than 0.5
seconds.
(1) The two independent battery power supplies (from fuses 11
and 18) are connected via diodes in the diagnosis unit. If the
voltage is larger than 9V between the connector terminal of
the unit and the ground, the squib can be ignited.
(2) The IG 1 voltage is boosted to about 25V by the DC-DC
converter to provide more in reserve than the low limit
voltage mentioned above in charging the condensers that
supply the ignition energy.
Caution
1.
When the SRS is to be repaired or parts to be replaced,
make sure that the negative (-) cable of the battery is
disconnected beforehand for insulation. After the
negative (-) cable of the battery has been disconnected,
wait for more than 60 seconds before making any
service attempt.
The condensers in the SRS diagnosis unit retains for a
given period the voltage necessary for inflating the air
bag even after removal of the battery voltage.
If a service attempt is made during the period,
accidental inflation could cause serious personal injury.
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