6-24 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.
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Even if the Dower voltage to the SRS diagnostic unit is lost.
Ignition switch
the ignition capability is-retained by the condensers for more
I I than 0.5 seconds.
Multi-purpose (1) The two independent battery power supplies (from fuses
fuse 4 and 8) are connected via diodes in the diagnostic 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 IGl 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
yr DC-DC 1. When the SRS is to be repaired or parts to be replaced,
converter make sure that the negative(-) cable of the battery
L, is disconnected beforehand for insulation.
vl
L1 () 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 diagnostic unit retain for
a given period the voltage necessary for inflating the
air bag even after removal of the batteryvoltage.lf a
service attempt is made during the period, accidental
inflation could cause serious personal injury.
Safing 2. Do not measure the resistance across the terminals
impact of the SRS diagnostic unit. Do not directly touch the
sensor 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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Air bag module
19x0592