Honda Acura NSX 1991 Service Manual page 1305

The SRS is a safety device which, when used in conjunction with the seat belt, is designed to protect the driver by oper-
ating only when the car receives a frontal impact exceeding a certain set limit.
The system is composed of left and right dash sensors, the SRS unit (includes cowl sensor), the cable reel and airbag
assembly.
DASH SENSOR (Ll
OPERATION:
As shown in the diagram below, the left and right dash sensors are connected in parallel. The parallel sets of sensors
are connected in series by the airbag inflator circuit and the car battery. In addition, a backup power unit is connected
in parallel with the car battery. The backup power unit and the cowl sensor are located inside the SRS unit.
The SRS operational sequence is as follows:
(2) Electrical energy is supplied to the airbag inflator by the battery, or the backup power unit if the battery voltage
is too low.
At least the cowl and one dash sensor must be activated simultaneously for at least 0.002 seconds in order for the airbag
to be deployed.
Self-diagnosis system
A self-diagnosis circuit is built into the SRS unit; when the ignition switch is turned ON, the SRS warning light comes
on and goes out after about 6 seconds if the system is operating normally. If the light does not light, or does not go
out after 6 seconds, or if it comes on while dirving, this indicates an abnormality in the system. It must be inspected
and repaired as soon as possible.
DASH SENSOR (RI
SRS UNIT
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I
ASSEMBLY
CABLE REEL
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