Mitsubishi Eclipse. Technical Information Manual (1994) - part 83

   Supplemental Restraint System (SRS)

Inflator

The inflator has a squib, ignition cord (fuse), priming
powder, gas generator, filter, etc. put in an aluminum
container and is installed inside the air bag module.
On one side of the inflator is the harness through
which an ignition current flows. When the current
flowing through the harness reaches the squib, a
small quantity of powder is burned to ignite the

ignition cord. The cord burns the priming powder

and the generated heat causes the gas generator

to burn. Combusion of the gas generator produces

nitorogen gas quickly, which is sent to the inside
of the air bag through the filter.

The filter eliminates cinders, lowers the gas tempera-
ture and reduce the gas generator noise.
The inflator has a shorting clip provided at the con-

nector of the squib harness in the same manner

as the driver’s side inflator.

Harness

Ignition cord (fuse)

Filter

Priming powder

I

Gas 

Air bag deployment [in case of 50 km/h (30 mph) frontal
impact]
(1) OPERATION FOR APPROXIMATELY 15 MILLISECONDS

AFTER THE COLLISION

If a strong impact produced by a collision is detected by

either of the front impact sensors and the safing impact 
sensor in approximately 10 milliseconds after the collision,
the SRS diagnostic unit will supply an ignition signal to
the squib.

In approximately 3 milliseconds after the ignition signal
has been supplied to the squib, gas generation will begin.

   Supplemental Restraint System 

(2) In approximately 20 milliseconds after the collision, the

air bag folded in the pad cover will begin to inflate, the
pad cover will break at its crease, and the air bag will
expand outward.

(3) In approximately 35 milliseconds after the collision, the

inflated air bag will touch the chest of the driver.

(4) In approximately 40 milliseconds after the collision, the

air bag will be fully inflated.

(5) In approximately 55 milliseconds after the collision, the

pressure of the driver against the air bag causes the gas

to escape through the two exhaust holes on the rear of
the module, and the deflation helps lessen the impact im-
posed on the driver.

(6) In approximately 105 milliseconds after the collision, the

air bag that has absorbed the impact will rapidly deflate,
providing visibility for the driver.

   

 Restraint System 

SRS DIAGNOSTIC UNIT

The SRS diagnostic unit monitors the impact 

sors, squib, wiring harness, condensers, battery 
age etc. If it detects a problem, it illuminates the
“SRS” warning light to alert the driver. It also stores
in memory what the problem is, and the duration
of the problem (the duration during which the 
ing light stayed ON).
The condensers provided in the diagnostic unit 

 electric energy during the period the ignition

switch is ON. This supplies squib ignition current,
even if the power cable from the battery is broken
by the collision, to inflate the air bag as soon as
the front impact sensor and safing impact sensor
are simultaneously switched ON.

Caution
Make sure that the SRS diagnostic unit is never
disassembled.

1. Monitoring function

The SRS diagnostic unit monitors the wiring harness and SRS
components shown in the following table to check whether
they satisfy the specified values. When the ignition key is in
“ON” or “START” position, the SRS warning light should illumi-
nate for about 7 seconds and then turn off.

This indicates that the SRS system is in operational order.

If the SRS warning light does any of the following, immediate

inspection is needed.
(1) The SRS warning light does not illuminate as described

above.

(2) The SRS warning light stays on for more than 7 seconds.
(3) The SRS warning light illuminates while driving.

The fault data is stored in terms of a diagnostic code in the

non-volatile memory 

 The duration of the fault

is also stored in terms of the ON duration of the warning light.

Component

Front impact sensor

Air 

bag module (Driver’s side)

Air bag module (Passenger’s side)

Condenser

Cranking detection circuit

Main Monitoring 

Point

Short circuit

Open-circuit once

Open-circuit twice

Short circuit

Open circuit

Short circuit

Open circuit

Terminal voltage high

Terminal voltage low

Cranking signal detection 

time

Diagnostic Code No.

11

12

13

21

22

24

25

31

32

3 3 ”

INTERIOR   Supplemental Restraint System (SRS)

Component

Main Monitoring Point

Diagnostic Code No.

Double lock connector

Unlock or lock switch open-circuited

Battery

 voltage low (Multi-purpose fuse No. 4 is blown)

 voltage low (Multi-purpose fuse No. 8 is blown)

External circuit open-circuited or short-circuited

SRS warning light

Drive circuit defective

44

SRS diagnostic unit

NOTE

 EEPROM   Electrically Erasable Programmable ROM

A ROM to which data can be stored and be electrically written and from which data can be electrically erased.
**: Equipped. with the automatic diagnosis code erasure function. (Refer to