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(3) Clear DTCs

When ECU diagnostic tester (Hi-DSTM) receives the "Clear DTCs" command from the serial interface,

the DTCs stored in ECU will be cleared off. But if an internal DTC is recorded or there is one crash

record, the command will not be executed.

5. Trouble display (Warning light ON)

(1) Light bulb check

When working voltage is supplied to SRS ECU (HAE2.5) through battery, SRS ECU (HAE2.5) lights up

the warning light to check the light bulb. In the initiation stage, the light will be on for 6s at the frequency

of 1Hz and then go out. To give notice of the presence of troubles to the driver, the warning light will

remain on after the working voltage is supplied. If the history troubles happened for less than 5 times, the

warning light will be on for 6s after ignition on and then go out.  In the initiation stage, the SRS ECU

(HAE2.5) will not check crash and arrest deployment until the circuit of SRS ECU (HAE2.5) goes

stable.

Thus, after ignition on, the display mode of the warning light is one of the following states displayed in the

initiation stage:

STATE 1) The warning light will remain on if there is crash record or the history records of the trouble

are no less than 5 times. Meanwhile, the warning light will remain on if there is explosion trouble.

STATE 2) The history troubles are no less 1 time but less than 5.

("Low battery voltage" shall be excluded from the total number of the troubles.))

STATE 3) Normal (i.e. there is no explosion trouble or history trouble.))

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(2) Trouble indication

1

In case of a trouble, the warning light will indicate. If the external trouble is a history trouble, the indication

will be cancelled. When the history trouble happens for no less than 5 times, the indicator light will remain

on even if there is no more trouble. "Low battery voltage" shall not be counted in the total number of

troubles.

2

Only a service worker can reset a displayed or history trouble. The internal troubles of a SRS ECU

(HAE2.5) or the "crash record" of a trouble cannot be reset, in which case the SRS ECU (HAE2.5) shall

be replaced.

(3) Microcontroller-independent warning light on

Microcontroller with definitive troubles cannot fulfill its functions, thus cannot control the warning light. In

this case, the warning light will light up through proper circuit regardless of the microcontroller as stated

below:

Malfunction of the battery supplying power to SRS ECU (HAE2.5): the warning lights are turned

on continuously by means of the drive function of the selfcheck light.

Loss of internal working voltage: the warning light remains on.

Reset due to trigger failure of the watchdog: the warning light blinks.

Microcontroller out of work: the warning light always lights up.

Incomplete insertion of SRS ECU (HAE2.5) connector: the warning light remains on by means of

a shorting bar.

The diagnostic procedures can well be illustrated as follows:

If it is found that the SRS warning light remains on, follow the undermentioned procedures to check even if

the light goes out eventually. First, a scan meter is used to check the location of the trouble.

Then£¬go on with the checking in accordance with specific methods and procedures for the correspondent

location.

a. If the result indicates that it is an internal trouble or that the SRS is already detonated, replace the

ECU directly.

b. Troubleshooting.

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Section 2 Troubleshooting

I. LIST OF TROUBLES

1. SRS warning light OFF

DIAGNOSTIC PROCEDURES

When performing the first diagnostic check, it is advised to shake slightly the harness and connector to see if

there is any discontinuous poor contact in circuit. If there is such a problem, make sure that the connections

of the connector, terminals and wire harness are correct and undamaged. Otherwise, follow these procedures:

(1) Check other wire harnesses and instrument cluster indicator lights

1

Turn the ignition switch ON.

2

Any other light on?

Yes: turn the ignition switch to LOCK, and continue with the next step.

No: check the power supply and ground system (fuse) of the instrument cluster, and continue with step 5.

(2) Check light bulb

CAUTION:

Mishandling of SRS components may release unexpectedly airbag and seat belt pretensioner, probably lead-

ing to a serious accident. Read the service cautions before handling a SRS component.

1

Turn the ignition switch to LOCK.

2

Disconnect the negative (-) terminal cable from the battery and wait for at least 60s.

3

Remove the instrument cluster.

4

Measure and see if the two pins of the SRS warning light is triggered.

Yes: continue with next step.

No: replace the bulb of the warning light.

   Trouble

Checking Status

Possible Cause

·Loss of voltage (fuse circuit break)

·Instrument cluster trouble

·Trouble of wire harness between instrument

cluster and ECU

SRS warning light OFF SRS warning circuit trouble

1

SRS warning light is OFF

SRS warning circuit trouble.

No.

 Troubleshooting Items

Description

2

SRS warning light remains on

SRS warning circuit trouble or external trouble.

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(3)Check the connection between ECU and instrument cluster

1

Turn the ignition switch to LOCK.

2

Disconnect the negative (-) terminal cable from the battery.

3

Disconnect the connector of instrument cluster.

4

Check if the related circuits of the warning light are connected or not.

Yes: continue with next step.

No: replace the wire harness, and then continue with step 5.

2. SRS warning light remains on.

DIAGNOSTIC PROCEDURES

To begin the check, first use special diagnostic instruments and ECU to perform communication diagnosis

and find out the causes of the trouble. If the communication fails, continue with the following procedures:

(1) Check battery

1

Check battery voltage.

2

Is voltage higher than 9V?

Yes: continue with next step.

No: Insufficient battery supply. Check the charging/discharging system, and then continue with step (5).

(2) Check the continuity of the wire harness between ECU and instrument cluster

1

Turn the ignition switch to LOCK.

2

Disconnect negative (-) terminal cable from the battery.

3

Open the guard plate of the central passage.

4

Disconnect the connector of the instrument cluster.

5

Connect the negative (-) terminal cable of the battery.

6

Turn the ignition switch ON.

7

Check whether the voltage of the connector terminal of the instrument is 12V (power supply and instrument

connecting wire).

Trouble

Checking Status

Possible Cause

 

Insufficient battery supply

 ECU internal trouble

 SRS warning light trouble of instrument cluster

 Improper connection of ECU connector

 

Poor contact of instrument cluster connector

 Open circuit or poor contact of ECU power supply fuse

 

Poor connection of ECU connector terminal

 Poor contact of the wire harness between ECU

connector terminal and ground

 Driver or passenger side circuit trouble of SRS

SRS warning light

remains on

SRS warning light

remains on