Great Wall Hover. Manual - part 92

Safety airbag-5

Test instrument

Instrument

Name

Utility

diagnostic scanner

The alarm lamp

 keeps illuminating.

Failure

 handling

Debug the

failure codes

Test the systematic failures in

SRS safety airbag system, debug
ECU. failure codes.

The basic failure diagnosis process

The failure code DTC of both present and history-accumulated failures may co-exist.

Caution

The safety airbag alarm lamp flashes for 6 times and then extinguishes when the ignition switch is in ON

       position after the installation of new safety airbag system electronic control unit, which demonstrates the

       normal function of  SRS safety airbag system. In this case the system does not need to be tested, otherwise it

       should be diagnosed and repaired.

If the alarm lamp does not illuminate when the ignition switch is in ON position, repair the alarm lamp relevant

       circuit and, then further operate to get it into work.

Scan the ECU by connecting

the scanner with k-line

Failure detection

The test for SRS safety airbag alarm lamp

SRS-ECU will execute a series of diagnosis and test to check whether the function of airbag system is prepares. The check can

prevent the restriction system from mis-explosion and ensure the necessary explosion during collision. If found the failure,

SRS-ECU will save a proper failure code and light the alarm lamp to indicate a failure status for the convenience of maintenance.

If connect the pin 2# wire 488#  (diagnosis request wire) on the diagnosis port to the ground (wire 50#) for more than 2s, the
safety airbag alarm lamp will flash the code. For detailed position refer to following figure.

safety airbag system alarm lamp

Safety airbag-6

brown white

red

diagnosis plug

black

Failure judgment

1.

Failure record (failure code storage)

When ECU determines the error through the cyclic diagnosis and test, SRS-ECU should saves the corresponding code, first

judgment time, final judgment time and number of occurrence in EEPROM.

RS-ECU can stores 6 failures at most, under voltage failure and two collision records (front and side).

Failure code approved by SRS-ECU

Serial No. 

Failure description 

Debugging 

1 

Ignition loop 1 (driver’s front airbag), resistance is too high or open-circuit. 

Can 

2 

Ignition loop 1 (driver’s side front airbag), resistance is too low or short-circuit 

Can 

3 

Ignition loop 1 (driver’s side front airbag), grounding 

Can 

4 

Ignition loop 1 (driver’s side front airbag), connected to power supply 

Can 

5 

Ignition loop 2 (passenger side front airbag), resistance is too high or open-circuit. 

Can 

6 

Ignition loop 2 (passenger side front airbag), resistance is too low or short-circuit 

Can 

7 

Ignition loop 2 (passenger side front airbag), connected to power supply 

Can 

8 

Ignition loop 2 (passenger side front airbag), connected to power supply 

Can 

9 Power 

voltage 

is 

high 

Can 

10 Power 

voltage 

is 

low 

Can 

11 

Alarm light failure, connected to power supply or lamp is short-circuit 

Can 

12 

Alarm lamp is failure- grounding or filament is open-circuit. 

Can 

13 

Shortage/failure of algorithm parameter 

Cannot (replace the 

SRS-ECU)  

14 

The front collision is recorded 

Cannot (replace the 

SRS-ECU)  

15 Communication 

failure 

Can 

16 

Internal failure (refer to following table)   

Cannot  (replace the 

SRS-ECU)  

 

 

Safety airbag-7

              Description of flash code

The failure code transmission is completed by SRS-ECU’s input to the defined diagnostic scanner through the maintenance system’s

serial data interface. (X-431 diagnostic scanner) Failure code of diagnosis

 

Failure 

Failure code 

Flash code 

1 No 

storage 

error 

 

$12 

2 

Front airbag driver’s, high resistance 

$9,021 

$21 

3 

Front airbag driver’s , low resistance 

$9,022 

$22 

4 

Front airbag driver’s,    short-circuit of GND 

$9,024 

$24 

5 

front airbag driver’s , short –circuit of VBATT 

$9,025 

$25 

6 

front airbag passenger, high resistance 

$9,015 

$15 

7 

front airbag passenger, low resistance 

$9,016 

$16 

8 

front airbag passenger , short-circuit of GND 

$9,018 

$18 

9 

Front airbag passenger , short-circuit of VBTT 

$9,019 

$19 

10 

High voltage of battery   

$9,031 

$31 

11 

Low voltage of battery 

$9,032 

$32 

12 

Failure of alarm lamp 

$9,061 

$61 

13 

Internal failure (replace SDM)   

$9,071 

$71 

14 Front 

collision 

record 

$9,051 

$51 

15 

Side collision driver’s record 

$9,056 

$56 

16 

Side collision passenger record 

$9,057 

$57 

17 

Retightened safety belt collision 

$9,058 

$58 

18 

Beyond the allowable repeat usage times 

$9,054 

$54 

 

3. Interior failure

The micro controller can test the following items not only in starting detection but also in cyclic diagnosis detection.
a. Ignition circuit triggers the transistor: The high-side transistor is detected not only in the starting detection but also in the

circulation diagnosis. But for the low-side transistor is opened when is connected to power supply directly, so the low-side

transistor only can be detected in the starting detection to avoid the misexplosion.

b. The ignition voltage is provided by the booster transformer.

c. The acceleration sensor is detected by itself when start the detection.

d.  Allowable deviation scope of acceleration sensor in circulation diagnosis.

e.  Micro controller includes (AD converter, ROM, RAM etc.)

f.  Status of safety sensor

    Cautions:

Connector of explosion tube circuit has the short-circuit bar. When the connector is not connected, the end (+) of

explosion tube is connected to end (-) directly to prevent the failure outspread caused by static. When the connector

is bas and short-circuit bar is connected, the failure may not be eliminated.

An external watch dog can detect the operating status of micro controller. It can trigger the watchdog when the micro con

troller has failure. The watch dog will reset the micro-controller and light the alarm lamp.

Safety airbag-8

       Internal failure determined by SRS-ECU

Serial 

No. 

List of failure 

Description of failure 

1 Micro-controller 

 

AD converter or EEPROM is faulty (the micro controller will be reset 
and alarm lamp is light when the RAM has failure.)   

2 

Driver’s front airbag ignition loop   

Enable the failure   
Measure the failure of loop     

 

3 

Passenger front airbag ignition loop   
 (if realized)  

Enable the failure   
Measure the failure of loop   

4 

Seat safety belt preloaded ignition loop   
(if realized)   

Enable the failure   
Measure the failure of loop   

5 

Passenger side safety belt preloaded 
ignition loop  (if realized)  

Enable the failure   
Measure the failure of loop     

6 

Driver’s side airbag ignition loop   
 (if realized)  

Enable the failure   
Measure the failure of loop     

7 

Passenger side airbag ignition loop   
  (if realized )   

Enable the failure   
Measure the failure of loop     

8 

Maximum times of explosion of safety 
belt pre-tightener 

Reach the maximum value 6 

9 

Holding time of ECU energy     
(self-supply time)   

Too short 

10 Accelerometer 

 

Deviation range 
Sensor not in constant, stable model 
Sensor tests the failure itself 

11 

The measurement of ignition loop is 
rejected continuously   

No cycling diagnosis test       (duplicated calculation) 

12 Safety 

sensor 

 

Calculate the safety sensor open-loop using the method that power-off 
for 2 or more than 2 seconds is considered as passing   

13 

Initial firing current   

All initial firing current in normal status when the front airbag releases. 

14 

The ignition of side airbag is not   
determined. 

Though SRS-ECU has received ignition information for 5 times during 
HSIS cycling ignition, the ignition can not be determined due to the side 
safety..  

 

Debug the failure codes

 Approach 1. The failure codes will be debugged following the ECU’s receipt from the X-431 diagnostic tester of the debugging

failure codes order through the serial interface, however, if an internal failure code is recorded or one impact is

recorded, the debugging will not be executed.

Approach 2. Ground 488# line for 5 times in 10 seconds to debug the failure codes.

Failure status display  (alarm lamp keeps illuminating).

1. Bulb test

SRS-ECU will light the alarm lamp in order to test the bulb after working voltage is provided to it through the battery. The lamp

will flash for 6 times and then extinguish at 1HZ in the initial phase. The alarm lamp will keep illuminating after the working

voltage is provided in order to inform the driver’s system failures. The alarm lamp will keep illuminating for 6 seconds after the

ignition on and then be extinguished if the history-accumulated failures are less than five times. In the initial phase, SRS-ECU will

not prepare to test impact and stop release till the circuit is stable. Therefore, alarm lamp’s display manner will be one of

following projects in the initial phase. (Table 4.9).

Project 1. If the impact is recorded or the number of history accumulated failures is or more than 5,the alarm lamp will keep

       illuminating, simultaneously, it will also keep illuminating if there is a possible explosion failure.