Nissan Qashqai SRS diagnose

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Nissan Qashqai SRS diagnose

Postby victor2k » Sun Aug 13, 2017 11:32 am

Hello,
On a 2007 Nissan Qashqai 1.5 DCI I have some SRS strange faults(at the same time my KTS read opencircuit/shortcircuit on the front driver side:B1049,B1052,B1054,B1057).The wires was checked,no short circuit,no open circuits was found.The driver airbag +SRS spire was replaced with a known resistence,the same faults was reported.
How I can check the signals from SRS ECU without any interference?A clampmeter will show some good signal?
Is safe to use a clampmeter for this kind of measurement?Is forbidden to measure the resistence of the driver airbag but I can use a scope to check the signal from SRS to airbag igniter?
Thank you.
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Re: Nissan Qashqai SRS diagnose

Postby vasek » Sun Aug 13, 2017 12:40 pm

Hi.
Multimeter is not able to activate the airbag module in measurement mode.
Little current and little voltage.
But it is strictly prohibited by all manufacturers for safety purposes.
Those cranks from you-tube who activate an air bag module do it with large voltage and current.
The SRS ECU has drivers for airbag module ,side curtain, pre-tensioners.
These drivers are in constant monitoring of the circuit airbag module ,sending such a signal.
SRS DRIVER CONTROL SIGNAL.jpg


The signal is fed simultaneously on both sides of the the airbag module.
The delta signal - information to the driver.
The current minimum,so it's hard to see it with a clampmeter.
To control the resistance of circuit ,you should test the circuit from the ecu connector to the output on the spiral cable by multimeter,placed emulator resistance 1.0-1.5 om on spiral cable.
You should also check the status of shortener jumper on the module.

Sorry for machine translate.
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Re: Nissan Qashqai SRS diagnose

Postby STC » Sun Aug 13, 2017 1:40 pm

Victor

How I can check the signals from SRS ECU without any interference?A clampmeter will show some good signal?
Is safe to use a clampmeter for this kind of measurement?


You could but there are easier and better ways of getting a diagnostic decision !

Is forbidden to measure the resistence of the driver airbag but I can use a scope to check the signal from SRS to airbag igniter?


Yes keep the Voltmeter well away and do not measure resistance across a detonator EVER !!!

This is not a job for the scope, although you could measure volt drop from Module to Airbag. Again there are easier and better ways of getting a diagnostic decision !

KTS read opencircuit/shortcircuit on the front driver side:B1049,B1052,B1054,B1057).The wires was checked,no short circuit,no open circuits was found.The driver airbag +SRS spire was replaced with a known resistence,the same faults was reported.


With that fault description I would be looking at the SIDE airbag, either in the seat or the curtain. Not the One in the steering wheel.

One of the easiest ways to test wiring and module is to un plug the airbag or pre tensioner to get an open circuit fault. Then short the wires together to get a Short circuit fault.

Does KTS give you and Actual Data for the different airbags ?

B1047 OBD Code Definition:
Driver Side, Side Mount Airbag cross link to another firing loop


That would lead me to start testing with an emulator close to the Module. Water in the plug ?
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Re: Nissan Qashqai SRS diagnose

Postby STC » Sun Aug 13, 2017 2:14 pm

Multimeter is not able to activate the airbag module in measurement mode.
Little current and little voltage.


Using a Multimeter / Voltmeter / Any Instrument is VERY WRONG !!! and DANGEROUS !!! and should be deleted !!!

Although I concede that there are SOME Voltmeters that may not push enough Current or Voltage, there are far MORE that WIll & DO !!! You have no clue what Victor is Using ?

IIRC Mercedes recommend one that is airbag safe - I Would not trust it on a device that is Compressed to 200 Bar, that's before it is detonated, and will blow at 200mph with the potential to take your head clean off your shoulders.
I have set a few off (in a controlled environment) to make them safe, bit of fun and learning. They are not a toy, and will damage a brick wall !!!


Why work on these systems if you don't have that basic knowledge / training ?? You're not ever going to make enough money from them for it to be worth the risk !!

We have a regular contributor on this forum that had one go off and narrowly missed him, luckily he lives to tell the tale. He may or may not want to add / share his experience here. (He was not using a Multimeter I believe)
Last edited by STC on Sun Aug 13, 2017 3:59 pm, edited 1 time in total.
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Re: Nissan Qashqai SRS diagnose

Postby vasek » Sun Aug 13, 2017 2:49 pm

In the answer - there are no words that you can measure the resistance of the airbag module with a multimeter.
On the contrary it is written that it is forbidden to do.
The answer is written and explained why current probe - not a helper.
The answer is written that you can do the measurement of circuit by placing an emulator on connector cable.
To measure from the connector side of the ecu to spiral cable .
So you can have three status.
1. open circuit
2. short circuit jumper safety
3. normal resistance of the emulator
In addition ,if You have the emulator instead of the airbag module ,You can see on oscillogram internal fault SRS ECU.
PS.It is not clear how You read it.
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Re: Nissan Qashqai SRS diagnose

Postby STC » Sun Aug 13, 2017 4:02 pm

Something got lost in translation in your first reply. In the second reply your advice / information is correct as far as I know it to be.

PS.It is not clear how You read it.


Multimeter is not able to activate the airbag module ..... ...... .... .
Little current and little voltage.


I read that as the Multimeter does not have Enough Voltage or Current to activate the Airbag ...... ..... .... Which of course it can have ?? !!

I think others may read it that too, perhaps DIY'ers at home ? (this is an open forum accessible to all) You know how some cannot refrain from poking & prodding to get a quick fix :) :)
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Re: Nissan Qashqai SRS diagnose

Postby victor2k » Sun Aug 13, 2017 5:56 pm

STC wrote:
Does KTS give you and Actual Data for the different airbags ?

B1047 OBD Code Definition:
Driver Side, Side Mount Airbag cross link to another firing loop


That would lead me to start testing with an emulator close to the Module. Water in the plug ?

Hello,
No data list available in KTS.And the description of faults was taken from ESI fault list.
Also using Nissan ESM B1049,B1054-Driver airbag circuit open;B1052,B1057-Driver airbag circuit shortcitcuit. :(
How can be at the same time open and shorted?Wires was checked between SRS ECU and airbag spire,no faults was found.
An emulator was used instead of driver airbag...so why I must check other airbags or pretensioners?
Regards.
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Re: Nissan Qashqai SRS diagnose

Postby STC » Sun Aug 13, 2017 7:17 pm

An emulator was used instead of driver airbag...so why I must check other airbags or pretensioners?


So what are you saying? the module is faulty ?
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Re: Nissan Qashqai SRS diagnose

Postby victor2k » Sun Aug 13, 2017 7:29 pm

STC wrote:
An emulator was used instead of driver airbag...so why I must check other airbags or pretensioners?


So what are you saying? the module is faulty ?

Yes .
But the question is the same:is a safe way to check the signals?Using emulators in place of airbags?Using a clampmeter or some back pins (like in the inductive sensors measurement using 2 inputs and AC coupling)?I will try to make some captures when a new unit will arrive...
Thank you
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Re: Nissan Qashqai SRS diagnose

Postby STC » Sun Aug 13, 2017 9:13 pm

But the question is the same: What is a safe way to check the signals?


The safe / only way is to replace the Airbag with an emulator, if it does not cure it then check again at the module with the 2 Airbag pins removed from the connector - that will eliminate wiring issues too confirming the module at fault. All that is left is to confirm the module powers and grounds.

There is no need to check the signals from the module with a scope, unless it is for curiosity or learning. Of course the Module will be sending some bias into at least one line looking for the correct resistance, short or open.
If the emulator will not clear the fault and wiring is good then it is a new module.

In 25 years + I have yet to see a faulty Airbag. It is always connectors, wiring, spirals or modules.
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