Reset SRS unit??

[nsx009]

Hi, I am helping a friend put back together a NA2 Man 1999 RHD Australian delivered NSX. Its very similar spec to the UK and JDM ones. The airbags deployed in a fairly minor accident and he is wondering if there is anyone in the UK or Japan that can reset the SRS unit? The USA guys can apparently only do LHD ones.

Appreciate any thoughts.
Cheers,
Scott

[Kaz-kzukNA1]

Hi, Scott.
Not sure what you meant by 'reset'. SRS controller doesn't have memory bank for the error code so the SRS light is either On or Off.
Also, while the orientation/housing design of the SRS controller is different between the RHD and LHD, the algorithm and even the internal circuit board is the same so again, not sure what you meant by 'USA guys can apparently only do (reset) LHD ones'.

If the SRS was deployed, you must replace the steering wheel SRS, passenger dashboard SRS, both R & L seatbelt SRS.
Otherwise, you will get the warning light.


Also, you must check the control unit and both R & L dashboard sensors for any damages.

In order to deploy the SRS, both the controller sensor AND one of the dashboard sensor have to be triggered so even the owner may say it was fairly small accident, I would pay extra attention because it's not that easy to trigger these sensors.
10kph or 6mph against solid and rigid wall is enough to cause substantial damages to the frame.

Kaz

[nsx009]

Hi Kaz,
Thanks for the reply, By "reset" we have been told the SRS control unit needs to be reset after it deploys the bags and seat belts. The seat belts SRS have been "reloaded" by a firm in the USA and my friend is buying both new airbags. He sent the SRS controller to the USA firm and they could not reset it. They do "reset" the USA LHD control units for $40, I gather it is a fairly easy task but they probably only have the equipment for the USA spec control unit. The SRS control unit is undamaged and looks like new inside.

So, do you think its worth trying the SRS control unit once he has installed all the new bags and seatbelt SRS units or has something got to be done to the SRS Control unit as well.

We really appreciate your input.

Scott

[Hagasan]

Hello Scott,

No idea on the resetting procedures but if you need any SRS system parts I have the control unit, both airbags (Honda not Acura), both seatbelts and both front crash sensors available...

Thanks,

Gary

[Kaz-kzukNA1]

If you have modern Honda/Acura models with SRS controller generating individual error codes, you can reset it in less than 30sec. Those models will show blinking SRS light when SCS connector was shorted.
Not on our NSX though.

These modern SRS controllers will keep the error code even you disconnect the fuse or the battery and can't be erased without following the specific sequences.
Same for the upgraded one body ABS controller on our NSX introduced from 99-00 model onwards.
With some SRS controllers, they even have accident/crush data logger feature to support accident investigation or providing precious information for the development of future safety devices.

For modern SRS, keep the IG key in P0 (Off position), short the MES (Memory Erase Signal) connector under the dash or nearby, turn the IG key in P2 (On position), wait for about 6sec until the SRS light switches off, within 4sec disconnect the short loop at the MES, SRS light comes On again, within 4sec re-connect the short loop at the MES, then the SRS light should flash twice to confirm the memory reset.
On OBD2 spec cars, there are other method used but still, similar procedures.


However, on our NSX including the final 2005 model, it's the classic single stage system. Well before the introduction of i-SRS dual stage ones.
There is no error code generated and thus, no memory to reset.


Before going any further, please note that SRS is a safety device and if the system was deployed, the golden rule is to replace the whole SRS module/controller/sensor as a set.
Please use the following info at your own risk. I have repaired the SRS module in the past for the owner only under the strict written agreements.

As you have taken out the SRS module, if you tilt it, you can hear some light metal rattling noise.
It's like the metal ball inside the paint spray can.
That's the trigger switch within the SRS controller.

There are other two switches on the car. It's the dash sensors and it's like round cylinder like body.
If you follow the yellow protective cable tube around both the driver and passenger foot area, you will find them. There is also a switch in each sensor.


Before reconnecting the new replacement modules (not the controller but the steering wheel SRS element, the passenger one and the two seat belts SRS cyl), just short the mating connectors on the chassis loom or use 2ohm resistor to simulate the modules at each connectors.
Then, put the IG key in P2 (On). If the SRS light switches itself Off, your cable and controller are fine. Then, you can connect the actual modules instead of the short circuit mockup wires to prevent accidental deploy of SRS.


Again, the rule is to replace the whole units if the car was involved in accident deploying the SRS system.


If you are thinking of getting used parts, please double check the parts no.. There are different spec available depending on the year model, RHD/LHD, etc.

Recently on NSX Prime, one member posted that although the outer case shape (and thus, the parts no. as well) is different, the internal circuit board used was exactly the same on classic Legend models and these controllers are sold at really cheap price. It's from LHD models but may be of your interest.
If you have friends in Japan, someone who can understand Japanese or if you can use translation sofware well, you may be able to get RHD version throuhg Yahoo Japan Auction or 'Rakuten' website.


While you have the SRS controller off the car, you may want to replace the capacitor and check one of the transistor inside.
Sooner or later, it will start leaking like the ones on the A/C CCU, Bose AMP, dash gauge, etc.
Example here; http://www.nsxcb.co.uk/blog.php?1811&blogcategoryid=48

Kaz

[nsx009]

Thanks Hagasan, PM sent.

[nsx009]

Hi Kaz,
Once again, Thank you so much for your input on this, its really appreciated. We now have a better understanding of the system and will be able to make a decision on the best way to get the system working and safe again. As you say replacing the units as a set looks like the best option.

Kaz, I have been following your posts and technical input for quite a while now and have found many helpful ideas and fixes for the NSX from your thoughts. Its a wonderful car from an engineering point of view and I really enjoy working on and maintaining mine and helping friends out with theirs as well. We are lucky to have people like you to assist us!

Many Thanks,
Scott

[Kaz-kzukNA1]

Good luck with the hunt for the parts. Should be able to cover everything through friend's insurance as they are OEM parts.

If you need further assistance, just post on here.

Kaz