SRS light on, searched, few questions?

I can't seem to find anything specifically in the manual that describes what determines the light being turned on? Got in this morning and the SRS light was on, found a blown SRS fuse. Disconnected the airbag module, and fuse does not blow. Reinstalled and started car, and fuse immediately blows. The light stays on even with the module disconnected. I take it there is some micro controller or fail safe to the light being on? Was thinking about getting an aftermarket wheel anyway, just trying to figure out what turns it on when the module itself is removed.

If you go to the service manual (links on the NSX Wiki) I think you will find that the SRS controller stores trouble codes. I expect that once a trouble code is set the light will stay on until you reset the controller. The manual should give you the procedure for retrieving the trouble codes and resetting the light. A failed air bag unit or a failed (or removed) fuse will probably generate trouble codes.

I couldn't find it in the manual, though it's kind of a pain to track down in a pdf. If I'm unplugging the actual airbag module, how is the light still on is what I'm saying? I'm assuming the light defaults to on unless the module turns it off. All I see are the two g sensors, srs control unit, spiral cable, and wiring.

in my 1997 manual it is page 24-18 for light stays on continuously troubleshooting.

Inside the dash gauge, there is a circuit that controls the SRS warning light.
There is self diag circuit inside the SRS controller that monitors all the SRS related sensors, inflator(s), wiring, etc and it will change one of the controller's output port telling the gauge unit to switch off the SRS light.

Therefore, if you blew the SRS fuse, disconnect the SRS controller, disconnect inflator module at the steering wheel, damage the cable reel (clockspring) or other related loom, the gauge unit won't receive the required signal from the SRS controller that it will keep the SRS light On.

When you said 'disconnected the airbag module and fuse does not blow', did you mean the inflator module at the steering wheel or the gold colour SRS controller sitting at the bottom of the centre console?

If you were referring to the inflator module at the steering wheel, did you connect the red short connector instead before powering up the SRS controller to check the fuse?


Kaz

I disconnected the center air bag sensor/module, in the console. That's what I was looking for Kaz, so sounds like my module is bad at this point. We usually call that the "center air bag sensor" at toyota, and all data was calling it the "air bag control module" for this car. The module itself is then turning the light out when it gets a good check of the air bag resistances, so with it disconnected I'm going to have the light stay on from what you're saying since I no longer have the module commanding the light off?

Correct.
If you disconnect the SRS controller, the gauge unit won't receive the required status signal to switch the SRS light Off so it will stay On permanently.
If you blew the SRS fuse #1 inside the cabin or disconnect any of the sensors or the inflator modules (the one at the steering wheel, passenger SRS, the seat belt pre-tentioner depending on the year model/spec) without creating mockup circuit, it will also trigger the SRS light.






Photo is probably easier.

The SRS controller sitting under the centre console.
Please ignore the parts/model no. as it's different depending on the RHD/LHD, year model, etc.








Inside the SRS controller, there is a silver square block and that is the roller spring sensor for the impact detection.
You will hear the roller moving if you gently shake the unit.

Please note that unlike the modern SRS controller, there is no memory device to store the error/history code.















The inflator module on the steering wheel and the cable reel (clockfuse) at the bottom (1st photo).
Please keep the red short terminal connected whenever disconnecting the inflator module for your safety.











If you are blowing the SRS fuse #1 inside the cabin and if you don't have any other short circuit, from what you wrote so far, very likely that you have leaky capacitor issue inside the SRS controller.
You can check it by opening it.

It's a safety device so you should replace it with a new one (though, probably LHD one is discontinued) and not repair or use the 2nd hand one.
If you find the leaky cap issue inside, you may want contacting [MENTION=7588]Briank[/MENTION] on here.
He may be able to help you under strict agreement.

There was someone on here who found out that although the outer case design was different, the internal circuit board was exactly the same on the ancient Legend model.
Personally, I won't use 2nd hand safety module with unknown history and whether it's the same spec as yours depends on the year model but another option.

Extra info here;
http://www.nsxcb.co.uk/blog.php?1811&blogcategoryid=48


Kaz

You might be able to dummy up a signal to keep the light on the dash off but I would not sell a car that has a safety system inoperative and not show that.

Briank said:

You might be able to dummy up a signal to keep the light on the dash off but I would not sell a car that has a safety system inoperative and not show that.

Click to expand...

I don't think I ever intend to sell this car. I'm off this week, so I might try to pull the module and open it up and peek inside. See if there aren't obvious caps bad or something like that.

If it is blowing fuses it has at least bad capacitors.

Briank said:

If it is blowing fuses it has at least bad capacitors.

Click to expand...

I believe I have a friend with a working unit laying around, so if I have to compare some burned up unreadable caps it should be doable. Haven't seen anyone really doing repair, so see how it goes later this week.

Not many people what to work on the SRS units because of the liability. The ones I have seen the capacitors just leak.

I don't think you ever stated the vintage of your car. I don't know about early cars; but, from1997 on the NSX was definitely equipped with pre tensioners in the seatbelts. The pre tensioners are controlled by the SRS module. Removing or disabling the SRS module will result in no pre tensioner operation.

Something to consider.