trophy

Sorry Loren It was more of a question rather than a statement, forgot the ? Of course you focused on the error rather than responding like a normal human being.


Jeff. Do you know if the airbag controller shuts down the ecu in case of an accident?

Lorenfb

"Do you know if the airbag controller shuts down the ecu in case of an accident?"

The air bag pins (20/5) control the #15 power (ign sw.) for both the DME
and the immobilizer (for cars with that option). Without the #15 power
to pin 27 ('95 DME), the DME fails to function. The '96 and later requires
#15 to pin 56 of the 88 pin DME, but is not controlled by the air bag ECU.

The key point, which is what most likely occurs, is that the air bag must 'fire'
and not just have a fault code to inhibit the power to the DME. Obviously if
the air bag ECU hard previously 'fired' the air bag and is faulty, the engine
won't start.

shadow993

Loren is a smart guy! I can do almost anything, but I just hate dealing with wire diagrams.

When it comes to wiring.... I bring a sledge hammer to put a nail in.

keith

So, to bring this around full circle - get a faulty air bag controller, open it up, solder pins 5/20 together, immerse the contacts in sealant, reassemble, and plug it back in and you've got yourself an airbag deletion as Jeff originally posted. No CW (!) Light, no Airbag fault light, full functionality of DME and Immobilizer, etc.

And clean/factory in appearance.

Great way to go for RS, if you ask me. Thanks again Jeff.

keith

[QUOTE=shadow993;8287368]Loren is a smart guy! QUOTE]

Obviously this is true, but I'm still not certain what was brought to the thread?

jscott82

To update this thread with some clarifying points....

1) The controller is buried up in the dash, in the center, in front of the console... The plug is on the passenger side and it fairly easy to see, its bright orange....
Its a bitch to get it out as its held in with 4 tamper proof screws. The only way I found to get them out was to use a sharp chisel at a tangent to turn them one excruciating tap at a time.

2) Now that the controller is on the bench, hack the plug out of the unit (use chainsaw and/or dynamite as appropriate).. Seems like a shame to destroy a perfectly good unit, but what the heck...

3) To clarify one more thing, you are modifying the male plug, the one you removed from the unit, not the one on the wiring harness.

White911TTOne

Hey guys, just installed a jumper from #5 to #20 pin car starts just fine but the light is still on. All air bags were removed and also the module was removed from the car. I didn't feel like destroying the module just to get the plug out so I installed a jumper. Is the key to the airbag delete the plug or the connection between 5 and 20 pin? Thanks Mark

71-3.0-911

My understanding of the system is that once that airbag light was lit, it would take hammer access to turn it off, regardless of subsequent state changes. So, once you think you have it set up, I would put a scan tool on it and see if you can reset the codes.

Best of luck.

mgianzero

Yes, I agree with this. I was told by an experienced 993 mechanic that the airbag circuit checks the system everytime the car is started and would essentially "reset" the airbag and CW lights if everything checks out. However, when I've removed the airbag and inadvertantly powered the system it never turned itself off despite being reconnected properly until I cleared it with a PST-2 (hammer would do the same).

The other thing I've noticed is the security system seems to detect if a bad bulb is in the airbag instrument and trips the CW light. Again, I've only been able to reset it thru my PST-2. So taking the bulb out may trigger a CW is my theory. But I'll defer this to the experts here as to this logic.

Does any of this help? I apologize ahead of time if it does not.

White911TTOne

Thanks Guys, I have started the car numerous times since I have multiple projects going on at the same time. I will try to have the airbag reset when I get my RS LFW install next week. :cheers:

lopro

yes what did you use to remove the nuts? they look like special tools are required
edit: I just saw this in the 21st post ---> 1) The controller is buried up in the dash, in the center, in front of the console... The plug is on the passenger side and it fairly easy to see, its bright orange....
Its a bitch to get it out as its held in with 4 tamper proof screws. The only way I found to get them out was to use a sharp chisel at a tangent to turn them one excruciating tap at a time.

would love to remove mine and follow your instruction here

jscott82

I'm not positive about this so take what I am saying with a grain of salt... But...

It's my understanding the that the central informer module is "dumb" it just turns on whatever light that its told to by the other modules (computers). So with the airbag module removed, there is no signal sent to turn on the light... So the light "cant" come on.

In my case, the light was on. I removed the airbag controller and the light went out, but I could not start the car. After tracing the wiring I found that power is fed to the ECU via pin 5 (or 20 I cant remember which was in and which was out) from the airbag module. So the jumper feeds the ECU directly and no other systems are touched.

Been that way for 4 years and has worked flawlessly.

993KT

Let's throw some mud at this again. I have a '97, I unplugged the airbag module, airbag light is on and the car started just fine. According Loren, that might be correct for '96+.

I don't want to destroy the airbag module since it's worth good money. I think I'll just try to short pin 5 and 20 form the harness side to see if that will turn off the light. I am assuming that the airbag module is responsible for the airbag light, and there isn't another body module controller in between to latch to the airbag fault. Will report that later.

993KT

Dash light stays on after I shorted pin 5 to 20 on the harness side. Maybe there is something latching to the fault still or I need to pull another pin on the harness side up? Anyone has a wiring diagram of a '97?

Aussie Alan 993

So this old thread helped me understand how the airbag module interacts with the DME in case of an accident that deploys the airbags but there is something I can add about the light.
My car is a 95 and I had to remove my faulty airbag module for a science experiment and the engine would't start, after reading this thread I made a simple jumper and put it into the connector plug across pins 5 & 20, BINGO, car starts but airbag light is still on.
After reading the manual, I figured that the plug has short circuit bridges between certain pins which only work when it's unplugged, the one between pins 6 & 7 controls the light, so I grabbed a plastic zip tie and pushed the end into the slot adjacent to pins 6 & 7 and SUCCESS! no light.
Also worth noting is the pins for the airbags are automatically shorted to prevent any possibility of accidental airbag triggering from static charges.
Hope this helps someone else like it helped me.

Cheers
Alan