Airbag Light ON, no flashing

[berguy]

Hey guys, new here but not new to my Ranger.

1995 4 cylinder, single cab, manual, 2WD.

- Airbag light ON.
- Horn works.
- NO codes on FORScan, other than a P1000 after disconnecting battery (for working on airbag system).
- Burnt electronics smell from Air Bag Module. Nothing visibly burnt inside.

I cannot find wires going to the seat belt tensioner. So I have not inspected this plug.
There is no yellow plug under either seat.
Fuse 2 & 15 rang.

Assuming this isn’t related, but in case it is—ABS light comes on every now and then at highway speeds, and turns off when truck restarts.

Getting super frustrated with this one. I do electronics troubleshooting & repairs for a living and it bugs the heck out of me that schematics aren’t available to make troubleshooting this system easier. The best I found is Airbag Module schematics for a 96, which I don’t believe is the same based on ohming pins out. It did help me understand the system though.

Any help is greatly appreciated as this truck is used by my buddy for our business (his livelihood).

 

[Dirtman]

Not to insult your intelligence. But is the passengers switch off? Or possibly not working? IIRC turning the switch off turns the airbag light on. If it's not physically turned off, its still a simple switch that could be disconnected.

Just guessing, someone else will probably have a better idea.

 

[berguy]

Not to insult your intelligence. But is the passengers switch off? Or possibly not working? IIRC turning the switch off turns the airbag light on. If it's not physically turned off, its still a simple switch that could be disconnected.

Just guessing, someone else will probably have a better idea.

No offense taken. This one doesn’t have a passenger Airbag light that I’ve found, so I haven’t found a switch either. There are two wires above the glove box (when I open it) that go to where an airbag would be, so I could be missing this switch.

 

[berguy]

Update: this truck does not have a passenger airbag. I pulled the entire front driver seat out. No additional wires for a pressure pad. Looking for a plug around the seatbelt tensioner & checking dummy resistor on passenger airbag cover now. I suppose I’ll need to check passenger side seatbelt too.

Does anyone know anything else to check? I’m running out of ideas. May ohm out clock spring after disconnecting airbag next, but the horn works.

 

[adsm08]

I vote for just placing electrical tape over the light and ignoring it.

 

[berguy]

I vote for just placing electrical tape over the light and ignoring it.

If I were the one driving just around town I wouldn’t mind too much. But we live in a busy city with a lot of stupidity, my buddy drives it a lot for our biz, worried about the liability and such.

 

[berguy]

Update: spring read 0.7 ohms on each leg. This is a self shorting connection, when connector is removed it causes clock spring to short out. So I jammed some wire down in the pins under steering wheel and verified wires individually.

Seatbelt does not have electrical connections, it looks like some sort of mechanical system that will break a tab and release the ball bearings if you lock it manually and put enough force on it (ie in a wreck).

No airbag pressure pads or wiring harness in seats, they’re removed freely when bolts are removed.

Passenger airbag dummy resistor reading 2.2 ohms.

Also tested all wires to ground and no shorts so far.

All ohming was done with airbag removed.

 

[adsm08]

If I were the one driving just around town I wouldn’t mind too much. But we live in a busy city with a lot of stupidity, my buddy drives it a lot for our biz, worried about the liability and such.

Moreso than the libaility of an actual bomb sitting in the steering wheel?

 

[berguy]

Moreso than the libaility of an actual bomb sitting in the steering wheel?

At least I tried!

Kidding, but really, I have an obligation as does he to make sure any known hazards are addressed, including “safety” systems reporting an issue. So far so good on the airbags not going off without reason.

I think I forgot to mention the seatbelt would not hold. Spring broken in belt receiver. I’m borrowing female side of passenger seatbelt until I can find a good driver side one.

At this point I believe it’s the module. I found a slightly browned maybe burnt trace in it. So I will simply wait for the part to come in, swap it, and report back! There doesn’t seem to be much info out there on this so I’ve been tearing the truck down and trying to relay what I do find.

 

[adsm08]

At least I tried!

Kidding, but really, I have an obligation as does he to make sure any known hazards are addressed, including “safety” systems reporting an issue. So far so good on the airbags not going off without reason.

I think I forgot to mention the seatbelt would not hold. Spring broken in belt receiver. I’m borrowing female side of passenger seatbelt until I can find a good driver side one.

1) The airbags do not "go off without reason". In fact, if the light is on the system is disabled and they won't go off at all. Many people assume that if the light is on there is a chance of the air bag deploying on it's own, the opposite is true.

2) If the driver's seat belt is not fully and properly operational that needs to be fixed BEFORE the airbag system is repaired. This is very important. Life and death kind of important.

The SUPPLEMENTAL RESTRAINT SYSTEM is calibrated with the assumption that the driver is wearing a properly operating PRIMARY RESTRAINT SYSTEM. On any airbag system, but especially on those first generation POS systems, there is a drastically increased risk of death from having an airbag deploy without the seat belt vs having no seat belt and no airbag. This happens because the explosive charge designed to hit you in the face at the end of the accident was designed assuming your head is in a particular position relative to the steering wheel. When your head is closer to the steering wheel and at a different angle, because you were not properly restrained before the impact, air bags tend to do things like break your neck and kill you.

 

[berguy]

1) The airbags do not "go off without reason". In fact, if the light is on the system is disabled and they won't go off at all. Many people assume that if the light is on there is a chance of the air bag deploying on it's own, the opposite is true.

2) If the driver's seat belt is not fully and properly operational that needs to be fixed BEFORE the airbag system is repaired. This is very important. Life and death kind of important.

The SUPPLEMENTAL RESTRAINT SYSTEM is calibrated with the assumption that the driver is wearing a properly operating PRIMARY RESTRAINT SYSTEM. On any airbag system, but especially on those first generation POS systems, there is a drastically increased risk of death from having an airbag deploy without the seat belt vs having no seat belt and no airbag. This happens because the explosive charge designed to hit you in the face at the end of the accident was designed assuming your head is in a particular position relative to the steering wheel. When your head is closer to the steering wheel and at a different angle, because you were not properly restrained before the impact, air bags tend to do things like break your neck and kill you.

Thanks for the info! I did not know that or think about the airbag being functional without seatbelt. The seatbelt is and has been first priority, but my temporary solution was to move passenger side female receiver over. It looks like it will work as a temporary fix but will confirm when seats are back in.

I confirmed the seatbelt does automatically lock when pulled too fast. So all good there!

 

[adsm08]

Thanks for the info! I did not know that or think about the airbag being functional without seatbelt. The seatbelt is and has been first priority, but my temporary solution was to move passenger side female receiver over. It looks like it will work as a temporary fix but will confirm when seats are back in.

I confirmed the seatbelt does automatically lock when pulled too fast. So all good there!

Good.

I don't see a problem with as long as it bolts down on the driver's side, and it should.

Lots of people don't think about that, and not wanting to wear their seat belts wrap it behind the seat and buckle it there. IMO there should be a position sensor of some sort on the driver's seat belt, and if the computer doesn't see it move every few key cycles it throws on the air bag light and disables that system as well.

 

[berguy]

Just wanted to report back.

Replacing airbag module fixed my light that was ON and was not blinking. From my understanding if you have no blinks it is likely total failure of the system (ie bad module), as most other things should result in a blinking code.

Next is the alternator as I believe that may have killed it. Could be wrong but read that this could kill it. Lights are flickering a little along with voltage gauge going up and down rapidly. So either way it’s time.

Thanks for the input everyone!