Air Bag Code 10

[Tiggie]

After painting my 90, I am getting a code 10 on the airbag light.

The service manual states:
"Firing circuit disarm device blown due to deployment circuit shorted to ground. A thermal fuse is built into the diagnostic monitor that opens the battery and power supply circuit to the airbag should a short occur in the airbag deployment circuit without a safing sensor being closed."

I removed the two crash sensors in the left and right fenders during painting. I also removed the dual crash/safing sensor at the hood latch. After this time, the battery was reconnected and the car moved multiple times as it was painted. Everything is reconnected now.

I'm guessing I blew those thermal fuses in the air bag control module. The safing sensor was disconnected (open circuit I suppose). Is that a safe guess?

I believe I wrongly assumed that disconnecting the sensors would turn off the system by default.

I enjoy parts hunting but finding an air bag module for a 90 doesn't sound like fun.

[Tiggie]

Did some searching and found I can replace the thermal fuse.

Guess I'll brush up on my circuit board soldering skills.

Still have to troubleshoot to be sure there is no short per the service manual, but I suspect the issue is my roughhousing the system with the disconnected sensors. Have some other things to tackle on the project before worrying about the air bag.

[sly]

My 93 is permanently disabled due to a short in the system direct to the airbag. Not 100% sure, but mostly sure that it's in the airbag itself. Module out, bulb out of the dash, and airbag disconnected in the steering wheel.

As for replacing that thermal fuse... use those metal spring clips (the flat ones, not the alligator clips) as a heat sink on the fuse side to prevent it from melting from the heat on the board side. I've replaced that fuse in my module 3 times and then replaced it with a thermal breaker (really hard to reset, but can be done with firm solid pressure on that button). Still pops almost instantly when installed.

Good luck finding the short.

[Tiggie]

Definitely didn't think about needing the heat sink. Thanks for the tip.

I'll order a few extra in case things go bad. Do you have a source for that circuit breaker?

[friskyfrankie]

Definitely didn't think about needing the heat sink. Thanks for the tip.

I'll order a few extra in case things go bad. Do you have a source for that circuit breaker?

Amazon used to have them (probably still do) as long as you have the proper specs.

[Arquemann]

I was going to replace the thermal fuse in my Volvo 850 blower resistor since I had a source for one at 2.99€ each. Ended up just buying a new blower resistor as soldering the thermal fuse would've required high heat solder and heat sinks. The blower resistor was 18€ so YMMV in terms of cost viability and availability

[sly]

I mounted all the mess to the back side of the board and drilled a hole in the module to mount the thermal breaker. It's a bit of a kludge. I have no clue what breaker I used in there either. I never posted what I put in there.

[Tiggie]

Pulled this module out today and it's really burnt up.


The brown case is melted badly. I managed to get it off, but the 15 ohm resistor died whenever the thermal fuse blew. I really couldn't tell it was there. Got to get a resistor, and also something to tie them together.
I understand the resistor's job is to get hot and that blows the thermal fuse?
How do I know what type and wattage resistor to buy?

This whole mess seems like a fire waiting to happen. I don't have a picture but it almost burnt through the module cover. I am tempted to leave it out and forget the air bag. With the module out, there's no light or chime indicating any problem... which to me could easily translate to "good enough".

[sly]

Woof. Yeah... that was rough.

[friskyfrankie]

Looks like someone dropped acid (pun NOT intended) on that bad boy!

[Mainemantom]

I would disable the air bag system due to age. I would not want the air bag going off unexpectedly. The injury could be fatal.

[DerekTheGreat]

Whoa, that let the magic smoke out and then some.

"
I am tempted to leave it out and forget the air bag. With the module out, there's no light or chime indicating any problem... which to me could easily translate to "good enough".
"

Yep, that's what I'd do.