Air Bag Odyssey: or, how I spent my afternoon

So, I got my car fixed – heater core, some sort of hose, the radiator too I think, plus a serpentine belt and one or two minor other issues. I picked it up, and it was purring like a kitten, except for one thing: “SERVICE AIR BAG”. I couldn’t see any of the other sensor readings (temperature, etc) because of this. My mechanic said he thought maybe the sensor got messed up when the heater core exploded and spit steam all over the place. Fair enough, I figured it was the sensor in the engine somewhere that can tell if you have an accident.

I’m pretty good with computers, and I figured out how to talk to the one in my car quite a while ago. You hold down two buttons when you start it up, and it goes into diagnostic mode – you can cycle through the menus, read out the codes, and even trigger stuff, like turn the horn or the lights on with software. It’s fun.

I dug through there and looked up the codes at various online sources, and figured out that the trouble was this:

SDM B1136 Discr. Sensor Open or Short to Voltage

OK, I’m looking for an air bag “discr” sensor, probably discrete or discriminating. I told my mechanic I was going to buy the part, and he said he’d install it for free. Cool.

I went over to Felix Cadillac, which is near some other errands I needed to run, and first talked to the service people. They were total dicks – I would have possibly had them do some work if they were nice to me. I didn’t want to do any work there if I could help it, though – I’d have to get a ride to and from home, and they’re probably more expensive, and my guy said he’d do it for free since I already paid him for other work. The guy I was talking to said “well, it could be that part, but the computer runs wires through every light and everything, it could be a totally different thing.” Umm, OK, maybe, but then what’s the point of this computer thing? Sounds to me like it’s just one part, and I bet you can figure out what part it is in under sixty seconds. Bye bye, douchebag.

So I went to the parts section and asked again for the an air bag “discr” sensor, to go with that B1136 code. “Oh, we can’t find a part from that, you have to go to the service section, they have all the manuals, you have to deal with them.”

grr. I went to KFC for a bite and searched a little more on my phone. I found a page with the exact name of the part, and instructions on how to move it out of the way for other work. I went back to the parts department.

“Can you get me the part if I have it’s exact name? I need an ‘inflatable restraint front end discriminating sensor’”
“Oh, no, I need a part number, where is that on the car? It’s the air bag, is that in the steering column”
“Well, no I don’t have the diagrams, I can’t see them on my phone, but I’d bet it’s in the front end somewhere, right? Are you telling me there is more than one part for a 1997 Cadillac Deville called an ‘inflatable restraint front end discriminating sensor’?”
“Maybe. I need to know where on the car that is.”

grrrrrrrr. So, I stood around for two minutes and searched on my phone some more, and this time found a page that explained EXACTLY how to diagnose and repair this part. If I really wanted to, I could figure out how to bypass it with a 1 ohm resistor. I still couldn’t see the diagrams, but I found something that said it was “behind the hood hinge”.

I went back in and talked to a THIRD guy in the parts department. This one was helpful. He even found me a DIAGRAM of where the damn thing goes. They kept trying to talk me out of buying the part, and going to the service department. NO!

So, he found the part, was going to order it. Thursday. I said fine, it was going to be almost $100. I had to wait for the girl to ring me up. I waited. And I waited. And finally I thought to myself “self, before you buy this $100 part that you can’t take back, maybe you should just look and make sure they remembered to plug it back in.”

So, I went back, popped the hood, and funny thing, there was a plug hanging, just above the radiator, of exactly the size and shape I would expect the plug for this part to be. I couldn’t see anywhere to plug it in, though, I figured it was behind the radiator.

I went back in and asked the parts people if I could pay on the phone later for the part if I need it, but first I want my mechanic to make sure he can’t just plug it back in. They said no, I had to pay now, or lose out on the only instance of the part I needed. Well, I figured that I could probably find it on the Internet cheaper anyway, maybe taken out of a used car, the guy was nice enough to give me a photocopy of the incomplete receipt (with the part number, “162030 SENSOR 14.865”, and I could see he marked it up $10), and I was kind enough to say “Whoops, I’m so clumsy” and accidentally drop a $10 bill on his counter as I made a hasty retreat.

I went back to my garage. I told my mechanic the story, and brought him over to the car, and opened the hood for the punch line of the unplugged cable. He got the junior mechanic out, the one that worked on the car, and he explained (mostly in Spanish, que yo hablo) that the part had broken off, and that was worried about plugging it back in.

Well, that makes sense. This part needs to be attached to the car securely, because if it hits something while it’s swinging, it could trigger the air bag, which would Suck. The plastic was broken, which I could see because HE FOUND THE PART AND BROUGHT IT OUT!

I went politely ballistic on them, and said ‘why the fuck didn’t you say anything? I spent two hours tracking this down!!’ – my guy apologized, said he had forgotten about it, and the junior mechanic drilled a new hole in the part and affixed it securely above the radiator, and now it is just plain fixed.

My trust of the mechanic is slightly bruised, but not gone – I know they just aren’t very good with the computers and electrical stuff, but that’s OK with me, because I am good with that stuff. I’ll keep going there.

But the real moral here, if you want one, is about intellectual property. GM tries to keep their internal documentation secret, like their own little DMCA, and tries to stop consumers from getting access to this information at every step. After all, cars aren’t that complicated, anyone can understand how they work. air + fuel + spark = boom, and all the rest is just a corollary. Is your mechanic really smarter than you? No, he’s just bought the books and some special tools. I’m not saying I can fix things…

but if you’re putting some kind of DRM between me and the data I want, and making it unreasonable to get the information I need – I would have had to pay $200 at least for service and parts to fix this at the dealer – I WILL make an end run around you and find the information somewhere else.

Got to give us what we want
Gotta give us what we need
Our freedom of speech is freedom or death
We got to fight the powers that be
Lemme hear you say
Fight the power

Public Enemy

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