Help: Airbag light DOESN'T come on!

The airbag light on my 2006 DC never comes on and the passenger side always reads "Airbag off". I took it to my local dealership and they diagnosed a shorted out driver's side buckle wiring, and a faulty occupant sensor ECU (the one under the passenger seat). They offered to fix it for the low, low price of $1,060. I told them I'd get back to them ...

My fear is that they'll fix those two items and discover that there's more to it than that. I've read through the variety of threads on here about airbag problems and from what I can tell, there are two ECUs at work in the system - the occupant sensor, and the center airbag ECU. It seems to me that if the occupant sensor was shorted out, the other ECU would cause the light on the dash to illuminate. Wouldn't it? Since I'm not getting a light at all (and they did check the bulb on the instrument cluster), it seems to me that there's more to it than just those two items they want to replace.

I'm tempted to just purchase and replace those two items myself (yes, I understand the inherent danger in fiddling with the SRS system), and then see what happens. If I were to do that, is there any recalibration that needs to be done, or is it just plug and play for that sensor/ECU?

I'm still on the fence about how to proceed, so I'd appreciate any information/advice from the airbag experts in the forum.

Thanks in advance.

 

My professional advice is that when it comes to airbags, and any other safety devices, don't risk it. Leave it to the professionals. The last thing you want is to make a mistake that costs someone their life, or serious injury. Working with airbags is dangerous, and you can seriously hurt yourself.

However, in answer to your questions:
When a system fails it can fail in more than one way. That includes failing and not illuminating the airbag warning light, failing and properly illuminating the warning light, or the failure is only in a portion of the system, and part of the system can still remain functional. Since the passengers airbag off warning light is on, that is sufficient warning. What this normally indicates is that the passenger's system is disabled, but the driver's system is not. (Hence no dash warning light) If you do choose to work on it yourself then I suggest two things: DISCONNECT THE BATTERY before you start, and READ the service manual. Don't go by "Joe on the forums said you could do this". The last thing you want is to be working on your system and accidentally discharge an inflator. Remember that the airbag's main ECU has an INTERNAL battery that allows it to still discharge the inflators in the case where an accident or other problems would cut power from the main battery. SO ALWAYS BE CAREFUL.

My initial suggestion still stands. Let the pros handle your airbag system.

 

Thanks for the reply, Bill. Unfortunately, I NEVER get an SRS light. Not even when I first turn the key to on. The light on the instrument cluster should illuminate as the ECU goes through its self test and then either go out or stay illuminated to indicate a fault. It does none of those things, which leads me to believe there is more going on than just the occupant sensor malfunctioning.

 

That could be a circuit board failure or a bad LED. I have a custom made harness for 2nd Gens so that I can test each of the LEDs on the cluster. I use it for when I do custom LED conversions.

 

The dealership checked that and said the indicator light is good.

 

Strange. If they can test the light, and verify it is good, then the DERM should be able to light it up. It is a simple ground input to the cluster to turn that on.

 

So, when I questioned them about this today, they told me the ECU under the seat is fried, which has basically shut down the whole system, keeping the lights from coming on, or anything else from working. Apparently the Center Sensor Assembly isn't a computer at all, it just takes input from the variety of components it connects to and re-directs it. They did say that they stand by their work, so if anything else is wrong, it will be covered in the quoted price of $1,060. I did some checking and the ECU and seatbelt buckle are like $350, and I've already paid them $200 to diagnose it to this point. That means I'd be paying them about $500 in additional labor to fix it. Plus, from what I read in the service manual, that ECU requires some callibration for it to work properly. In the long run, it might be better to just let them do it.

 

Yeah, like I said, some things are best left for the professionals. Good luck, and make sure to update us all on how things went.

 

SRS systems are better left to the pros. You will drive better knowing that it was done right and if you get in an accident, it will work like it's suppose too.

 

So, to wrap this all up, I've finally got a fully-functional SRS (airbag) system.

My first visit to the dealership cost me about $1,000, and they replaced the passenger seatbelt buckle and the passenger ECU. When they gave it back to me they told me that the light still wasn't coming on and that the cluster was likely bad. They offered to replace it for another $1k, but recommended that I just leave it like that and have them check it each time I brought it in for scheduled maintenance ... yah right.

I wasn't happy with that answers, of course, so I took the instrument cluster apart and discovered that the previous owner had put tape in between the led on the circuit board and the faceplate. Once I removed the tape, the light worked just fine. That told me that the dealership hadn't tested the light as they said they did (and charged me for). When I brought that up they told me there was some confusion between the tech and the advisor, blah, blah, blah. The advisor said he was going to check with his manager and see what they could do about it.

After that, the system worked fine for about two weeks and then I started getting an airbag light randomly. Eventually it just stayed on. When I took it back they bent over backward to help me troubleshoot it, after the whole air bag light fiasco. They eventually discovered that someone had spliced into the harness at some point. I have NO IDEA why, but the butt connectors they had used to splice it back together were shorting out, so they replaced the whole harness, and now everything works perfectly. I had to pay for the harness, but they didn't charge me anything for labor.

Total cost for everything from start to finish: @$1,400. I wasn't thrilled about paying that much, but the peace of mind knowing the system is functional when I have my family in the truck is well worth the cost.