Passenger airbag fault after sound system upgrade

[ozburb]

Had the sound system upgraded (speakers, amps, sub-base) by a professionals. When I got the car back, it started throwing airbag codes:-
SDM B0019 - passenger airbag squib circuit stage 1 voltage performance - not present
SDM B0020 - passenger airbag squib circuit stage 2 voltage performance - present

The sound system guys claim that nothing they did caused this(!!?!)

The codes only occur on startup. Once the car is running, the codes can be reset and don't re-appear until the car is stopped and restarted.

Local holden dealer was useless. Charged me $60 to reset the codes. Then wanted to book the car in again to further fault find with no indication of how much it might cost. Couldn't give me a gaurantee that they could fix it. Did not give me much confidence they were worth their exorbitant hourly rate.

These codes relate to the resistance of the circuit, and are sometimes thrown due to poor/corroded plug connections.
The fact that these codes are only thrown on startup suggests something else. Perhaps turn-on inrush for the new sound system, causing interference?

Not real keen to poke around with this stuff, but might have to if the local dealer can't be relied upon.

Anybody had similar problems/codes? Anyone know of a good airbag tech in NSW?

 

[Tasmaniak]

Where are your amps mounted? I often mount the amps under the seats which requires seat removal. To do so means disconnecting the airbag seat sensor. Should the ignition be turned on without the seats plugged in... all hell breaks loose with airbag codes. Airbag don't go off... but you get a bunch of codes. I'd verify that the yellow plugs have been reconnected. They are located beside the front outside hook under each seat. Below the plastic trim panel.

 

[Capsule]

Aren't the airbags tested only on startup? That would also explain why you don't get the codes again when driving.

 

[Tasmaniak]

Initial power on is when they are tested which is why I would query if they pulled the seats and if so ... did they plug them back in?

 

[ozburb]

The amps are installed under the drivers seat, in a fashion that did not involve removing the seat.
The error codes relate specifically to the circuit to the airbag itself in the dash. It checks for circuit resistance to be between certain values.
These codes have been known to come up due to bad or corroded plug pins. Tonight I got into the dash and unplugged the dash airbag. plug looks OK. plugged it in and out a few times to break any oxide layer that may be on the pins. Re-assembled. But no change. Fault still comes up on power up.

It can only be one of three things:- the passenger airbag in the dash, the SDM module itself under the centre console, or the cabling (and plugs) in between.

I've run out of time to try and fix myself. I'm going to take it to another holden dealer armed with this information, and see if they can competently repair.

 

[ozburb]

Took the car to a dealer, and the drama started. They phoned me up and assured me that the airbag needed replacement, quoted $830 plus $65 labour. I asked them to proceed. Went to pick the car up the next day, and was advised they were still working it. It was a dashboard out job requiring 7 hours labour at a cost of some $500. I reminded them that only the previous day they had quoted me $65. In response, they reduced their labour charge by 30%.
Also to their credit, they provided me with a loan car while mine was in the shop.
I phoned them the next day. They had completed the installation, but the airbag alarms were still up. They now advise that my wiring loom was faulty and will need to be replaced. Cost will be $500 for the loom plus another 7 hours labour. At this stage I started getting a bit upset. After several discussions with the company's representatives, I've arrived at the following conclusions:-
- They simply follow the GMH procedures for repairing this fault:- Replace the airbag. If this doesn't fix the problem, replace the wiring loom. If this doesn't fix the problem, replace the ECU. Trouble is the each step costs $1500. They don't appear to have the competance to apply testing processes to definitively determine which item is faulty from the outset. They are applying a 'trial and error' approach, by changing out components. This is OK so long as everyone understands who is accepting the risk in this process. It was certainly a surprise to me that after paying $1200, it still isn't fixed, and I could be up for thousands more.
- There is insufficient evidence that the airbag they replaced was in fact faulty.
- There are only two wires that go to this airbag. Why do they need to replace the whole loom? All they need to do is install two new wires, and splice them in. They informed me that they have no auto-electrical expertise in their workshop, and would need to subcontract that sort of work out.
- I am not confident that they are capable of carrying out these sorts of repair in any cost effective manner.
I paid them what they thought I owed them for the job so far, and have declined their further involvement.

I checked the system again with my scanner, when I got the car home. There appears to be a short on that circuit. The plugs on the airbag have a retainer that is supposed to disingage the shorting bar on the airbag when you plug it in. They are known to be somewhat troublesome. Something for me to check in more detail over the next few weeks.

I will post outcomes as more info comes to hand.

 

[Towcar]

Yes typical dealership.

No actual diagnosis skills and very hit and miss.

 

[ozburb]

Finally fixed it. Problem was faults in the wiring loom. I also discovered that the airbag actually has two firing circuits, with a plug on each end of the airbag and separate circuits back to the airbag module at the back of the centre floor console. Both circuits were faulted. One was sort of shorted, and the other was sort of open. Found the faults with a multimeter. fixed it by splicing replacement wires between the airbag module plug and the airbag plugs. Didn't try to find the fault in the loom. Hopefully other wires aren't damaged. The car is an ex police car, so it is conceivable damage occurred when installing or removing police equipment.
Finally found a circuit diagram that matched the car. This was extremely useful.
I'll have to figure out how to attach to this blog

 

[ozburb]

I think this is now attached? maybe.