Need help diagnosing "Service Air Bag"

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dkad260

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2012 XL Denali.

This is what comes up on the Tech 2.

Screenshot_20230528-122701_Gallery.jpg

Screenshot_20230528-122845_Gallery.jpg

Hopefully just a sensor up front. The code will not clear also, comes right back.
 
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Fless

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Likely the clockspring, but possibly the airbag. You can substitute a resistor in the clockspring's airbag circuit (at the clockspring connector to the airbag) to determine if it's a circuit problem (clockspring) or the airbag itself.

I'd recommend disconnecting the battery, discharging the electrical system, and pulling the airbag. Remove and inspect the connectors that go to the airbag and use some electrical contact cleaner (like DeOxit) on them, reassemble, and check again for codes. While you have it apart you could test the circuit with a resistor, bypassing the airbag.
 
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dkad260

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Thanks, I'll do that. Looks like all of this circuitry is under the airbag cover?
 
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dkad260

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I removed the airbag today, all the connections are clean. I removed the two connectors and re-installed but the "Service Air Bag" light still illuminated as soon as the key was turned.

I assume the "Loop 1 Resistance" as shown in the Tech 2 is through the airbag itself?
 

TollKeeper

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I would also have to suggest replacing the clock spring.

And they can be expensive, and a pain, to do. $170 part (GM), plus tearing down the column, and putting it back together.
 
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dkad260

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Update on this after my vacation last week.

For about 8 days, I had no Service Airbag warning on, but when I returned home, the next day it showed up again.

Today I pulled the steering wheel, removed the clock spring, and I ohm tested the 4 wires from the two airbag connectors back to the module inside the LH of the dash, all tested .4-.5 ohms...no variations when turning the clock spring.

I also tested the brown and black 2-wire connector and the same result.

I don't see any signs of chafing or damaged wires.

What specifically is "Loop 1"? Is this inside the airbag?

I don't have any experience with checking the resistance of an inflator, I don't want to mess with it unless I can safely measure it per the service manual.

The airbag recall was performed back in Feb 2021, not sure if that will help my case. I spoke with the dealer and they sounded adamant that the warning light would not be caused by the inflator itself.... :think: I mean of there's resistance in the inflator one would think it's plausible but I don't know.
 
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dkad260

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Further progress and hopefully a possible closure.

I pulled both front impact sensors and tested the resistance, both measured 2.9-3 ohms. I seated and reseated both connectors a few times, no visible signs of corrosion.

I removed all the locking harnesses from the module inside the driver's door behind the removable panel, checked for corrosion and seated then reseated all of them a few times.

All the wires from here that I could trace back to the wheel I checked the ohms and wiggled all the connections, no variation in the resistance. As stated earlier, all were about .5 ohms on the DMM.


Screenshot_20230629-181816_Gallery.jpg

After checking the ohms from this connector back to the wheel, I seated and reseated a few times.

Screenshot_20230629-181337_Gallery.jpg

I checked all the connections from the clockspring into and around the kick panel for broken wires, corrosion, and all looked good.

So I put it all back together, hooked up the NEG terminal, no puff of smoke....lol......and no Service Airbag light.

Checked it with the Tech 2 and the resistance looks ok, didn't like to see the 2.9 ohms with the 2.5 ohms on loop 1 and 2 respectively. Maybe that's how it should be but I'll keep an eye on it.

I will also be 1st in line for a safety inspection tomorrow...lol.

Hopefully it was a bad connection, fingers crossed.

Screenshot_20230629-180631_Gallery.jpg

Screenshot_20230629-180610_Gallery.jpg
 

TollKeeper

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Those are way different OHM readings from the ones you posted on the other site...

Screenshot_20230628-202636_Gallery.jpg

Loop 2 stayed the same, but loop 1 is completely different.
 
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dkad260

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Those are way different OHM readings from the ones you posted on the other site...

View attachment 402947

Loop 2 stayed the same, but loop 1 is completely different.

Both screenshots are the same prior to pulling connectors.

The subsequent screenshot of 2.9 ohms on loop 1 was today after I tore into all the wiring.
 

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