Airbag issues - 00588 Airbag Igniter, driver side N95 - how to troubleshoot?

[Matt Devo]

my airbag light decided to come on recently, and produces the following code:

00588 - Airbag Igniter; Driver Side (N95)
002 - Lower Limit Exceeded - MIL ON

I've tried all the usual remedies, including clearing the code, disconnecting/reconnecting the battery, and reseating the harness both at the clockspring and the airbag itself. I also checked to make sure that there wasn't a short in the harness or the connectors anywhere, and reseated the 4-pin harness going into the clockspring.

If I disconnect the airbag and clear/recheck the fault codes, I get the same code with different sub code - now it's the upper limit that's exceeded. This makes sense, since the airbag control module is checking the resistance across the airbag circuit. With the airbag disconnected, there's infinite resistance, hence the upper limit exceeded.

The lower resistance limit means that there's a short somewhere, but where? I've ruled out the harness. I can't check the airbag itself since there's a very good chance of setting it off. I can check at the clockspring, and measured that there is continuity across the two pins for the airbag circuit (pins 3 and 4), but I don't know what that tells me.

Any ideas where to go from here?

The Ross-tech page for the code simply tells me it's either the clockspring, airbag harness, or airbag itself, but doesn't give any info on how to narrow it down to which component is to blame:
http://wiki.ross-tech.com/wiki/index.php/00588

FWIW, I have the TT s-line multifunction wheel and airbag, with retrofitted B7 clockspring and steering control module. I hadn't modified the airbag harness to connect the 2 ignitors but did today to see if it would make a difference (it didn't). It's been working fine for the past 2+ years, so I don't think it's a factor here but wanted to mention it anyway. I haven't tried putting my original wheel/airbag/etc back in since it's a fair amount of effort, and if it worked it would only tell me that one of the components I already know/suspect is the issue.

[diagnosticator]

There is a TSB, #69-08-11 69, that directs the removal of the harness connector under the seat, by splicing the wires together instead. The TSB discusses "Airbag lamp ON, upper limit of side airbag exceeded", DTC 01217 001, Ignitor for side airbag, Driver's side N199, Upper limit exceeded. If you want to try this fix for the Driver's side airbag, then I recommend reviewing the TSB, as the directions are specific to the airbag circuits. The harness connector to splice will be in the wiring diagram.

[vhstejskal]

I think the TSB is 6906-05 but could that be the same issue that OP is having? Link

[Matt Devo]

thanks guys, but that TSB is for the airbag in the driver's seat, which throws the N199 code, not the steering wheel airbag, which throws the N95 code (what I have)

[vhstejskal]

So found this from the Bentley Publishers Tech Forum. "What engine do you have? 00588 - It could be a fault with the wiring, the driver's side airbag igniter, or the spiral spring/return spring. You could check display group 001 if you have a VW scan tool. It could indicate if it's the igniter. Also, have you had the steering wheel off any time recently?"

I know when I checked my airbag using VagCom the other day the advanced meatering showed me intermitent connections but this could help isolate the issue.

[diagnosticator]

Can you measure the ignitor circuit resistance from the disconnected airbag control module harness connector to the disconnected airbag igniter harness connector at the steering wheel? What is the measurement in Ohms? From either end of the ignitor circiut, is there continuity to ground? If there is, what is the resistance measured to ground?

[Matt Devo]

So found this from the Bentley Publishers Tech Forum. "What engine do you have? 00588 - It could be a fault with the wiring, the driver's side airbag igniter, or the spiral spring/return spring. You could check display group 001 if you have a VW scan tool. It could indicate if it's the igniter. Also, have you had the steering wheel off any time recently?"

I know when I checked my airbag using VagCom the other day the advanced meatering showed me intermitent connections but this could help isolate the issue.

display group 001 shows that the resistance is too low on the steering wheel igniter circuit. It only shows too low/too high/correct, so not telling me much there. It's solidly 'too low,' regardless of wheel position etc. I've had the steering wheel off plenty lately as I had to wire in the 2nd fuel sender to the cluster when I did my AWD conversion. Plus I had to replace the stepper motor in the fuel gauge so that was another time I've had it off recently. Not sure how that would factor in though.

Can you measure the ignitor circuit resistance from the disconnected airbag control module harness connector to the disconnected airbag igniter harness connector at the steering wheel? What is the measurement in Ohms? From either end of the ignitor circiut, is there continuity to ground? If there is, what is the resistance measured to ground?

not quite clear exactly where you're asking me to measure - where do you mean by the 'airbag control module harness connector'? Do you mean for me to disconnect the harness at the airbag control module itself? If so, then I'd assume I'd need to reconnect it to test continuity to ground?

[diagnosticator]

display group 001 shows that the resistance is too low on the steering wheel igniter circuit. It only shows too low/too high/correct, so not telling me much there. It's solidly 'too low,' regardless of wheel position etc. I've had the steering wheel off plenty lately as I had to wire in the 2nd fuel sender to the cluster when I did my AWD conversion. Plus I had to replace the stepper motor in the fuel gauge so that was another time I've had it off recently. Not sure how that would factor in though.



not quite clear exactly where you're asking me to measure - where do you mean by the 'airbag control module harness connector'? Do you mean for me to disconnect the harness at the airbag control module itself? If so, then I'd assume I'd need to reconnect it to test continuity to ground?

Yes, correct. You also need to disconnect the ignitor connector at the airbag on the steering wheel. Then, having identified the pin number in the controller harness connector for the driver's SW airbag, measure resistance from that pin to the airbag connector. Note the resistance value shown on the meter. This will measure the resistance of the wiring, and spiral spring from one end of the ignitor circuit to the other end at the steering wheel. After the resistance measurement from end to end, DO NOT reconnect the harness connector to the control module, then with a test probe connected to the pin on the control module harness connector, connect the other test probe to chassis ground and see if there is continuity to ground, if there is a relatively low resistance connection to chassis ground, note the resistance value shown on the meter. A reading showing there is continuity to chassis ground indicates a fault in the wiring, aka a "short to ground". The resistance should be infinitly high, or no continuity, indicated on the meter by an overlimit indicator, Fluke DVMs, show "OL" for example. The resistance of the ignitor circuit, should read a low single digit value, not higher, and not zero ohms, with no continuity to chassis ground. With the test probes connected to the control module connector pin, and at the airbag ignitor connector, turn the steering wheel and see if the resistance of the ignitor circuit changes either increasing or decreasing somewhere in the steering wheel rotation.

On the wiring diagram, the harness connector pin numbers for the ignitor, N95 are pin #33 Yellow, and pin #34 White. Measure the resistance of both circuits, from pin #33, to the N95 ignitor connector, and from pin #34 to the ignitor connector, separately. Also measure for continuity to chassis ground from each circuit separately.

[Matt Devo]

thanks, I'll do that once I get my spare control module rebuilt (per your PM), so as to avoid having to remove the center console twice

[Matt Devo]

well, the issue ended up being the airbag connector on the back side of the clockspring. The locking tab had broken, but the connector still click-locked into place, which was very deceiving. Instead of staying put however, it would slide back just enough to break the connection and cause the code/airbag light.

I now have an extra B7 clockspring available for anyone who might need it.

[vhstejskal]

Good to hear you found the issue. You'd think the airbag connectors were engineered a little better..

[rogue]

Hi guys,

I just wanted to add to this forum posting. This is exactly the same problem and solution that I had.
I have a photo for anyone looking at the forum to see what is going on here.

You are right, I am amazed at how bad this connector is for something safety related. You can put the connector in place with a "click" but as easily as it clicks into place, you can pull on it and it just comes straight off!
The "click" does not lock anything at all, and this must work itself loose over time, perhaps with movement of the steering wheel height.

Here is what I have done to rectify this. I have rolled some electrical tape over the connector. This was hard to do, because it is quite tight around the connector.
Over the top I have added a cable tie. It looks better than it really is. I could not get this very tight and you have to be careful not to pull against the plastic and risk breaking the assembly.
After my repairs, you can still pull the connector off, but it is creating enough stickiness and clamping force that the connector should stay put.

[Lusticles]

I had that. My steering wheel airbag did not go off. I'm glad the accident was not as bad as it could have been. I suggest if people have this don't ignore it like I did. Never know what may happen.