Driver airbag high resistance

[Polo6R_flashred]

My Polo developed a fault for the airbag and identified from VCDS as driver airbag igniter high resistance.

Have checked the airbag power wiring behind steering column to the clock spring down to the two pin connector to the airbag itself.

With the two pin air bag connector disconnected and jumping the connector with a paperclip VCDS shows resistance as normal means wiring leading up to the connector right before the airbag is fine.

Previously cleaned the contacts and ensure ample fit and the code went away for awhile but always come back. Have tried replacing clock spring and multi-function connector but problem remain the same. Have not tried Stabilant 22.

Initially I always reckoned it was wiring related but now it looks more like the actual airbag itself is failing.

My question:
1. Has anyone faced this problem and ultimately end up replacing the airbag?
2. Has anyone used multimeter to measure resistance of the airbag (Understood there are sites stating potentially setting off the airbag with multimeter)?
3. Has anyone used VCDS output testing the airbag controller?

other advice welcome.

[iichel]

I'm afraid you're facing a serious safety issue and it's good to hear you've taken action to investigate.
Never should you measure the resistance of the airbag itself, given the danger of setting it off.
Given the fact that all wiring seems to be allright, my suspicions are with the airbag itself. It is an extensive part to replace but it appears to be the logical suspect.

I would probably verify the wire from the driver airbag, starting at the airbag module with one tip of the multimeter and ending at the yellow connector of the airbag (disconnect from airbag itself)
If this shows 0 ohms of resistance on both wires, replace airbag.

If there is little resistance, I'd investigate wiring and connectors.

[Polo6R_flashred]

Hi Iichel,

Thanks for replying really appreciate it. Initially thought it was the airbag itself but seems that is not the case anymore. I had another look at the wiring and managed to get some more information from VCDS.

When the fault was present with airbag in place VCDS measured resistance was 8 ohms; VCDS resistance too high.

After cleaning the connectors and pins, with airbag installed VCDS resistance reads around 4 ohms. VCDS resistance correct.

with airbag disconnected and shorting the connector (not the airbag itself but the connector that connects to the airbag) VCDS resistance reads around 2 ohms. VCDS resistance correct.

I've also took out the clockspring with everything disconnected and measure with digital multimeter it reads around 1 ohms (actual reading around 1.6 ohms, multimeter internal resistance around 0.5ohms)

by shorting the two pins on the connector before connecting to the clockspring hovers just under 1.9 ohms. VCDS resistance too low.

So a few more questions..
1. Is 4 ohms normal? comparing front passenger airbag igniter resistance reads around 2 ohms. Read somewhere the accepted range is between 2 to 6 ohms.
2. If airbag internal resistance is around 2 ohms, means the internal resistance of the wiring leading up to the airbag is 2 ohms too. Shouldn't the wiring internal resistance be a lot lower than 2 ohms?
3. What should be the expected internal resistance for the clockspring?

[iichel]

Yes around 4 should be OK. But never ever put a multimeter on an airbag, unless you'd like it to go off Static electricity from a multimeter could set it off.
The wiring should not have any significant resistance and neither should the clockspring.
If the airbag module is happy with the resistance, leave it in, clear the codes and drive happily.