elaw

Anyone got any hints on diagnosing an airbag light on a 1990 80 quattro? In particular, is a VAG-COM of any use? The Bentley doesn't make any reference to pulling codes. I already ohmed out the clock spring and it appears okay so I'm trying to figure out where to go from here...

elaw

Well I found the problem. Or at least *a* problem... The two thingys under the back seat: the "voltage transformer" and "energy reserve" - they're missing! Yay, the joys of buying used cars.

Anyone parting a B3 and have those items for sale? :^)

Lago Blue

I don't think a VAG-Com is required.

Is it a true airbag car? "Non-airbag cars have a package shelf in front of the driver's knees" (from 20v.org). The reason I ask is that perhaps that light is something else, like a CEL that's been moved.

See also code pulling at the above reference.

elaw

Nope, unfortunately it's definitely an airbag car. I've already had the airbag out because my first thought was the clockspring in the steering wheel hub, but that tested okay which is when I started looking elsewhere.

It looks like someone on Motorgeek has the parts I need. In a way I'm relieved because this means maybe I won't have to tear the car apart looking for a wiring issue (knock on wood)!

GuyllFyre

Of course, a VAG-COM is not required but I prefer this:

Chassis Type: 8C - Audi 80 B4
Scan: 01,02,03,08,15,25,26
-------------------------------------------------------------------------------
Address 01: Engine
Controller: 8A0 906 266 A
Component: 2,8l V6 MPI 2Ventil D0C
Coding: PMC 1011
2 Faults Found:
00555 - Oxygen (Lambda) Sensor 2 (G108)
03-10 - No Signal - Intermittent
00560 - Exhaust Gas Recirculation System
27-00 - Implausible Signal
Readiness: N/A
-------------------------------------------------------------------------------
Address 08: Auto HVAC
Controller: 8A0 820 043 A
Component: Klima-Vollautomat
D51
Coding: 00062
Shop #: WSC 06322
4 Faults Found:
01271 - Positioning Motor for Temperature Flap (V68)
41-10 - Blocked or No Voltage - Intermittent
01272 - Positioning Motor for Central Flap (V70)
41-10 - Blocked or No Voltage - Intermittent
00602 - Potentiometer On Positioning Motor for Footwell/Defroster Flap (G114)
30-00 - Open or Short to B+
00604 - Potentiometer Positioning Motor for Air Flow Flap (G113)
30-00 - Open or Short to B+

Over "blink, blink blink, blink blink blink blink blink blink blink...wait, how many was that?"

elaw

But would a VAG-COM show anything for a B3? The Bentley doesn't say anything about pulling codes - I had the impression that wasn't doable for the airbag ECU on a car of that age.

elaw

Well just for the benefit of anyone searching, I got more info on this.

Apparently these cars had a recall for the airbag system. The recall work included replacing the airbag ECU and deleting the two modules ("energy reserve" and "transformer") under the back seat. I'm told they also installed an adapter harness for the new ECU that includes a diagnostic connector. Next step is to dig around in the console and see if I can find that connector!