My 2002 VW GTI MkIV recently had the airbag warning indicator light turn on. The VW dealership wanted to charge around $600 to fix it. They told me the seatbelt latch was at fault because it had an intermittent connection issue, so I bought a new one and replaced it myself. The dealer then reset the fault code and the light turned off. However, as soon as a slid my seat to adjust it, the light came right back on. What's the problem?
I took my car to a different VW shop (not the dealership) and they fixed the problem for $160, but if I'd known the solution was just to solder the wires directly together, I could have fixed it myself. I did however, learn what the problem was thanks to them and I'll share the solution here. VW apparently knows about this issue and supposedly offers special repair kits for it. I think it applies to all the VW mk4 Jetta/Golf/GTI because they use the same connectors. The fault-code can be thrown simply by moving/sliding the front seats because the electrical connection in the wires below the front seats are poor. The intermittent connection fault-code is (usually) due to high electrical resistance in the connectors themselves. The pins have loose contact or have dirt/corrosion from oxidization, or both.
One solution is to solder each of the wires directly to their partners, bypassing the 2 yellow plastic connectors altogether (see image below). Of course, you won't be able to swap out your seat for a new one as easily, but if you're planning to keep the same seats forever this fix is very cheap, requires no electrical resistors, and still maintains the original manufacturer functionality (if your belt isn't fastened, the airbag won't deploy). This method solved the problem in my car.
Now I'm having the same fault-code appear with the passenger-side seat (I knew it was only a matter of time) and I'll be fixing it myself. The procedure:
- Disconnect the car battery.
- Snip off the 2 yellow plastic connectors related to the seat belt, but remember which wires are paired together! (See image below)
- Solder the 4 wires to their matching colors, be sure to properly insulate each of the wires.
- Wrap the whole bundle of 4 wires together to help prevent future fatigue.
- Reconnect the battery.
- Reset the fault code (a VAG-COM KKL 409.1 USB Interface diagnostic cable can do this).
If this was indeed the cause of your intermittent resistance and everything was done correctly then the warning light should stay OFF.
Battery side - belt buckle side (see image)
- brown - brown (driver seat only)
- yellow - green (driver seat only)
- brown - blue
- red - yellow (red is purple on passenger seat)
Notice that two of the wires are brown on the battery side for the driver seat. It's possible that they both go directly to the same "ground", but to be safe, try not to mix them up accidentally.
Keep in mind there is a thin and a thick brown wire that if you get the wiring reversed your scanner will trigger an airbag warning light. I gave up on this stack exchange months ago and now have revisited after going thru 3 different resistors 2.2, 3.3 and 4.7 which has worked for others. I started over thinking I messed up with assuming the brown wire was one next to the red since it was twisted with it. Not the case. Twist wired the 4 wires together to the seat belt to test and all drivers side warnings disappeared!!!