al83s

The Official airbag light thread.
Hello everybody.
My car currently has this problem and after researching this topic on rennlist and other forums, It seems like an often occuring/reoccuring problem for 986 and 996 models. Thus I decided to start this thread to organize all the information available on this topic and save new Boxster owners a few
hours/cups of coffee in front of the computer screen. Call this a an Airbag light FAQ if you wish.
Well, here are some things I found out so far:

Airbag light cannot be reset by disconnecting the battery overnight

Autozone code reader wont help either.

Can only be reset at the deallership or with factory scan tool.

Disconnect the battery before even touching the airbags/seatbelts etc.

Seatbelt buckles often fail causing the light to come on.

Sunset is a cheap place to buy the buckles from

Buckles operate as a relay with changing resistance to tell the computer weather or not you/your passenger is buckled up and cause seatbelt pretensioners to deploy in the event of the accident if airbags deploy.

Please correct me if Im wrong or add to my list

Some things I would like more information about are if the wiring itself fails - what is the cause and place. Bad grounds? Any wiring diagrams?
What resistance do buckles suppose to have? Where is the computer for airbags located? Is there a new model of buckles, what are the part number and the changes made? Pictures?
Alex

aron in toronto

Durametric code reader will also reset the air bag light.

al83s

Hello Everybody.
Does anybody know where is the airbag computer located?

My car had an airbag light on. Scan tool showed that the seatbelt buckles were shot, so I replaced them with new ones. Tried resetting the light again, but it comes right back with same codes (seat belt buckle passenger and driver).

Just removed both seats and measured the resistance on new buckles (400ohm unbuckled, 100 ohm buckled), so do the old ones
Checked resistance on the connector with a needle and they seem to be working perfectly too.
Question is where is the airbag computer located?, so I could see if the wire is damaged on the way there.
Also, does anybody have any information on "wire harness repair kit" and what side of the harness does it modify?
Any input would be greatly apreciated.
Alex

aron in toronto

IIRC the air bag module is located behind the front console. How did you reset the light? Is it possible that the fault code was not actually cleared? I have a seat belt buckle repair "kit" sitting on a shelf that I haven't gotten around to installing yet. But from memory, I think the updates to the harness are simply better ground connections at the seat belt buckles. FYI Renntech.org has lots of airbag information.

al83s

Thanks for the info Aron.
I took the car to a reputable Porsche garage, they tried resetting it with a laptop and psc2000, fault codes came right back.
I found the computer, pulled the yellow connector and found the pins corresponding to buckle connectors (#8 passenger, #12 driver)
, put seats back in and checked the resistance between them and ground (400 ohm unbuckled, 100 ohm buckled), so the wire harness is good and grounds are good.
P.S. I bought the car with airbags deployed and replaced both airbags, both seatbelts (due to pretensioners throwing code earlier) and both buckles (all new parts). May need a new computer.
I cleaned and retightened the grounds and will have the dealer reset it tomorrow.
Thanks again
Alex

schwank

Seatbelt buckle is indeed the main cause. This is affecting my car. Have used contact cleaner to get it to go away twice (req'd reset with Durametric) but it comes back a month or so later.

I need a new buckle but Sunset gives no love to in state buyers.

al83s

Update:
Took the car to the dealer, $75 later they brought it back with light still on.
Same codes, mechanic recommended replacing buckles again
Pulled the computer connector and grounds are still good, buckles resistance is still spot on 400/100ohm.
Started wondering if there was signal going from computer to the buckles at all.
Hooked the computer back up and measured voltage from pins 8 to the ground and 12 to the ground with car running. BINGO. No voltage on either one!
Today I pulled the computer and removed the cover. No visible damage.
Question is where can I get a schematic for the computer?
Anybody rebuild their airbag computer and can share any info?

I know that the computers are VIN specific (programmed the first time they are installed and cannot be overwritten), so no used unit is going to work.
Thanks.
Alex

PTEC

You wont find an internal diagram of the control unit. I've never heard of anyone that rebuilds airbag control units.

In addition to the belt buckles causing problems a big problem causing airbag lights lies in the connector under the seat. Before you go looking for a new control unit I would suggest completing the wiring update as per the latest Porsche technical information on this repair. I believe it was released in 04. There is a repair kit that includes new terminals and plug housing that will take care of 99% of belt buckle faults if its installed correctly (I've seen A LOT of people completely butcher the wiring under the seats in what is dubbed a "repair"). If that doesn't fix your problem you'll need a new airbag triggering unit with updated software. The latest and greatest airbag control unit for 986's ends in .02 I believe but I'm not a parts guy so it may have been updated.

Tuizner

Mine was a ground.

Cable that goes to the buckle is pinched by a clip under the seat . Moved the cable along an inch and reset 0 all good for a month or two - now light is back on...

Jerrygreene

Mine has been on since 1998 with a black round electrical tape covering it till last night.

both popped.. when a 16 yr old girl went dukes of hazard thru a intercection
https://rennlist.com/forums/attachme...1&d=1469634919

Know looking for parts to restore... WTB dash, steering wheel, lft fender, Hood, Lf front head light.

xandi911

Hi guys, if i change a airbag module(light went on), getting from another car(no light), it will clean the airbag light? Or a different VIN may not work? They have VIN correlation?

sorry im confused!

Thanks alot

Macster

My info is the airbag module once it is associated with a vehicle can not be transferred to another vehicle.

In trying to track down an airbag light on with no error codes and all the usual things checked and eliminated the tech found in my car's case that a new airbag control module -- ordered because that is what the factory said was the problem -- did not extinguish the airbag warning light. However, the tech told me he did not associate the new airbag control module with my car and the airbag module could be returned and was and I was not charged for the airbag module nor the labor to try it.

What did extinguish the airbag warning light was a borrowed instrument cluster, borrowed from another Boxster with the owner's permission.

So the diagnosis was my Boxster's instrument cluster was the problem. The cluster was sent to VDORepair in Lake Havasu City, AZ and some things were done but the airbag light remained on. (VDORepair did not charge for whatever it did.)

I lived with the airbag warning light on for a while then when I had the car in again the instrument cluster was again sent out for repair -- at my request -- to a different named repair facility -- AutoParts.Repair I think -- but I think essentially the same facility as before. Same people for I talked to the same people at this new facility. The repair tech claimed the problem was not in the instrument cluster but with the car's wiring. I do not recall what he said exactly but he made a convincing case for this.

The tech who had told me the problem was in the cluster had left the dealer in the meantime and I began to doubt his diagnosis.

However, I was at the dealer just a short few weeks ago discussing this with the SM when the tech appeared. He had rejoined the dealership. We talked and he said this is often the case: The instrument cluster repair facility insists the problem is with the wiring when it is in fact with the cluster.

The last time I talked with the instrument cluster repair tech he told me there is one other step he can take which is to essentially replace my cluster with a cluster from a donor car. He can transfer what is unique to my car -- the odometer reading and possibly some other things -- to the donor cluster. The cost is not prohibitive either.

But I decided not to bother this time. Maybe next time I have the Boxster in I'll have the cluster removed and sent out for repair. Third time's the charm.

kderry

I hate to break it to you macster, but it sounds like you're getting the run-around and both parties that advised you are clueless.

The cluster is read only when it comes to the airbag light. Basically, the cluster receives a signal when there is an airbag fault. That signal passes to an optocoupler that isolates it from the cluster and trips the light. If the optocoupler fails (being the only airbag circuit related component in the cluster that can fail), the light can never illuminate, not the other way around. I'll take a look at one of my parts clusters and the schematics to verify, but I see no way it could be your cluster. Have you had it on a Durametric to verify that the airbag control unit has no faults (independent testing on your own)? Are you sure the borrowed cluster had a good bulb in the airbag light and had sufficient time to talk to the airbag controller?
What year?

I don't really hang out here (ghost town), but I'll try to check back soon.

Macster

The explanation I received is the cluster LEDs share a common power line which is "hot" all the time the key is on. The LEDs are illuminated by driving an output pin low to effect a ground and thus complete the circuit. The default is these outputs are low so the LEDs are all lit at engine start time. As soon as the various controllers run through their checks they signal the cluster controller to drive the LED ground control pins to high thus extinquishing them.

That one is on suggests the output chip has suffered a failed output pin that can no longer be controller and thus the LED is on all the time.

MB2Porsche

Hate to resurrect this 3-year-old post, but I had the airbag light on and was able to just clear the codes myself. But the reason I am posting here is to share this article that helped me with the steps.

https://www.youcanic.com/wiki/porsche-airbag-problems