Karrera Coupe

Please Note: I have already posted this same message in my existing thread on the 924/944/968 forum re. dash replacement in resulting instrumentation and dash illumination lights and potentiometer problems. I am not sure which is the best forum for this so I am also posting it here on the dedicated 968 forum.

This past Saturday, I at long last I found the electric 'short' following my 968-dash replacement. It took me months!
On the console I had the connectors to two of the rocker switches, the one for the external rear view mirrors and the one for the central door locks, reversed. Once those two connectors were swapped, the problems with the dash illumination and the illumination potentiometer went away. My excuse: the 4 rocker switches connect to 4 harnesses numbered 1 to 4 by their factory labels. But it turns out the sequence of connecting them up is 1,2,4,3. Not the 1,2,3,4 that I assumed is the sequence.

Unfortunately, two new problems have now become evident:
1. The airbag warning light in the instrumentation cluster stays on. This causes the big red "!" light to stay on.
2. The anti-lock warning light in the instrumentation cluster comes on startup and only goes out after driving the car for a few minutes. It does not feel as if there is any problem with the brakes.

Neither of these two issues predate my dash replacement.

I left the two passenger airbags in place in the replacement (used) dash. Should I try to replace these two airbags with those that are in my original dash in an attempt to resolve this air bag warning light? Or will disconnecting those two passengers in dash airbags 'resolve the warning light'? I am not sure what the functionality of 30-year-old airbags are at the best of times.

Any ideas where I should start looking for the cause of the anti-lock warning light coming on intermittently?

My car is over due its annual state safety inspection so I am under pressure to get these warning lights solved.

I am once again desperate for advice.

Thanks in advance.
Alwyn

Zirconocene

I'm not sure that you have an actual airbag problem. Rather, I think that there are a number of conditions that can trigger that warning. Unfortunately, I think that futzing with the electrical system can be one of those things. So, to avoid the risk of messing about with 30 year old airbags, I think that the right (safer) path is to find someone that can lend you a Bosch Hammer tool (low probability), or has a Durametric tool. Even if no one you know has a Durametric tool, they are not super crazy expensive. There might be usage restrictions on the tool, so you may be forced to buy your own but it will certainly be cheaper than trying to buy a Hammer tool.

I would also guess that there is a diagnostic issue that is going on with the brakes. Maybe start by taking a look at the connections and seeing if everything is clean and making good contact.

Good luck

Karrera Coupe

Thank you very much @Zirconocene for your pointers. I will reach out to a local indy shop to see if they will rent me a Durametric. I understand from the Durametric web site that I will need a unit with a ‘round plug’. I see there is a guy on eBay that rents them
out. But his doesn’t seem to include the round plug needed for our cars.
If that doesn’t work out I may just have to go to the local Porsche dealer.

I can’t wait to be able to drive my car again after this long lay off.

Thanks again for now.

Cheers
Alwyn

Charlie

This will reset the airbag.

https://www.bergvillfx.com/products/t-obd-tool

quick968

That tool only works with OBD2 cars, the 968 is OBD1

Charlie

The Bergville tool works with the 964 and 968. I have the tool and use it on my 968 and a friends 964. You have to get the 19 pin adapter,

ihoe

The Bergwill tool do not fix the Airbag lamp on all 968's. I have visited Bergwill with my car and it did not work. But he was able to fix it with the proper Porsche diagnostic tool.

Karrera Coupe

Thank you @ihoe , @Charlie , @quick968 , and @Zirconocene for your advice so far.

I ended up taking my car to a local indy who reset my airbags fault code. That problem is now solved.

Now my last remaining known problem is that on startup I have to step on the gas a little bit to increase the rpms to around 2500 before the alternator seems to kick in. Before the alternator kicks in, the Anti Lock Brake warning light and the large ! red warning light stays on. As soon as I blib the gas pedal sending the rpm up, the large red ! warning light and the orange Anti Lock warning light go out and the battery charging system starts working per the voltage meter reading. I can't imagine why the Anti Lock brake warning light and the battery charging system may be linked but it looks like they are.

Do you have any ideas what may cause this/these problem/s and how to solve them?

Thank you in advance.
Alwyn

quick968

First guess is your alternator/voltage regulator are dying and/or your battery is not in tip top shape. It's remarkable how many systems are electrically interconnected on Porsche cars. Also, a battery that's on it's way out can cause all sorts of seemingly unrelated problems. Having to rev the engine points to a battery not providing enough starting voltage to energize the field and kick the alternator on. Have your battery load checked first since it's the easiest/cheapest item to replace. Next would be the alternator. I believe the 968 alternators are all internally regulated for voltage..

Cheers
Mikey

Zirconocene

Per PET, if it's the regulator, you can replace it separate from the alternator, similar to the 944. If you shop around a little bit, you can find it for < $30, whereas the OEM part is a little spendy. It's probably a little tricky to get your hand in where it is (for me, at least) but it just unscrews from the alternator.

Good luck