Seat Belt Warning Light??

[Buffjamr]

My seat belt warning light would occasionally come on under acceleration as well as some various other electrical anomolies.

I also blew my head lights and fog lights out recently after they would get really bright and then dim. After much research I determined it was probably the alternator going bad. R & R my alternator and now all is well.

I didn't see any references when I searched to the seat belt warning light so I thought I'd post to save someone else the misery of tracing electrical issues.

If you get the light, 5-7 seconds while driving (at least in an '89 Carrera) it might be the alternator.

[flatsixjunky]

My car ('89 Carrera) used to do that, after that started a foul smell started invading the cabin, it was the battery boiling. Have you had a foul smell invade the cabin too? In my case it was the voltage regulator, there are few threads about voltage regulators and in some of them the seat belt light is a common denominator.

[86 911 Targa]

Originally Posted by Buffjamr

My seat belt warning light would occasionally come on under acceleration as well as some various other electrical anomolies.

I also blew my head lights and fog lights out recently after they would get really bright and then dim. After much research I determined it was probably the alternator going bad. R & R my alternator and now all is well.

I didn't see any references when I searched to the seat belt warning light so I thought I'd post to save someone else the misery of tracing electrical issues.

If you get the light, 5-7 seconds while driving (at least in an '89 Carrera) it might be the alternator.

Voltage regulator!!!

Batteries have been known to explode.

Your VR was probably putting out 17V instead of the normal 13.5-14.5 volts.

Good luck,

Gerry

[NoSub]

I am experiencing the same thing as Buffjamr. I'll be driving along, and all of a sudden the headlights will become brighter and the seat belt light lights. I put a voltage meter on the battery, and it is at 12.65 off, and between 13.4 and 13.9 at idle and 2000 rpm, which from what I can tell, appears to be within acceptable range. During testing though, I wasn't experience the seat belt light lighting or the lights brightening. Does this point more towards the Voltage regulator or more towards the alternator?

[Tim L]

Does this point more towards the Voltage regulator or more towards the alternator?

Voltage regulator!

[Peter Zimmermann]

Originally Posted by NoSub

I am experiencing the same thing as Buffjamr. I'll be driving along, and all of a sudden the headlights will become brighter and the seat belt light lights. I put a voltage meter on the battery, and it is at 12.65 off, and between 13.4 and 13.9 at idle and 2000 rpm, which from what I can tell, appears to be within acceptable range. During testing though, I wasn't experience the seat belt light lighting or the lights brightening. Does this point more towards the Voltage regulator or more towards the alternator?

Usually, when the seat belt light symptom occurs, or when the alternator warning light actually works correctly, the VR is replaced, but the alternator should always be rebuilt at the same time. Fresh diodes and slip rings will insure that the alternator will last as long as the new regulator.

[911 Rod]

Mine did the same ..... VR was the proble,

[darrin]

me too -- be sure to check under and around your battery for acid damage. Mine happened in the early 1990s when I first got the car and resulted in a blown tach (fixed by north hollywood) and a DME computer failure (fixed by a guy who worked for NASA in alabama).

[NoSub]

Sounds like some serious damage is possible to the electrical components. Looks like I'm going to be pulling the alternator this weekend.

[Buffjamr]

I'm sure it was the VR but since the alternator was 21 yr old I decided to replace the whole thing because it wasn't exactly fun taking all that apart.

I never got the weird electrical indications unless I was underway and usually under acceleration. i couldn't duplicate it and check the voltage sitting in the garage.

It was definitely boiling the battery. I didn't have any overflow but when I would check after driving you could hear it boiling.

Everythings been good to go since the swap.

[Buffjamr]

By the way Nosub, the alternator fan strap is a PITA. I ended up replancing it with the Rennline one.

[NoSub]

Took the alternator to a trusted shop, and they diagnosed it as the voltage regulator. The rest of the alternator was okay. I've been driving it for the past 3 weeks, without any issues. Its nice not having the seatbelt light on or having the headlights surge. My battery was okay, so I'm glad I caught it when I did. Thanks everyone for the advice.

[tcar]

Be VERY careful.

Bad VR can cause all kinds of problems, not the least of which is a FIRE.

I know of an entire wiring harness burning up. Over $6k to replace!

I also know of a car that burnt up to unsalvageable.