Please tell me what is wrong with my car.

[old_skul]

Here's the deal: I'll be driving along, and as I accelerate in 2nd or 3rd gear, the seatbelt warning buzzer and light come on. And I'm wearing my seatbelt already. And the door's not open.

At night, this behavior is accompanied by all the lights in the car getting temporarily brighter - like way brighter. The headlights, the instrument lighting, even the freakin' radio lights get super-bright for a moment.

I just replaced my battery - but it was doing this before that.

I do *not* get an alternator light.

Do I have a bad regulator? TIA for your diagnosis, folks...

[nostatic]

doesn't that fit with high voltage? I seem to recall discussions about bad voltage regulators and/or alternators spiking at 17 volts or so.

[Botman]

Short in the ground to the seat belt recepticle on the drivers side? My Carrera has two wires that run up the seat belt recepticle that I assumed were for the seat belt warning. Just a shot in the dark, though.

[Doug Zielke]

Grounding & connections. (90% of old car electrical problems.)

[Tyson Schmidt]

Alternator is overcharging. Could be a poor alternator-to-engine ground strap. Or a bad voltage regulator. On yours it is built-in, so alternator replacement is necessary.

[Superman]

Yep. You can verify this with a voltmeter. Hook it up anywhere and watch system voltage. I'll bet it's spiking. above 15.

[Dignan]

Mark,
Sell it and get a good ole SC. then you won't have problems like this.. as for the fixing the problem, i have no idea really I fear Electrical Grems.......


Eric Mckenna
78SC

[old_skul]

Nah, Eric, SCs are too complex for small brains like mine. I have to stick with somewhat more simplistic ignition, e.g. Motronic.

I don't really want to replace my alternator. They're like $500! A regulator on the other hand is a $60 part. That I can deal with. Regardless, it has to come out for me to replace it. Should I do the brushes at the same time?

I've also heard on this forum that some alternator shops will rebuild your alt for you. Is this an expensive proposition?

[john walker's workshop]

the commutator that the brushes ride on usually is worn pretty bad and it's real thin, so machining is usually not possible. that's the reason most shops generally replace the alt/reg as a unit instead of just hanging a new reg on it. rebuild shops can glue a new comm on the stator though. you possibly could get it rebuilt in the $100 range. or you could see if pelican stocks the PPR brand. they're much cheaper than bosch or valeo, and they are good quality. supposedly they rebuild for porsche.

[Face]

Mark,
I had the same symptoms (along with a non-charging and spiking system voltage) a few weeks back. No idiot light on mine either. Hook a voltmeter up through the cig. lighter (you can buy a cig. lighter insert doohicky from Radio Shack with two leads to hook your voltmeter to). Then you can monitor the voltage with the car running at different RPM's while driving. If you see more than 14-ish Volts, you've got a VR problem.
I ordered a new one from Pelican Parts ($60) and also got a rebuilt alternator from Alternator/Starter Express (on the web) for pretty cheap. However, they did send me a "rebuilt" alternator with a bad VR on it, hence the PP purchase. I pulled the alt. for the second time, put the new VR on and all has been well.
Cheers,

[jmohn]

It does sound like your regulator is failing, causing voltage spikes. This maybe causing more than the usual electrical anomalies if you also have a grounding problem (time to check the straps). I'm a big advocate of rebuilding alternators, a good shop will make it darn near as good as new or honestly tell you they can't. I had mine (on a '78 SC) rebuilt last summer, the cost was about $70 (figure another 50-60 bucks if the commutator's bad); of course on your's you'll also need to spring for a new regulator, but you already know that. I've used the same shop for rebuilding alternators and starting motors for past, almost, 30 years and they've never had to do one more than once (and a couple of their rebuilt units outlasted the OE).

Good luck,

Jerry M
'78 SC

[RazorRacer]

Could you not purchase a cheap voltage regulator at the local auto store and wire it in parallel with the p-car voltage regulator? Then if the problem went away, you would know that it's the voltage regulator.

[autobonrun]

What I'm confused about is why the seat belt warning buzzer and light come on if it's a voltage spike issue. I'm going without looking at a single diagram but I would think a contact switch would cause these events to occur rather than a mere voltage increase.

Obviously during the day, you can't tell anything about the interior lights, however, before I spent any money, I'd try disconnecting the seat belt buzzer and light. Then at night see if the lights still come on bright.

If so, it's definitely a symptom of the voltage increasing, and since they all are increasing, it must be at the source. I'm leaning toward agreeing with the other comments about the regulator however, I would think if the regulator let the voltage increase, the alternator warning light should also come on because the battery voltage would be different from the alternator output. Unless, the first spike took the alternator light bulb out. Does it come on just before cranking as it should?

Keep us posted.

[jmohn]

Originally posted by RazorRacer
Could you not purchase a cheap voltage regulator at the local auto store and wire it in parallel with the p-car voltage regulator? Then if the problem went away, you would know that it's the voltage regulator.

Sorry, it doesn't work that way. A voltage regulator is kind of a voltage sensing switch; in this case putting two regulators in parallel would still allow the failing regulator to excite the alternator and cause voltage spikes.

Jerry M

[RazorRacer]

So the voltage regulator is supposed to sense the battery voltage and when it drops below a certain level, it turns the alternator on???

If that is the case, couldn't our antiquated student disconnect the alternator and see if the problem went away?

[jmohn]

Originally posted by autobonrun
What I'm confused about is why the seat belt warning buzzer and light come on if it's a voltage spike issue. I'm going without looking at a single diagram but I would think a contact switch would cause these events to occur rather than a mere voltage increase.

Obviously during the day, you can't tell anything about the interior lights, however, before I spent any money, I'd try disconnecting the seat belt buzzer and light. Then at night see if the lights still come on bright.

If so, it's definitely a symptom of the voltage increasing, and since they all are increasing, it must be at the source. I'm leaning toward agreeing with the other comments about the regulator however, I would think if the regulator let the voltage increase, the alternator warning light should also come on because the battery voltage would be different from the alternator output. Unless, the first spike took the alternator light bulb out. Does it come on just before cranking as it should?

Keep us posted.

I don't know why the seatbelt buzzer and light come on (nor why it's happening only in 2nd and 3rd gear!); but voltage looking for a ground can do some strange things. I don't think the alternator warning light could be burnt-out or he would get no charge at all. Doesn't the Carrera system depend on continuity at the alternator light for excitation voltage just like the earlier cars? Of course, in a over-voltage situation the alternator light should be coming on as a warning, unless someone (previous owner?) jumpered across it for some unkown reason. I thought the Carrera system used a 4 watt bulb at the alternator light (earlier cars were to install a parallel resistor when they changed to the newer alternator with internal regulator), maybe a previous someone installed a resistor trying to solve a charging problem actually caused by a slowly failing regulator or alternator (or both). It would seem a little sleuthing is required.

Jerry M

[jmohn]

Originally posted by RazorRacer
So the voltage regulator is supposed to sense the battery voltage and when it drops below a certain level, it turns the alternator on???

If that is the case, couldn't our antiquated student disconnect the alternator and see if the problem went away?

In a word - yes. Of course he shouldn't go too far. I think it would be easier to connect up a volt/ohm meter (as previously suggested) and go for a drive.

Jerry M

[RazorRacer]

Originally posted by jmohn


In a word - yes. Of course he shouldn't go too far. I think it would be easier to connect up a volt/ohm meter (as previously suggested) and go for a drive.

Jerry M

That would work, but how do you see the volt/ohm meter while driving the car? Do you bring extension wires around through the window? Not a bad idea if that's it.

[jmohn]

[QUOTE]Originally posted by autobonrun
[B]What I'm confused about is why the seat belt warning buzzer and light come on if it's a voltage spike issue. I'm going without looking at a single diagram but I would think a contact switch would cause these events to occur rather than a mere voltage increase.

-----SNIP-----

As I said earlier, I don't understand this either, but automotive wiring is notorious for odd behavior. A little story - back in my youth I had a '69 Plymouth (Road Runner if anyone knows what they were). You could get in the car, NO key in the ignition, turn on the hazard lights, the left turn signal and step on the brake and the radio would come on. I never figured that one out either.

Jerry M

[rstoll]

I thought I saw an article somewhere about this problem. Bad door switch????