Help diagnosing/making sense of a strange (charging system?) issue - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 13 (permalink) Old 03-19-2019, 08:52 PM Thread Starter
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Help diagnosing/making sense of a strange (charging system?) issue

My 1978 Spider has developed a new feature. After starting the car, pressing the gas pedal causes the "generator" light to illuminate on the dash, more brightly as you press the gas pedal more. This did not prevent the car from driving for the final week of last "season". I first decided this must be a voltage regulator problem and replaced it. This did not fix the problem, and I pulled the car out of the garage to begin spring cleaning to find it has gotten worse. All the lights on the dash will illuminate more brightly when pressing the gas pedal, not just the "generator" light as before, and the problem seems more severe - it was bright enough backing the car out of the garage that I did not want to risk driving her. Now I am struggling with how to diagnose this issue.

In my last test, unfortunately the cheap aftermarket radio I had installed in the dash emitted some smoke and stopped working. I am grateful this was the only breaking to happen, and now this leads me to wonder - does that suggest the voltage put out by the alternator could have exceeded a safe limit? What does that imply since I put in a new external regulator already?

I have used a battery charge monitor to observe the behavior of the charging system at idle (at 1200rpm, it's still cold here) in this video:

Here is what the tachometer looks like when I tap the gas pedal:

I was tempted to go find a replacement alternator and see if that solves the problem, but before I continue replacing parts willy nilly I wanted to run this by the forum to see if that is the best course of action.
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post #2 of 13 (permalink) Old 03-20-2019, 06:07 AM
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The first thing to do is buy a voltmeter so that you can measure the voltage in different places - at the alternator power terminal, at the battery terminals, at the fuse box. It certainly looks like a regulator problem but it could be wiring between the regulator and alternator. A poor connection at the ground braid that connects the bellhousing to the chassis can cause strange things to happen, particularly on cars with separate regulators.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #3 of 13 (permalink) Old 03-22-2019, 01:47 AM
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did you connect new external regulator correctly?
(and yes, an alfa owner needs a decent voltmeter in the tool kit!)
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Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #4 of 13 (permalink) Old 03-24-2019, 09:54 PM Thread Starter
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I did not even think to check the bellhousing ground strap. With the roads near me this is a prudent next step, which I will update on tomorrow. I'm curious how one should ground the voltmeter for these tests, where exactly is the battery grounded to the chassis?

The new regulator connects using the same three pin plug the old one did, so I have no idea if it is the wrong connection. I figured it would be the same as the previous one if the plug wires were oriented the same directions on the new unit.

I will have to probe around and see if there are any problems to be found based on your suggestions!
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post #5 of 13 (permalink) Old 05-05-2019, 09:16 PM Thread Starter
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Latest update after a busy few weeks (unfortunately not Alfa related), I have located the ground strap and verified it is there, at least. I've also discovered poking/pulling on part of the wiring harness under the dashboard causes the dash gauge lights to turn off if they're on when they shouldn't be - starting to look like a damaged wire or connector, of course in the annoying bundled mess of wires.

Can anyone recommend a good source for replacement wire? Guessing I should get a set of spools in every color and stripe+color so I can replace them according to the stock diagram, but how to go about doing this? Order by single spools?
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post #6 of 13 (permalink) Old 05-06-2019, 07:02 AM
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Quote:
Originally Posted by stevespiderguy View Post
In my last test, unfortunately the cheap aftermarket radio I had installed in the dash emitted some smoke and stopped working. I am grateful this was the only breaking to happen, and now this leads me to wonder - does that suggest the voltage put out by the alternator could have exceeded a safe limit? What does that imply since I put in a new external regulator already?
You've probably figured this out already, but yes, it sounds like >> 12v is getting into your electrical system, causing the lights to be extra bright and the radio to fry. Typically this is caused by a bad regulator, so installing a new one was a logical thing to try, but unfortunately, that didn't seem to solve it.

Perhaps it would help us to know what kind of a regulator you installed to replace the old one. Mechanical or solid state? From what source? It isn't impossible that your new replacement was DOA. Does the replacement look like:

Quote:
The new regulator connects using the same three pin plug the old one did, so I have no idea if it is the wrong connection. I figured it would be the same as the previous one if the plug wires were oriented the same directions on the new unit.
Yes, the orientation of the three wires in the plugs shouldn't (*) change between your old and new regulators. However, your problem could be caused by a broken wire at one of the connectors.

The fact that a new regulator didn't make any difference suggests that the old regulator was OK and that some other part of the charging system (like the alternator-regulator harness or bellhousing ground strap) is the issue.

*) I'd say "couldn't change" if I knew for sure that you had installed an OEM-type regulator.

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I've also discovered poking/pulling on part of the wiring harness under the dashboard causes the dash gauge lights to turn off if they're on when they shouldn't be
I suspect that is a separate, more minor problem than the over-voltage. Probably just a worn/flakey connector. I'd concentrate on why the charging system is putting out too much voltage, and get back to the intermittent dash lights later.

Jay Mackro
San Juan Capistrano, CA

'65 Guilia Sprint GT
'67 Duetto
'91 164L

Last edited by Alfajay; 05-06-2019 at 07:14 AM.
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post #7 of 13 (permalink) Old 05-07-2019, 06:34 PM
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Attached at the left lower section of the dash there is a cluster of ground wires. see if they're tight, but as routine maintenance, I would remove, clean, polish, and reinstall them tightly.

It's likely voltage is looking for a ground and is using other components to achieve that.

It's Giuseppe's giubos, not Guido's guibos, on my 78 Alfas
REFRESH CONNECTIONS BEFORE REPLACING COMPONENTS
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post #8 of 13 (permalink) Old 05-07-2019, 06:58 PM
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Might be worthwhile to remove the dash and go in and clean and tighten all the wire connections. I did that about 10 years ago. The dashboard on a Spider actually comes off fairly easily. After that, it's easy access to everything. I doubt seriously that you need to rewire. Keep in mind that convertibles get wet inside and that moisture evaporates up under the dash corroding connections.

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post #9 of 13 (permalink) Old 05-19-2019, 07:59 PM Thread Starter
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OK folks, I have you to thank for keeping me grounded in this endeavour. I located the ground connection on the left side under the dash and made sure it was a clean connection. By the way, under the dash there are a few wires going nowhere and one of them is connected to these two white boxes next to the steering column which don't appear to be used for anything - any idea what these are?

I pulled the radio out and discovered indeed, the supply bypass cap has been blown clean off. I also checked the battery voltage with a multimeter while a friend tapped the gas pedal and watched the voltage jump. OK, getting somewhere. So I definitely suspect either the regulator or the alternator is faulty. The regulator in the car previously, installed by the previous owner, was a small box I am guessing was solid state. Picture of the underside attached, and I think this item on eBay is a "universal Bosch regulator" of a similar variety. The regulator I replaced it with was a Beru 90160320602, like this one on eBay, and saw no change. Granted that replacement is something I bought some three years ago and never tested, so maybe it's DOA? Would you recommend I get another one, and if so is there a preferred regulator for these cars?

How could I test the alternator? Can I get a rebuild kit or at least replace the brushes? I have no idea when it was serviced or repaired.
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Last edited by stevespiderguy; 05-19-2019 at 08:01 PM. Reason: Forgot to attach pictures.
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post #10 of 13 (permalink) Old 05-21-2019, 03:07 AM
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those two white boxes look like the key buzzer and seat belt buzzer.

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #11 of 13 (permalink) Old 05-21-2019, 09:17 PM Thread Starter
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Good to know spiderserie4, this is the second time a previous owner has made such a modification to an Alfa before me. This time whoever it was must not have seen fit to remove the buzzers, just the wires.

General update, I have dug into the spider workshop manual and now believe it may be time to set aside my desire to know what is wrong with the alternator, and instead just try replacing it. I have not replaced it since buying the car anyway, so who knows. I can't see any record from the previous owner of having done such a replacement which accounts for 10-20 years so it may be the original.
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post #12 of 13 (permalink) Old 05-21-2019, 09:30 PM
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those two white boxes look like the key buzzer and seat belt buzzer....
...so it makes sense that a P.O. pulled the wires going to them (nobody likes listening to those silly things). This is a perfectly reasonable modification, and wouldn't cause any of your symptoms.

Quote:
Originally Posted by stevespiderguy
now believe it may be time to set aside my desire to know what is wrong with the alternator, and instead just try replacing it.
Not sure I would recommend replacing the alternator without knowing what the problem is. A bad alternator typically produces low or no voltage, but you are getting too much. It usually takes a bad regulator to result in that. So your first reaction - changing the regulator - made sense, but unfortunately didn't work.

My advice would be to take the alternator AND regulator to your local automotive electrical shop and ask them to test them. In the event that the alternator is bad, these shops can rebuild them. Others have reported that chain stores like Autozone can test alternator-regulators, though I have no experience with this.

Jay Mackro
San Juan Capistrano, CA

'65 Guilia Sprint GT
'67 Duetto
'91 164L

Last edited by Alfajay; 05-21-2019 at 09:46 PM.
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post #13 of 13 (permalink) Old 07-01-2019, 06:30 AM Thread Starter
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I called around to some stores and could not find any place in my area willing to test an alternator - strange! I now have two spare alternators and regulators which are likely faulty. Whatever the case may be, with my BNR parts alternator from eBay, the car runs like new. I am in complete agreement I probably should have taken your advice and tested the alternator I had first, but I was itching to drive the car this summer and it was well worth the peace of mind.

With a new alternator, the car runs like new. And the new alternator is a high output (80A, believable?) rebuilt version of the milano alternator from the early 80s. No complaints being able to drive the car. On to the next repair I'm sure. Thanks all for your advice here.
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