After start, will not charge until revved past 3k RPM

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nabeelr
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After start, will not charge until revved past 3k RPM

Post by nabeelr »

Sorry, I posted this in the wrong place, Here it is in the proper place:
viewtopic.php?f=7&t=3059&p=26769#p26769

Moderator note: Topics have been merged.



Hi all!

I'm having an issue where, sometimes, after a start, my alternator will not start charging the battery until the engine is revved past 3000RPM.
No alternator warning light or anything, but also no charging.

The moment the Tach gets above 3k RPM, you can see the voltage gauge jump up, and the alternator will start charging the battery.

This may be a separate issue, but it seems that when this happens, the alternator light will never come on, even when the key is turned to "ON" without being started. It's not a bad bulb in the dash cluster, that I know.


They may be two separate issues, or one and the same, I don't know, but it seems that when I don't see the alternator check light come on before a start, that after a start the alternator will not charge until revved past 3k RPM.


Any ideas?


Thanks!
Last edited by nabeelr on Tue Aug 13, 2013 10:30 am, edited 1 time in total.
nabeelr
Posts: 15
Joined: Tue Jul 30, 2013 6:09 am
What year is your cabby?: 1988
Do you own a Cabriolet?: Yes
Location: Ottawa, Ontario, Canada
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After start, will not charge until revved past 3k RPM

Post by nabeelr »

(I originally posted this in the General section, then realized that there is a better place for it, Sorry...)

Hi all!

I'm having an issue where, sometimes, after a start, my alternator will not start charging the battery until the engine is revved past 3000RPM.
No alternator warning light or anything, but also no charging.

The moment the Tach gets above 3k RPM, you can see the voltage gauge jump up, and the alternator will start charging the battery.

This may be a separate issue, but it seems that when this happens, the alternator light will never come on, even when the key is turned to "ON" without being started. It's not a bad bulb in the dash cluster, that I know.


They may be two separate issues, or one and the same, I don't know, but it seems that when I don't see the alternator check light come on before a start, that after a start the alternator will not charge until revved past 3k RPM.


Any ideas?


Thanks!
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Briano1234
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Re: After start, will not charge until revved past 3k RPM

Post by Briano1234 »

nabeelr wrote:(I originally posted this in the General section, then realized that there is a better place for it, Sorry...)

Hi all!

I'm having an issue where, sometimes, after a start, my alternator will not start charging the battery until the engine is revved past 3000RPM.
No alternator warning light or anything, but also no charging.

The moment the Tach gets above 3k RPM, you can see the voltage gauge jump up, and the alternator will start charging the battery.

This may be a separate issue, but it seems that when this happens, the alternator light will never come on, even when the key is turned to "ON" without being started. It's not a bad bulb in the dash cluster, that I know.


They may be two separate issues, or one and the same, I don't know, but it seems that when I don't see the alternator check light come on before a start, that after a start the alternator will not charge until revved past 3k RPM.


Any ideas?


Thanks!
Cool as i will answer here.

Disconnect the battery ground.
On the back of the alternator is the voltage regulator. Held in by 2 Phillips screws.
Take it out and carefully.

Now in that hole you will see come copper brushes that have a black line between them.
using a straight pin (not that there are Gay pins that I know of) scrape the black stuff out a bit between the pads.
Now for the pads themselves, use a pencil eraser to "shine" them back up... then again clean out between the pads.

The voltage regulator is a sealed unit, but you can expand the holes so that you can get more down pressure.
Reinstall it,
Replace and tighten the ground.
Re-tighten the belt.

Give it a go.

If it is still acting the ass, then I would look at replacing the alternator....
You can go to a wrecking yard and see if you can find a voltage regulator as that is probably the thing that is wrong. But the difference in price isn't that much.

But I usually go to a wrecking yard and get a alternator, then have it tested at Autozone, if it works, cool if not Tale it back to the yard and get another.... then go have it tested again, (at pepboys).... I have a whole bunch of places to get parts that test for free.

Oh and replace your grounds battery to frame and frame to engine/tranny.
Briano

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You can lead a user to a link, but you can't make him Click.... :screwy:
nabeelr
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Re: After start, will not charge until revved past 3k RPM

Post by nabeelr »

I will try that.

I should point out that once I blip it past 3K RPM, it will continue charging even below at idle @ 900RPM.

Does that make a difference in your assessment?


Thanks again!
CalAltaDubber
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Re: After start, will not charge until revved past 3k RPM

Post by CalAltaDubber »

nabeelr wrote:Hi all!

I'm having an issue where, sometimes, after a start, my alternator will not start charging the battery until the engine is revved past 3000RPM.
No alternator warning light or anything, but also no charging.

The moment the Tach gets above 3k RPM, you can see the voltage gauge jump up, and the alternator will start charging the battery.
This is pretty normal, although it is not supposed to happen, it does. for some reason, when the car is started the alternator/voltage regulator just don't seem to "kick in" like it should until it is reved.

I have even seen this happen on jet aircraft (CF-104 to be precise), so it's nothing to worry about.

As long as the alternator is charging there is nothing to worry about. You might check the voltage regulator. It is on the back of the alternator and held on by two screws. Measure the two brushes. If they are less than 5 mm long, the voltage regulator needs to be replaced.
nabeelr wrote:This may be a separate issue, but it seems that when this happens, the alternator light will never come on, even when the key is turned to "ON" without being started. It's not a bad bulb in the dash cluster, that I know.


They may be two separate issues, or one and the same, I don't know, but it seems that when I don't see the alternator check light come on before a start, that after a start the alternator will not charge until revved past 3k RPM.


Any ideas?


Thanks!
I believe this is a seperate issue. The battery warning light should be flashing when the key is in the ON position and the engine is not running.

What year is your car? I can do a little research to see if I can find anything.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
'04 Golf
'12 Golf Wagon TDI
'69 Manx type Dune Buggy (New Toy)

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nabeelr
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Re: After start, will not charge until revved past 3k RPM

Post by nabeelr »

Yeah, I guess these kind of specifics would be useful.

It's an 88 Cabriolet, Manual.
CalAltaDubber
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Re: After start, will not charge until revved past 3k RPM

Post by CalAltaDubber »

nabeelr wrote:I will try that.

I should point out that once I blip it past 3K RPM, it will continue charging even below at idle @ 900RPM.

Does that make a difference in your assessment?


Thanks again!
No that sounds pretty normal.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
'04 Golf
'12 Golf Wagon TDI
'69 Manx type Dune Buggy (New Toy)

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CalAltaDubber
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Re: After start, will not charge until revved past 3k RPM

Post by CalAltaDubber »

nabeelr wrote:Yeah, I guess these kind of specifics would be useful.

It's an 88 Cabriolet, Manual.
Good, One of my cars is an '88, I'll do a little research tonight.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
'04 Golf
'12 Golf Wagon TDI
'69 Manx type Dune Buggy (New Toy)

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nabeelr
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Re: After start, will not charge until revved past 3k RPM

Post by nabeelr »

To answer your question on my other post,
It's an 88 Cabriolet, Manual.

Thanks for all your guys' help by the way, much appreciated.
CalAltaDubber
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Re: After start, will not charge until revved past 3k RPM

Post by CalAltaDubber »

No problem.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
'04 Golf
'12 Golf Wagon TDI
'69 Manx type Dune Buggy (New Toy)

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nabeelr
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Re: After start, will not charge until revved past 3k RPM

Post by nabeelr »

So, as far as the alternator bulb never coming on, that may just be a wiring issue?
CalAltaDubber
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Re: After start, will not charge until revved past 3k RPM

Post by CalAltaDubber »

That's what I will look into tonight.

I will check the wiring diagram and confirm with my car.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
'04 Golf
'12 Golf Wagon TDI
'69 Manx type Dune Buggy (New Toy)

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Re: After start, will not charge until revved past 3k RPM

Post by nabeelr »

Oh that's awesome, thanks!
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Re: After start, will not charge until revved past 3k RPM

Post by kamzcab86 »

The two topics have been merged (hence some repetition). In the future, simply PM a moderator; we'll move the topic for you. :beer:
CalAltaDubber wrote: I believe this is a seperate issue. The battery warning light should be flashing when the key is in the ON position and the engine is not running.
I disagree; I think the problems are directly related (car's year doesn't matter; all 1980-1993 Cabriolets operate in the same manner when it comes to charging). Current from the battery to the alternator is routed through the charging system warning light in the instrument cluster via a blue exciter wire (make certain this entire circuit has no faults: no breaks in the wire, connected properly at all points, etc.). Once the alternator's output equals the battery's voltage, the warning light goes out, indicating that the alternator is now charging the battery. If the light is not illuminated even at ON, there is a problem: bulb is blown (how did you verify that the bulb is still good?), faulty wiring, etc. Having to rev the engine up past 3000 rpm + the indicator light being out, indicates that the exciter circuit is faulty in some way.

The charging light is a steady-on light; it does not blink when the key is turned. You're thinking of the oil pressure light. :wink:
CalAltaDubber
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Re: After start, will not charge until revved past 3k RPM

Post by CalAltaDubber »

Actually the year of the vehicle does matter, as we are aware, there are different wiring diagrams for diferent model years. Even though the charging system operates the same, there may be suttle wiring diferences. Therefore to make sure the correct data is used, the correct diagrams for the car must be used.

Secondly, yes the temp. light is the one that flashes (I stand corrected), but the battery light should be illuminated when the key is in the ON position and the engine is not running. Simply because the alternator is not turning and not charging the battery. If you were to stall out your car, the battery light should illuminate for the very same reason.

Like I said, I am going to research the circuit and confirm it on my cars (both known servicable), since the '87 and '88 use the same diagrams, they should both be the same.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
'04 Golf
'12 Golf Wagon TDI
'69 Manx type Dune Buggy (New Toy)

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