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Discussion Starter #1
Good evening! I have a 1980 Volkswagon Rabbit (Diesel).

ISSUE:
Battery dies within a day or two after a full charge.

BACKGROUND:
For a few weeks now, I noticed the battery light come on but illuminate like a dancing strobe light. Seemed to be intermittent when it came on. Sometimes it'd be only in lower gears, other times it'd be cruising down the interstate. I checked to see if the alternator belt came loose but it wasn't. So, I ignored the light for awhile until one day it wouldn't start. The starter would just click (very fast) after turning the key.

I assumed my battery was going bad (already on my second replacement in 6 months from AutoZone), my grounds came loose (recently replaced them), or the alternator failed.

MY REPAIR ATTEMPTS:
1. Recharge the battery and get it tested.
Battery tested good. Worked for a few days before it completely drained again. Had it jumped and the engine turned-over no problem.

2. Recharge the battery and get it tested again.
Battery tested good.

3. Remove the alternator and get it tested on a bench.
Alternator tested good at 40A? Can't remember if he said 40 or 60—but it passed.

4. Reinstall everything and clean-up all ground connections (recently replaced 4 months ago)

5. Conduct a parasitic drain test according to the YouTube video shared in other threads.
No drain evident even in the 200mA mode.

6. Start the car. Check the voltage of the positive terminal on the battery after jumping the negative terminal on the battery to the alternator bracket and pressing the accelerator past 100RPM to active battery charging.
13.4V confirmed. Battery light never flickered.

7. Turn-on blower to HIGH and set heat to MAX. Check the voltage of the positive terminal on the battery again.
13.3V confirmed. Battery light never flickered.

8. Turn-on blower to HIGH and set heat to MAX. Turn on headlights. Check the voltage of the positive terminal on the battery again.
13.2V confirmed. Battery light never flickered.

9. Drive the car 30min on the interstate. Turn off engine. Check battery voltage.
12.6V confirmed. Battery light never flickered.

10. Check battery voltage again after 30min.
12.6V confirmed.

11. Monitor battery light while driving 30min.
Flickered during drive like a strobe light again.

CURRENT STATUS:
Car is running fine but I fear the battery will fail again. Will continue to monitor voltage. Any suggestions on what I should do next? Seems the alternator is charging the battery, although I'm not getting the 13.74-14V range Briano has stated in other posts that I should be expecting.

Thanks for your help.
 

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You sir have a problem with the blue wire that feeds the light on the dash and gets the battery charged. You may also have a bad voltage regulator but since the alternator tested good that is a small possibility. Check the big plug that goes into the alternator and wiggle those wires round and round with an ohm meter connected to the tab inside the plug. It could be that the wire is cracked or broken at the terminal connection and you are not getting voltage to the battery all the time or that the blue wire is intermittently connecting.

I had a heck of a time finding the fray in my blue wire at the very end of the terminal connection. I ended up taking a stiff piece of copper wire and clipping the ends real sharp and poking it into the rubber part next to the terminal end and then jamming the blue wire down on top of that. Then taping it all tight. Have not had a voltage problem since.

The age of the car and the weathering of wire insulation in all kinds of climate makes it brittle. You may be better off replacing the whole wire from dash to alternator just to make it all new and remove the possibility of other cracks making voltage connections possible.
 

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Highest suspects Voltage Regulator, you should be pushing 55Amps on a Alternator not 40.
I have gotten once 4 bad alternators on one of my cars before I got a good one.
The Blue exciter wire feeds the coils in the Alternator to give you a field that allows the alternator to start charging.
If that Exciter is wonky then you can loss the Field, and when the alternator gets hot your regulator can go bad as in over heating and stop working
which is why you are seeing a flickering Battery lamp. That indicates that your Alternator isn't charging fully and that the car is running off the battery.
13.2V is low for an alternator as well it should be 13.5-13.8....

I think you are looking at a new alternator or voltage regulator.

As Oregon stated those plugs are over 35 years old... So look at them closely....but I think it is your VR or Alternator.
 
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Discussion Starter #4
Thank you so much for your help! I think I'll start with the blue exciter wire only because it'd be the easiest & cheapest fix. If that doesn't work, I'll look for a new regulator for the alternator. Concern is, however, the previous owner put in a different alternator than the original (brand new when I purchased 2 years ago). Not even sure what it is but he made a custom bracket for it.

 

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Not even sure what it is but he made a custom bracket for it.

Well they say a picture is worth a thousand words but this one sorta leaves me speechless. This Rube Goldberg set up really has me wondering on a couple of things. Proper alternator output at all. Is a 55 or 90 amp output? Probably not, more like the 40 you are measuring which is too low.
The hose clamp does what? Since there is no hose there I am left holding my chin. And the cable with the clamp? Spare parts from a garage door install some place?

If I were trying to fix this problem I would be looking for the proper bracket and alternator for this vehicle. I can look in my spare parts bin and see if I have one. The alternator is easier to find than the bracket actually.

Still go ahead and check that blue wire, I think it is probably the culprit but a new voltage regulator may be as expensive as a known used 55 amp alternator off Craigslist.

Let us know if you get it solved. :confused:
 

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Discussion Starter #6
Haha!! this made me laugh hysterically.

Sorry, I should have explained...

Yeah, it's a mess! The hose clamp and cable was my MacGuyvered way to keep the alternator plug in place. The hose clamp holds both ends of the cable on either side of the alternator to secure the plug (the metal clip that would normally keep it in place is missing).

I suspect the last owner made this bracket to use a higher output alternator. It's the only reason I can think of. Yeah, if you have the bracket, I'd definitely be interested! Is it typical to use a higher output alternator on our Rabbits? Otherwise, I'm going to have to find the same type of alternator he used.

Went ahead and replaced the blue exciter wire. I'll advise how it goes after driving it around a few days and monitoring the battery voltage.

Thanks for your help!

Well they say a picture is worth a thousand words but this one sorta leaves me speechless. This Rube Goldberg set up really has me wondering on a couple of things. Proper alternator output at all. Is a 55 or 90 amp output? Probably not, more like the 40 you are measuring which is too low.
The hose clamp does what? Since there is no hose there I am left holding my chin. And the cable with the clamp? Spare parts from a garage door install some place?

If I were trying to fix this problem I would be looking for the proper bracket and alternator for this vehicle. I can look in my spare parts bin and see if I have one. The alternator is easier to find than the bracket actually.

Still go ahead and check that blue wire, I think it is probably the culprit but a new voltage regulator may be as expensive as a known used 55 amp alternator off Craigslist.

Let us know if you get it solved. :confused:
 

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Well rsbidinger, I checked on the bracket and I think it is one left over from my sons Dasher. Engine mounts longways in that one. So the bracket I have accepts an alternator but the adjustment bracket I have is too short to connect to the two of them. I am not sure the bolts holding the bracket to the engine would be the same either.

But fear not. Craigslist in Portland has some MK1 parts for sale and if you go to this link:

https://portland.craigslist.org/wsc/pts/d/hillsboro-vw-mk1-mk2-rabbit-jetta-parts/6941200274.html

And look in the box with pulleys and brackets you see a long adjustment type bracket. I think the one that holds the alternator is there too but you should just ask if it is there. He may ship you them both for a good price. That is the fall back on my fall down. Sorry to get the hopes up.
Oh and the alternator thing, When VW went to putting A/C on their cars that is when they upped the amps from a 55 amp to a 90. Putting a better/higher rated alternator on your car might help a bunch if you are pulling a lot of amps into a sound system of lights. I put a standard one on mine a bit ago as I don't have need for a big draw or demand. I barely run the heater motor. Just the wipers and lights.

Best of luck on this. Going back to proper equipment can only be a good thing in my opinion.
 

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Oh and the alternator thing, When VW went to putting A/C on their cars that is when they upped the amps from a 55 amp to a 90. Putting a better/higher rated alternator on your car might help a bunch if you are pulling a lot of amps into a sound system of lights. I put a standard one on mine a bit ago as I don't have need for a big draw or demand. I barely run the heater motor. Just the wipers and lights.

No they went to the 90Amp when they added, and an electric motor for powered tops in the 86 Cabriolet, then in the 90s they added electric windows, and a larger stereo for them as well.

in the 80-84 they had the standards 50-55 amp alternators, but that being said if you are running high amp Stereos, or a sub then you may want the additional current.
but for Stock 81-84 with 1.5 or 1.6 Diesels with a/c they had the 50-55A.
 
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Discussion Starter #9
No problem thanks for the link. Portland is where I originally bought my Rabbit!

Yeah, I'm not running any auxiliary equipment and the previous owner didn't look like he ran anything either—which again makes me wonder why he installed this alternator.

Nevertheless, I'll look into buying a new bracket and installing the proper alternator after confirming the replacement exciter wire doesn't fix my problem. I mean, I think more power is better for when I do install something auxiliary later down the road (aftermarket radio or something), but I can't find any markings on this alternator and I'd have to find one just like it to use the custom bracket.

Thanks ORCoaster!

Well rsbidinger, I checked on the bracket and I think it is one left over from my sons Dasher. Engine mounts longways in that one. So the bracket I have accepts an alternator but the adjustment bracket I have is too short to connect to the two of them. I am not sure the bolts holding the bracket to the engine would be the same either.

But fear not. Craigslist in Portland has some MK1 parts for sale and if you go to this link:

https://portland.craigslist.org/wsc/pts/d/hillsboro-vw-mk1-mk2-rabbit-jetta-parts/6941200274.html

And look in the box with pulleys and brackets you see a long adjustment type bracket. I think the one that holds the alternator is there too but you should just ask if it is there. He may ship you them both for a good price. That is the fall back on my fall down. Sorry to get the hopes up.
Oh and the alternator thing, When VW went to putting A/C on their cars that is when they upped the amps from a 55 amp to a 90. Putting a better/higher rated alternator on your car might help a bunch if you are pulling a lot of amps into a sound system of lights. I put a standard one on mine a bit ago as I don't have need for a big draw or demand. I barely run the heater motor. Just the wipers and lights.

Best of luck on this. Going back to proper equipment can only be a good thing in my opinion.
 

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Discussion Starter #10
I wonder if the 90A units were the same size without any modifications required to fit the 1.6 Diesels...

I'll have to look into this. If I need a new alternator, may be worth to upgrade now.

No they went to the 90Amp when they added, and an electric motor for powered tops in the 86 Cabriolet, then in the 90s they added electric windows, and a larger stereo for them as well.

in the 80-84 they had the standards 50-55 amp alternators, but that being said if you are running high amp Stereos, or a sub then you may want the additional current.
but for Stock 81-84 with 1.5 or 1.6 Diesels with a/c they had the 50-55A.
 

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The issue with all alternators is that there were 2 styles of them over the years, and 3 different ways to mount them depending on the options that you had as there were 2 types of a/c compressors that were used.

The First type was the "Motorola" Plugged Alternator for the US Market. My 81 was a combination of things. The Body (Westy) was mage in the US. The engine and transmission were assembled in Germany with every thing plug and play, that was the engine Alternator, A/C (sanden) were all put on the engine in Germany, and shipped over as a Unit to be installed on the assembly line.
The motorola plug had a 90 degree angle bracket that was held in place by a 8mm bolt or stud to keep the plug in the alternator tight, which is why you have the workaround :) as your bracket is missing.

This had a 4 bolt A/C mount and the Compressor was under the Alternator (as the latter Cabbies were) the Alternator was denoted as a "motorola plug type" and when I was looking at a bad alternator I was asked if it had a/c if the answer was yes, then the alternator came with a shorter pulley.

The Second a/c type was the York compressor that mounted on top of the alternator, and it too had a shorter pulley....was hard to replace and a pain in the posterior to work around.

The third type was a Motorola with no a/c. It mounted to the mounting point of the A/C compressor bracket and had a pulley that was longer. It mounted on top and had a different bracket to position it.

A/C brackets also had 3 iterations over the years, that is one that used 2 bolts and you had to Pry it tight, the Star adjuster that was also a royal pain, and lastly the 84-87 used one that had a barrel bolt design that you could loosen the pinch bolts and tighten it to the proper belt tension, and it would hold itself there while you tightened the other bolts...It was far superior than any thing going, why they changed for the Star gear adjuster is beyond the scope of normal engineering by accountants...

The Motorola alternator came in a generic variety that is 55A was the most I have seen, but you could get a 90 Amp Motorola from a Automotive electric, or a remanned one...uncommon for the 80's but I know I had that option.

The German's or Euro Markets used a Bosch Alternator it didn't have a plug, but two Studs for connections, they used it for the Cabriolets as they were German Built at Karmann. They came in with 55amp and 90 versions in the latter Cabriolets you can also have them rebuilt for 120Amp or buy new 120amp at the time. Most of the alternators that I see now are re-manned....

So if you are going to see the mounting differences you need to peruse the ETKA, and most of the mounts are under the engine part, and not the Electrical as you would think.

https://volkswagen.7zap.com/en/usa/

There is also the Euro styles RHD that may have better pictures.

https://volkswagen.7zap.com/en/rdw/

and of course the Cabriolet.
 
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Discussion Starter #12
Fantastic information. Thank you Braino. This will definitely help.

After a week of driving with the exciter wire replaced, it appears my problem is solved. No more dancing battery light and the voltage has remained constant. Woohoo!

Thank you everyone for your help. So glad it was a simple fix. Think it would've been a long time before I suspected this being the culprit!

The issue with all alternators is that there were 2 styles of them over the years, and 3 different ways to mount them depending on the options that you had as there were 2 types of a/c compressors that were used.

The First type was the "Motorola" Plugged Alternator for the US Market. My 81 was a combination of things. The Body (Westy) was mage in the US. The engine and transmission were assembled in Germany with every thing plug and play, that was the engine Alternator, A/C (sanden) were all put on the engine in Germany, and shipped over as a Unit to be installed on the assembly line.
The motorola plug had a 90 degree angle bracket that was held in place by a 8mm bolt or stud to keep the plug in the alternator tight, which is why you have the workaround :) as your bracket is missing.

This had a 4 bolt A/C mount and the Compressor was under the Alternator (as the latter Cabbies were) the Alternator was denoted as a "motorola plug type" and when I was looking at a bad alternator I was asked if it had a/c if the answer was yes, then the alternator came with a shorter pulley.

The Second a/c type was the York compressor that mounted on top of the alternator, and it too had a shorter pulley....was hard to replace and a pain in the posterior to work around.

The third type was a Motorola with no a/c. It mounted to the mounting point of the A/C compressor bracket and had a pulley that was longer. It mounted on top and had a different bracket to position it.

A/C brackets also had 3 iterations over the years, that is one that used 2 bolts and you had to Pry it tight, the Star adjuster that was also a royal pain, and lastly the 84-87 used one that had a barrel bolt design that you could loosen the pinch bolts and tighten it to the proper belt tension, and it would hold itself there while you tightened the other bolts...It was far superior than any thing going, why they changed for the Star gear adjuster is beyond the scope of normal engineering by accountants...

The Motorola alternator came in a generic variety that is 55A was the most I have seen, but you could get a 90 Amp Motorola from a Automotive electric, or a remanned one...uncommon for the 80's but I know I had that option.

The German's or Euro Markets used a Bosch Alternator it didn't have a plug, but two Studs for connections, they used it for the Cabriolets as they were German Built at Karmann. They came in with 55amp and 90 versions in the latter Cabriolets you can also have them rebuilt for 120Amp or buy new 120amp at the time. Most of the alternators that I see now are re-manned....

So if you are going to see the mounting differences you need to peruse the ETKA, and most of the mounts are under the engine part, and not the Electrical as you would think.

https://volkswagen.7zap.com/en/usa/

There is also the Euro styles RHD that may have better pictures.

https://volkswagen.7zap.com/en/rdw/

and of course the Cabriolet.
 

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Glad you got to hit the EASY button. I hardly ever get that to work for me. But then if it was always easy to fix I wouldn't spend days in the driveway disturbing the neighbors. Nor would I know what I know, like that blue wire problem. Mine stumped me for a couple days as I would get it to work and then wiggle on the wire and it wouldn't. Finally had to poke a pin in the wire about a foot away from the plug and connect the ohm meter to the spade and wiggle it. Ahh, so there is a problem between here and there. Got it taken apart and could see the reason for that intermittent connection and solved it by joining with a stiff wire. I too have no longer seen the dreaded red light come on while driving.
 
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