no charge... at a loss

[greg lousy]

The golf started losing electric power, especially when driving at night. At first, when I was really running low and dark, the idiot light would fade on at high RPMs. I noticed my WP/AC/ crank pulley belt was very loose, so I thought the belt was slipping at high RPMs- readjusted tension for both V belts, but still the same power loss - at night at least. Connections and grounds looked OK (I've got extra grounds too). At first, it looked OK with a multimeter - the battery was at about 12.5 and would jump up to near 14 (too much?) when the car was running. But.... still losing power.. driving in dark, needing jumpstarts, etc. Idiot light still appeared functional
Upon more testing, I found that with the lights on, the voltage would slowly drop - not the one time drop and hold steady I was expecting. My alternator started to whistle pretty loud a few months ago, and I was suspect of it anyway, so I swapped it with the jetta's (which is a work in progress)
Now I've got no rise in voltage when the car is running - the voltage climbs slowly in idle, drops when revved (normal? - this happenned with both alternators), and definitely does not have the voltage spike you want to see when the alternator starts spinning. So I checked the wiring, redid the main ground connection, cleaned my other grounds, (Oh, I had replaced the terminal clamps too in the beginning of this mess), cleaned the connectors for the main wire to the alt (at the alt and at the starter). Then I followed the exciter (idiot light) wire. I found and replaced a pretty bad looking connection
.... all, of course, to no avail. The warning light goes on with the key in "run" and the motor off, just like it should, but now its not coming even when the car is so dead that I'm worrying about the stop solenoid clicking shut. Its still a suspect for me, but I don't know what else to do about it now that I've traced it to the firewall, and know that it is basically connected.

I've also tried bypassing the starter with a wire right from the alt to the battery, and running a ground from the alt housing, each with no apparent effect. I've also tried both of my voltage regulators in the current alternator (notice the increase in desperation)

Not sure where to go next.
I have a mk 1 bentley and a mk2 car, so no wiring diagram.... and no test equipment other than my multimeter.
Could I run the exciter wire to the battery and bypass the warning light? at least for testing? It looks like the alternator thinks its charging when it isn't. Or I have two bad alternators. Or something else... I understand this system basically, but not much more
... open to ideas.

[bscutt]

If you have a local auto parts store that tests alternators I would take one or both to them and have them tested. At least eliminate that possibility. If they test good under load, I suppose you could try the exciter wire direct to the battery. Are you sure the main power wiring from alternator to battery is good? Maybe try rigging a jumper to bypass that and see if there's any difference? Also check battery cables for corrosion and such. You could also look for voltage drops between points like alternator output to battery positive, alternator housing to negative battery terminal, and so on. First and foremost is verifying alternators are good though. Also worth pulling the battery and have it load tested too. I have had cells short internally and teh battery will charge to full voltage but will then quickly drop back to 5 cells worth (like 10.5 volts).

[82vdub]

I would have the alternator(s) tested and battery tested like bscutt mentioned first to know where you start. Hope that it's just two bad alternators, or a bad battery that wont hold a good charge or something.

I wouldn't run the exciter wire to the battery. This is an intermittant connection and I believe will burn something up if it's connected to 12V constantly.

BTW, you can also buy a one wire voltage regulator for these vehicles and install that in an alternator. This removes the signal that comes through the diode alt light in the dash, if you suspect that this wiring could be an issue.

[greg lousy]

could just a bad battery cause such a blackout with the car running?
I forgot to mention that I switched the battery with the jetta's when this looked like just a starting issue.

I will probably get the alternators tested, but the more I poke around, the more I think they're both good, or at least they act exactly the same and basically produce power. With both alt's, I'm getting close to 14 volts with accessories off (lights, blower, defrost). This drops about .5 volts when the engine is revved to about "running" RPM"s. With the lights on, the pattern is the same but the voltage drops, and with the blower on too, it gets me under 12, and things really start to fade. Warning light fades on in a way that seems appropriate when things get like that.

Today I added a ground from Alt housing... no difference. I also (briefly) jumpered a thin gauge wire to the exciter terminal from battery when the voltage dipped below 12 with no difference. I also checked for voltage drops around the main Alt/ battery wire and it checked out fine. I had already cleaned/ checked main grounds. I'm now fairly convinced that the exciter wire and the main wiring to the Alt. is good.

I realize I'm being a little backwards by doing all this without first getting the Alts tested. I've been doing what I can while working, not having another car, and hoping to drive a few hours to visit relatives on Saturday.
Probably test Alt's next week. Could load reduction relay failure look like this?

[TylerDurden]

...I also (briefly) jumpered a thin gauge wire to the exciter terminal from battery when the voltage dipped below 12 with no difference. I also checked for voltage drops around the main Alt/ battery wire and it checked out fine. I had already cleaned/ checked main grounds. I'm now fairly convinced that the exciter wire and the main wiring to the Alt. is good.

This should result in proper charging, particularly directly exciting the field.

I'd get the battery and the alternator(s) tested.

[Fatmobile]

See if the blue wire has power.
There's a good chance the connector under the battery is corroded.
Lift the battery, find the connector in the blue wire, replace it with a solder and heat shrink.

[greg lousy]

I've got power at exciter terminal when the car is off and in the "run" position... wasn't able to check during the start up process. Also the warning light function appears correct. Earlier, I had I traced the blue wire and found that it, and some other wires were connected not under the battery, but in a bundle of electrical tape with really bad looking crimp connections (including the stop solenoid wire... !). I replaced the connection and thought "well, that was probably it" for about the third time in this process. I'm fairly confident that the charging circuits are fine.

I'm buying a new battery and driving to my hometown tomorrow, from what I've seen in testing I should be OK with no lights and blower. Worst comes to worse, I'll have two trickle charged batteries in the back. Yes, probably ill advised, but my brother's around once a year. When I get back I'll start getting the batteries and alternators properly tested and start from there again.

[82vdub]

After the regulator came loose from the back of the alternator and the car overcharged the battery on a trip back from Texas, we got a new battery and we drove our 82 Rabbit from St. Louis, MO to Green Bay, WI over the course of two days on just the battery. No headlights, no radio, nothing that would use juice, and it made it just fine. I've even removed the alternator to have it rebuilt and used the car to go to work and back for over a week by charging the battery at night.

If all else fails, you can remove the fuel solenoid and take out the plunger and spring and these cars won't pull any current to operate the engine at all. Stopping the car is another thing, but you could literally drive these cars across the country on just the battery to start the car and run the brake lights if you needed to.

[greg lousy]

Thank you, I appreciate that. That will bring my blood pressure down a few points tomorrow, especially since it looks like I may have to run the wipers.
(.... or pick up some rain X...... hmmmm)

[greg lousy]

I made the trip fine. I bought a new battery, but I used the existing one, with a fresh charge from a charger and kept the new one in back... just to further test things out. It made the trip fine, then the whole charging system continued to appear normal (to me anyhow).... I've run with the lights, blower, etc. I've now put in the new battery and got the old one tested. It tested good. I also had the current (the second, swapped in) alternator tested, (in - car only) and it tested fine.
I plan on testing the original alternator and figure out exactly what happened ... showed up to get it bench tested but I seemed to have misplaced the regulator.
One mistake I was making was that when I was testing, and having the real bad issues (lights going out, etc.) I was using my battery charger way too tentatively, afraid of overcharging. When I looked up the actual time table for charging a 650 cc battery, I was way short. So my battery was probably never properly charged until I charged it for the trip. It appears that my charging system may be able to maintain a battery once it has a reasonable charge. Possible? I've had charging issues before but never had to get into it this far, so I'm all ears.
Or maybe in going over the charging wiring (I also got rid of some excess, open wires) I fixed the problem without realizing it.
Or ... there's a 24 hour gremlin party in my car and one or two of them know the answer. I probably should have mentioned by now that my electrical system in general is the exact kind of thing you would not want to see in a vehicle. Its heavily tampered with, accessories have apparently been added and subtracted regularly... left behind wires, bad looking crimps, missing components, etc. The more I see, the stranger it is. On my way back from New York, the clock ran for the first time for 20 minutes then stopped. Then the dome light came on, also for the first time. The glow plug light is on and off even though I have the plugs on a manual push button system and the original wiring removed. I just noticed that there are two horns installed... the list goes on. I tested for drain with the car off and got about a volt, but repeated the test multiple times and there was no drain (tested both the general drain and all fuses). At some point I should probably replace the whole harness.

I'm allright for now but I'll have to keep on this I think.

[bscutt]

Sounds like you may have fixed it somehow (or the gremlins moved on). I noticed on my Rabbit the other day when it was 11 degrees out, my seat belt light was coming on even though all those leads are disconnected. If I bumped up the heater fan it dimmed and went out on high fan. Back to low fan and the light got brighter. Once the car was warm inside it went out altogether. Electrical gremlins have been rare in my 82 but cold weather seems to get them going. Could be a ground along with metal contraction from the cold. But it all works so a light coming on that means nothing goes into the ignore category.

As for your butchered (modified) harness you might want to solder some things that look flaky or splice in new wires in some places (solder and use shrink tubing). A new or good used harness would probably be nice but they can be a PITA to install. Good luck with it.

[82vdub]

When you are dealing with a heavily modified wiring harness that some other person did and chasing electrical issues, it's probably wise to get another complete harness and replace the whole thing. Yea, it's a lot of work, but how much time do you have in dealing with an electrical issue, when your entire wiring harness is an electrical issue - and likely the very electrical issue you are trying to find? How can you chase an electrical issue when you don't even know the validity of the electrical system you are trying to test? Make sure that the back of the fuse panel isn't all rusted up where you're getting cross connection of circuits too. That's a big one with these older VW's. You could potentially have an electrical fire just waiting to start.

I got a 78 El Camino from Oklahoma and I had the same issue. Battery was constantly going dead, and the dash light dimmer switch was wired to do something funky, and this and that were added, deleted and changed. A new dash wiring harness took care of that issue for me.

[greg lousy]

Yeah, I think thats the inconvenient truth. The back of the fuse panel isn't horrible looking, but I'll take another look. there's some strange things happening between the dash and the battery. Unfortunately, I'm now in the position of riding this out until I can get the jetta going... gotta get around.

[colby]

Just a thought. Get the car warmed up good, up to operating temperature. (At night, seems you have issues with this at night when accessories are on) and pull the glow plug relay out of the panel. I'm wondering if your glow plug relay is sticking on which is causing the massive drop in voltage. Those suckers can draw 40-50 amps, and most of the alternators were only rated at around 65 amps total unless you had AC, which was 90 amps. However, I've been through this before and I ended up getting the alternator rebuilt and installing a new battery.

The alternator I had with similar symptoms had a bad diode pack in it or something and the battery was just plain pooched from years of service and a crappy alternator doing a half-arsed job at keeping it charged. BTW -- the best battery hands down I have ever used in these cars is an Interstate. In my father's 98 TDI, we installed a Group 65 (850 cold crankinga mps), same battery the Ford Trucks use. I'm willing to bet it isn't a wiring issue at all and is an alternator issue, albeit the diode packs or something else, and a tired battery.

[greg lousy]

Yeah, my pick up once had that exact thing happen. I was just as confused until I luckily grazed the wire with my arm and it was warm.. with the car off.
When I bought it the glow plugs were wired through a chinsy, way too low amp-rated switch... I since replaced the wiring and put in a proper ampereage switch. Both systems bypassed the relay. I'll check to see if the relay is still there, but even if it is, I'm sure there's no wire from it into the engine compartment. Wouldn't this make a big draw impossible? I don't think theres a GP relay at all anymore but I'll look again and pull it if there is

Both alternators appeared to be remanned bosch... I think 55 or 65 amp rated. I don't think the diodes could be too bad, or the system wouldn't have recovered (however that happened)