Not charging.... question about Alt. wiring

Guess the black is a ground... probably needs to be hooked to the pan somewhere...

The light in the engine compartment was probably set up as the VW was, the light needs to be there so that the alternator field turns on. If the engine is running and the the DVM hooked to the battery should indicate 13 to 14 volts if the alternator is putting out. As to the black wire you need to now where its coming from before you connect it to anything.

 

This may help.

 

http://www.vw-resource.com/alternator_wiring.html

The black wire is coming off the ground lug on the top of the alternator as shown. You'd think that massive clamp holding the alternator on would ground it. Unless it's an internal thing. Look at the pic and you will see what the black wire is attached to on the alternator... Obviously it goes nowhere right this second.

PS- how can I tell
If this is internally regulated or externally? This jerk who wired the car before me and I'm sure before him was amazing. We removed 7 relays and 1 mystery box that were hooked to wires than ran to nowhere and some had no wires, just screwed to the underside of the dash. I suppose it's possible I removed a working regulator? Can you guys tell by my pic if it's internally reg'd?

I would cover that terminal on the alternator where the hot red wire is attached. Sparks could go flying if it gets shorted out.

Joel

The black wire would be grounded but is really not the issue at this point as everything is connected to itself from engine to frame. The alternator as I view it needs  a regulator as an internally regulated alternator will have it mounted to the unit with the brush block assembly incorporated with it. i.e Motorola and Bosch.

 

Again I believe the light in th engine compartment was there for a reason, to excite the field, turn it on.

 

http://www.youtube.com/watch?v=QRnYsmOg7v8

Mike wrote:  "Again I believe the light in the engine compartment was there for a reason, to excite the field, turn it on."

 

Well, you're partially right - the alternator needs a way to excite the magnetic field and a light is used to do so, but NOT a 'light in the engine compartment'.  Although I suppose that might work, it's just a bit unusual - especially when you want to see if the alternator is charging while sitting in the driver's seat.  Maybe he had his girlfriend hang off the back of the car with the engine lid open to see the light?  Given what we've heard about the previous owner, I guess anything is possible!! 

 

The D+ lead (the smaller, blue one behind the big, red lead on top of the alternator) should go to the "alt" light at the bottom of your tachometer to tell when the alternator is not charging.  It's very important that the dash lamp is working (i.e. - not burnt out) because if the lamp is defective or not wired correctly, then the alternator will not charge.

 

This light is a bit different, because one side goes to that D+ tab on top of the alternator, while the other side should be insulated from ground by a plastic block (part of the lamp mount on the tach) and should go to the ignition +12V (the same wire that feeds the coil's "+" lead).

 

The way it works is: the key is turned on and the alternator gets 12V fed to the D+ tab through the alt lamp in the tach and the lamp lights (at this point, the D+ tab is acting like a ground point for the lamp, making it light)  

 

The engine is then started and the alternator's magnetic field starts producing voltage and current, but it puts out more than 12V when charging (usually 13.9 volts) and balances out the 12V coming through the alt lamp and it goes out (because the D+ essentially goes from being a ground to being +12V and +12V on BOTH sides of the tach lamp makes it go out).  

 

If the engine idles slowly enough that the voltage coming from the alternator drops below the level of the charged battery, the light should come on until the engine speeds up to re-balance the circuit.

 

I would first check the tach bulb on the other end of that blue, D+ lead and then check to make sure everything is wired correctly.  

 

Oh, and that Black wire attached to the alternator case?  Very unusual.  The alternator case CAN be used as a ground point, but it looks a whole lot cooler to find some other place for it.  Trace where it goes and let us know what the other end is attached to - I'm curious, that's all - and maybe you could move that lead to somewhere else.

 

BTW:  on your comment about removing a bunch of wiring and relays to clean things up, I've got my engine and transmission out and been looking around under my car (which I built) and now remember that I have separate relays under there (and in different places) for the starter, for the oil cooler fan and for the O2 sensor heater.  Your PO might have been an electronics tech or engineer with lots of stuff kicking around in his "junk box", too!

So I guess I have two questions... Is this thing internally regulated? The Samba guys can't tell me either... The next is this. The black wire was a lead that went to hit engine bay light I think.... It goes to nowhere now. It's 2' long and stops. My blue wire does go to the bottom of the speedo in one of those ultra dark and hard to see lights. I understand now I think. I do recall driving home one night and saw a little tiny red light on the bottom of the speedo, but it wasn't always on. I did see it on once at speed... but it's not always on. I don't see it on at all now with the key switched on. Is that 1/8" light enough draw to make it work? So I see now I think. I have a blue wire going to a small light on tach. I should trace another wire going from the same bulb to my dash mounted key? I'll go look. 

I missed the link... That is helpful. I need to make sure a blue wire goes to a bulb, and also coming out of the bulb is a wire that goes to my accessory side of my switch? My switch looks like his does....

Ah ha!! My buddy who's wired a bunch of cars successfully has been tricked I think. I found my blue wire, traced it to the little bulb at the bottom of the tach. Now, in one side is my blue, out the other side is what appears to be a black (ground) jumper wire to the next small bulb over which goes to the other small bulb with a green wire on the other side. This is a VS harness and basically VS gauges.  I need to cut the jumper and run a wire from there to accessory! Right?

Yup.

 

Just be careful, though, that the particular light you use isn't grounded by inserting it into the tach housing - it should mount into a plastic housing.

VW wiring uses black as the color for switched +12V. Brown is the color for grounds.

 

The lights are individually grounded through the pressure sensor or alternator respectively so you will have a wire from each bulb going to each of those locations. Your blue wire (to alt) and i'm guessing the green (to oil pressure sender). Verify what the green wire goes to before doing anything.

 

The Oil Pressure and Charging lights typically share a single switched +12V power wire. On many guages, there is a single tab that is a common power bus for those indicator lights. If your light sockets instead have two tabs for each bulb instead of one, you will have +12 V switched power going into Tab1 of Bulb1, a jumper between Tab1 of Bulb1 and Tab1 of Bulb2. Tab2 of each bulb gets connected to its respective sender/alternator. You should not have any ground continuity at any of the bulb tabs when the wires are disconnected.

 

From your description, you are missing the +12V switched power wire that should connect to one of the tabs the black jumper wire is on. But a picture would help verify what might actually be going on.

 

 

And yes, your alternator is internally regulated.

Okay an update. I ran a wire from the excess read to the spade on the other side. I removed the ground jumper wire that he used as a ground. The light is on when I started and goes out after a few seconds. The plug that I used has a plastic insulated housing that goes into the tag. I can also verify that I am charging at 13.6 volts now. I think I fixed my issue thank you to you guys. I also got my hidden speakers and stereo going sounds great. Can't wait for this warmer weather.

Is your Oil Pressure light still working? It should turn on with the key on, engine not running, just like the charge light and go out when the engine is running. I'm guessing you've disabled it when you removed the jumper wire.

I'm not sure my oil light was ever on in the run position!! How should it be wired? It's a green wire to one side of the plug and ground?? On the other. Didn't i ha to remove the ground wire? How's that work if you ground it, the alternator light would go out???? His jumper wires were ground wires. Not jumpers from accessory switched power...FYI 

 

Is this accurate? Obviously I'm not going to wire a horn in there...

http://www.clubvw.org.au/oldart014#ele01

Switched +12V power goes into one side of the Oil Pressure bulb. The other side of the bulb is wired directly to the oil pressure sender. When you have no oil pressure, the contacts in the sender are closed, connecting its electrical connector tab to its case/threads, thus connecting the sender's tab to ground through the engine case. This completes the circuit and the bulb lights. When the sender gets pressure with the engine running, the contacts open, breaking the connection and the light goes out.

 

But like I said before, you need to verify that the green wire is the one going to your oil pressure sender before you change anything. If it's going somewhere else, you may cause damage if you wire things wrong.

 

Yes, that first diagram is correct. And like I said earlier, often the way that circuit is actually done with 2 terminal bulb sockets like you're describing, is the switched +12V wire goes to Tab1 of Bulb1, a jumper wire runs between Tab1 of Bulb1 and Tab1 of Bulb2. Tab2 of Bulb1 goes to alternator D+ terminal, Tab2 of Bulb2 goes to oil pressure sender. It saves you from having to run two separate +12V power wires from the fuse box to the gauge lights.

 

I feel we may be using different definitions for the term "jumper" which may also be causing some confusion on my end. A wire from power or ground to a device is not a jumper wire. A jumper wire goes between devices to connect their terminals together or between terminals of the same device to short them together. For example, lets take two devices, DeviceA and DeviceB. Each one has one power terminal (#30) and one ground terminal (#31). In order to wire them so both devices are powered and so we don't have to use separate power and ground wires to both, they would be wired as such:

 

Wire 1: +12V to DeviceA #30 (not a jumper)

Wire 2: Ground to DeviceA #31 (not a jumper)

Wire 3: DeviceA #30 to DeviceB #30 (jumper)

Wire 4: DeviceA #31 to DeviceB #31 (jumper)

 

Again, a picture would really help me here.

I am completely following you. He had made ground jumpers on the other tabs. The VS diagram didn't include anything on those tabs and he assumed ground. The jumper needs to be hot as you suggested. The green wire does go to the sender. You guys made perfect sense of this. Thanks.

Which is pretty cool, because I often don't make much sense, even to myself!

I'll second that! 

Hahah. Well. Gordon, you've helped me a lot... I'm your translator I guess