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Thu Jul 10, 2014 9:43 am

Gen light WAS stuck on red
Replaced new battery leads
Replaced alternator
Fan belt and tensioned

The red gen light has now gone out when I flicked the headlight switch, then I couldn't turn the side lights off until I took the keys out. Can someone tell me which wires I need to be looking at, I'm guessing the light switch, what's causing it?

Thanks

Thu Jul 10, 2014 12:13 pm

Find type (1-2-3-4) and year here and look at diagram of light switch and ALT/GEN lamp in speedo...

http://www.thesamba.com/vw/archives/info/wiringt1.php

Dale

Thu Jul 10, 2014 12:54 pm

Thanks for the info, I tried my best but it makes no sense to me! Sorry.
Any ideas what component the gen and head lights run to, or which fuse I need to look into. I'm guessing I need to have a look at the headlight switch.

Fri Jul 11, 2014 9:26 am

Gen light stays on until I put the headlights on, then it turns off. My sidelights stay on when the ignition is in the off position. Any ideas anyone?

Fri Aug 08, 2014 1:02 pm

Right......

Gen light on
New alternator, new fan belt all nice and tight
Gen light still on

Found burnt and melted wires on the left side of the car running front to rear, turns out the number plate light wire was snapped touching metal and shorting out the fuse. The previous owner put a very large fuse in its place instead of tracing the short, hence the burnt wires inc the alternator wire.
I replaced all burnt and broken wires, put the correct fuse in and changed the inners of the alternator...... Gen light still on!!!
At one point the oil, gen and fuel gauge didn't work nor did the car start up, now it's starting the oil light is out, fuel gauge working but gen light still on.
The alternator still isn't charging

Help...... Please

Fri Aug 08, 2014 1:44 pm

Alternator will not charge until you get the light circuit working, it triggers the regulator.

Fri Aug 08, 2014 2:07 pm

The lights are working, the gen light is permanently on when the keys are turned. I'm stumped.

Fri Aug 08, 2014 2:30 pm

14platoon wrote: The lights are working, the gen light is permanently on when the keys are turned. I'm stumped.

Does light go off (with key on) when you pull wire off D+ terminal of alternator....

Dale

Fri Aug 08, 2014 3:18 pm

Do you mean the blue one that sits on top? If so then yes it goes out when you take it off.

Fri Aug 08, 2014 4:23 pm

Have you cleaned and checked the ground of the alternator?
Edit: Please ignore, I was thinking about fiberglass bodies.

Fri Aug 08, 2014 5:10 pm

14platoon wrote: Do you mean the blue one that sits on top? If so then yes it goes out when you take it off.

If lamp does not go out as you spin up motor to maybe 1600-1800 RPM.... You "new" alternator is bad....... Is it a "Chinese Republic Authorized Product" (CRAP)....

Dale

Fri Aug 08, 2014 5:14 pm

Could a weak battery be the cause of the gen light to come on. It is probably flat due to the burnt and broken wires.

Ps I changed the internal electrics in the alternator, in total that's 3 lots of new electrics inside the alternator.

Fri Aug 08, 2014 5:24 pm

14platoon wrote: Could a weak battery be the cause of the gen light to come on. It is probably flat due to the burnt and broken wires.

Ps I changed the internal electrics in the alternator, in total that's 3 lots of new electrics inside the alternator.

But you did not fix problem.....

If you pull wire off and light goes out, only place you can get ground to light lamp is through internals of alternator.... All indications are wiring and lamp is good right up to D+ terminal on alternator...

It either has bad diode(s) or bad regulator.... OR some other mysterious ground on D+ terminal from inside alternator....

Dale

Fri Aug 08, 2014 5:40 pm

I have just replaced the wires which were burnt completely, this included the alternator wires. My thoughts were, if the wires were burnt causing the alternator to fail and the Gen light ON, now that I have replaced the burnt and melted wires the problem should be fixed. As the wires weren't reaching the Gen to charge it, this has flattened the battery. Would this cause the Gen light to stay on if I found the solution by replacing the burnt wires but the battery remained flat?

Sat Aug 09, 2014 6:48 am

14platoon wrote: I have just replaced the wires which were burnt completely, this included the alternator wires. My thoughts were, if the wires were burnt causing the alternator to fail and the Gen light ON, now that I have replaced the burnt and melted wires the problem should be fixed. As the wires weren't reaching the Gen to charge it, this has flattened the battery. Would this cause the Gen light to stay on if I found the solution by replacing the burnt wires but the battery remained flat?

Battery remaining flat is either defective battery, or alternator not putting out voltage to charge battery. Does battery retain charge when charged with external battery charger?

BUT wire fix it did NOT SOLVE THE PROBLEM so the thinking of wiring issue is incorrect...

Alternator theory and designs dictates it puts out a ground on D+ wire when it is at rest or not functioning.... As alternator spins up with engine start procedure a simple shot of 12 volts (though idiot lamp) put into alternator to initialize the field and start generation process.... As alternator spins up and produces voltage, the ground on D+ transitions from "ground" (to light lamp) to 12 volts (same as battery voltage)... When you have 12 volts on one side of bulb and ground on other side of bulb lamp lights because you have current flow through bulb, as the transition occurs on D+ terminal the "ground" is replaced by 12 volts once voltage come up on alternator B+ terminal you cease to have current flow as you have same potential on both sides of bulb and DO NOT HAVE CURRENT FLOW therefor you do not have lamp lit (glow)... The theory dictates that you proble is you are not getting transition on D+ terminal in alternator there for "ALTERNATOR" is defective....

The proof is when you disconnect lamp from D+ terminal of alternator lamp goes out, this is exactly how it should be as to wiring and lamp function... IF you ground wire taken off D+ terminal to engine/chassis and lamp comes on (key on) and or if you touch the wire to the B+ terminal (terminal with large wire from/to battery) and lamp goes off then wiring and bulb are good....

Dale

Sat Aug 09, 2014 6:56 am

14platoon wrote: I have just replaced the wires which were burnt completely, this included the alternator wires. My thoughts were, if the wires were burnt causing the alternator to fail and the Gen light ON, now that I have replaced the burnt and melted wires the problem should be fixed. As the wires weren't reaching the Gen to charge it, this has flattened the battery. Would this cause the Gen light to stay on if I found the solution by replacing the burnt wires but the battery remained flat?

Changing out all fried wires are your first order of business otherwise how can you expect to rectify the problem.
Check everywhere the wires enter and exit the body for chafing.
Using a multi-tester as you go will help find grounded wires but all burnt wires must be isolated from the circuit and replaced for it to work.

Sat Aug 09, 2014 9:12 am

Just to clarify,
I found a broken wire to the number plate bulb. The previous owner put a high rate fuse in, instead of finding why the original fuse was blowing. The number plate wire was split and touching metal. I originally believed this is what caused the wire loom to melt ( due to the high rated fuse).
This burnt wire had burnt through the alternator wiring through to bare metal and some other wires.
I have now replaced that loom, now have working number plate light etc. the gen light is still on.
Further investigation found bad wiring to a headlight, this was probably shorting as well, that's now replaced.
While putting the dash back together, the screen washers now don't work, the full beams don't work and the blower heater doesn't work. While I was putting the dash together something blew the fuse, I checked the earths etc but haven't found the culprit. Is there a common wire or terminal that connects all of these?
By rights I believe the alternator should work, I have power to it and the gen light shows on the speedo?

List of things that have stopped working

Horn
Full beam
Washer
Windscreen wiper
Blower motor

Gen light still on

When the engines not running, the battery is reading 12.42v

Sat Aug 09, 2014 12:24 pm

Dale, thanks for your replies.

I carried out one of your tests.
I turned the keys to the on position
Took the blue wire off the alternator terminal and the gen light went out. I touched this wire to the fat red one on top of the alternator and the gen light stayed out. I then ground the blue wire to the chassis and the gen light came on. Am I correct in saying that this shows the alternator is fine, if so then why is the gen light permanently on. I'm thinking I have a gremlin in the dash somewhere.

Sat Aug 09, 2014 1:43 pm

14platoon wrote: Dale, thanks for your replies.

I carried out one of your tests.
I turned the keys to the on position
Took the blue wire off the alternator terminal and the gen light went out. I touched this wire to the fat red one on top of the alternator and the gen light stayed out. I then ground the blue wire to the chassis and the gen light came on. Am I correct in saying that this shows the alternator is fine, if so then why is the gen light permently on. I'm thinking I have a gremlin in the dash somewhere.

Just the reverse... It proves "problem" that is causing alternator light to stay on, is in alternator, it proves dash lamp is functioning correctly ... You need to grasp concept that all the repairs on alternator never fixed issue... Does your OIL lamp function correctly, does your turn signal indicator function ok....

Go back and read the post on "alternator theory" again.... You have missed the part how the ground transitions to power (12 volts) on D+ terminal to turn lamp off....

Dale

Sat Aug 09, 2014 1:52 pm

Oil light and turn lights functioning correctly.
Trying to get my head around this, so there is power to the bulb, but past the bulb towards the alternator the power is not being converted from ground to volts? Suggesting the alternator isn't generating the voltage.?
This is the second alternator with new innards?
Ps you may have to explain it like I was 5 years old.
Any ideas what happened to the other instruments, it blew a fuse when I put the speedo back but now all that other stuff I listed isn't working. I'm pretty stumped now to be honest.

If I replaced the alternator with a new one before the burnt wiring was seen and fixed ( it was burnt right through) would this have fried the new alternator diodes?

Update

I have completed a test of the diodes
Battery off blue wire D+ disconnected
Holding red terminal to the D+ and the black terminal to the body showed a result of 943

When I put the blue wire back on although battery still disconnected showed 008

Further update!!

I have tested the alternator with just the ignition keys turned on
12.43 at the battery input post on the alternator
1.42 at the D+b terminal on the alternator
I believe that shows everything working as it should except the NEW alternator ( as Dale explained earlier). I think I may have fried the new alternator prior to replacing the burnt wires which I didn't know we're there!
If this rings true let me know, if not the please let me know sooner before I waste more money on another alternator!!

I believe the other dash gremlins fault is something altogether different.