New Bosch alternator problem

[Danpa]

Help!

I'm converting over from a generator to a new Bosch alternator. When I had the 55 year old generator and voltage regulator, everything was fine, gen light on prior to starting then immediately off when it's running.
No issues at all, only upgrading for more amps for the future a/c.

Anyway, installed the alternator and made the wiring conversion under the back seat (3 large red wires and 61 and DF together and ground wire to body). All good clean connections. Battery fully charged, 12.7 volts.
Even checked for voltage at blue wire, with it disconnected and ignition on, 11.6 volts.

Start the car and generator light stays on with 11.5 volts at the battery.

Pulled the alternator back out and had it checked by a reputable alt/gen/starter rebuilder, everything is fine, 14.3 volts on his machine.
Back in the car, same issue.

What am I missing?

Btw, new belt on alternator, not slipping and complete new wiring harness last fall.

Like I said, no issues at all with the generator.

HELP!


Also, don't know if this might be relevant. Turn signals work fine, emergency flashers fine but the light on the speedometer only works for emergency flashers not for the turn signals.
I never could get the light to come on for the signals, not a new issue.
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[redhot]

So - is your new connectinos per the below?

Is your dash GEN bulb working/lighting up (before, now)?

https://www.thesamba.com/vw/forum/viewtopic.php?t=56765&highlight=generator+altenator

[Danpa]

The only difference is that the ground wire that was on the voltage regulator, that went to the generator, is connected to the body where the voltage regulator was mounted. Other than that, I have it wired up the same.

And the generator light worked before and still works. And checking the battery terminals with the engine running shows 11.5 volts.

Dan
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[redhot]

What year car is it (original diagram) and does it have a diagnostic plug/socket in the engine bay?

[Danpa]

It's a 1970, no diagnostic plug. It's a Wolfsburg West harness.

Dan
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[redhot]

So to my understanding you have basically grounded out the wire originally coming from the generator body (#31). Or have you connected it to the altenator body or terminals somehow?

With ignition / all off - 12.7V at battery.
Turning ON ignition ONLY - Oil / Gen lights both turn ON?
Starting engine and blipping throttle - does the GEN light do anything (stay on, go off)?

See this thread - it may be very similar. https://www.thesamba.com/vw/forum/viewtopic.php?t=619303&highlight=altenator+light

A picture of your Altenator and Splice at original regulator position always helps.

[Danpa]

[Danpa]

Is it possible that the built in voltage regulator showed okay on a bench test but bad in the car with a load, trying to recharge the battery?

Dan
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[redhot]

Did you confirm the lights/ignition steps? That would help.

I am thinking it is something with the sensing circuit - either remove the brown wire from alternator (while it should not make a difference since it is just another ground?) and make sure the bulb has voltage with ignition on and grounds through the alternator, while running there is an equal potential.


https://www.thesamba.com/vw/forum/viewtopic.php?t=804944

Did the testing use your voltage regulator or remove it and external item? Brushes are mounted there so the first makes more sense for me?

[Danpa]

[redhot]

Sorry - missed the part inside the quote, my fault.

The fact that the light is ON with ignition and does NOT go out once engine started and blipping throttle even tells a story that voltage is supplied to the bulb when altenator not spinning (battery to ground differential), and does still receive a voltage differential when engine spinning (not supplied voltage from altenator). Is it brighter with ignition only than with engine running?

I am still suspecting something with the sensing part. Also that you have a high voltage drop btw. battery and where you measured in the first post 12.7 vs. 11.6 volts?

Could it simply be that you have too little voltage to the alternator?

[Danpa]

Maybe...
I don't know.

I did try running a larger ground wire from the engine case to the alternator housing, no difference.

Boy, am I sorry I started " upgrading" the system since the shop I had the alternator checked at can upgrade the old, working generator from 30 amps to 50 amps for about 2/3 the cost!

Unfortunately, I found that out after I already had the alternator here from the west coast.

Dan
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[Danpa]

[redhot]

The right resource to hope chimes in is Ashman, while I can only try my best.

So if the test shop tested with or without the regulator, anyhow given the correct RPM and signals in/out, the ALT worked.

Tested without the regulator, that could potentially be a fault source.

Otherwise, it has to be in the in/out signals part.

A great URL and hence the focus on the GEN/ALT light pathway; http://vw-resource.com/alternator_wiring.html. Assume you have not LED bulbs in circuits? So - could it be a bad voltage regulator upfront?

Otherwise the only checks I could think of is to do a set of voltage readings btw. defined terminals/points to just run through all normal checks of discontinuity or high resisrance.

[Danpa]

No LEDs anywhere in the car. And I checked every wire for continuity.

I kinda think the voltage regulator inside the alternator is "stuck".

Like it's feeding the engine, not the battery, if that's even possible.

The supplier is sending me another, hopefully that solves the problem.

Thanks for trying to help!

Dan
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[redhot]

Good luck; gicen that it is common input/out btw. all ALT vs. VECHICLE systems, hopefully it is simply the voltage regulator and that the shop you used tested without it (still a bit puzzled about that....).

Anyhow, soon hopefully to be bright and shiny headlights under ALT power

[kreemoweet]

What is the actual gen/alt warning light bulb wattage? The AL82 Bosch alternator frequently requires a "blip" on the throttle to increase the rpm's and thus the alt output to get it to switch into charging mode. The stock instrument bulbs on some VW's (such as the bus with the little 1.2W bulbs) often have that problem, and using a slightly higher-wattage bulb (such as 2W on a bus) solves the issue.
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[Danpa]

I just checked it and the bulb is a 2 Watt. Also, every time I started it since this problem showed up, I would rev the engine up, just in case.

The replacement should be here this weekend, HOPEFULLY that solves the issue.

I might take this one apart and see if there's any obvious problems, but I'm more mechanically inclined so I don't expect to see much.

Dan
_________________
67 Beetle (gone)
68 Bay Window Double Cab (gone) sob, sob!
64 Beetle (gone)
77 Scirocco (gone)
73 Squareback (scrapped)
70 Beetle, Finally back on the road after 18 years!

[redhot]

Would definitely change over the regulator only (or is it only brush holder?) first and see if it helps - if you have all else mounted while with dual carbs it is easier for sure.

https://www.jbugs.com/product/AL82N.html

https://www.jbugs.com/product/043903023a.html

vs.

https://vwparts.aircooled.net/AL-82-Voltage-Regula...ulator.htm

[Danpa]