TheSamba.com :: View topic - Red Light ON -> How to tell if its the alternator or Regulator

Fri Jun 14, 2024 6:55 pm

Folks
I need to diagnose if its the alternator or regulator. Any pointers or suggestions beyond the steps in Muir? Once I have the steps and figured out which part I need, I'll come back to ask where best to source.
thanks again!

Fri Jun 14, 2024 7:33 pm

I’ll send this to telford but as I told you before, you probably fried your alternator diodes. That said, Telford can tell you what to do.

Fri Jun 14, 2024 9:48 pm

To diagnose, we remove the regulator from the circuit and run the alternator unregulated. Caution: to avoid damage, follow instructions EXACTLY!

1 - unplug the regulator
2 - make up a jumper wire about 4" long with a male spade terminal on either end.
3 - using the jumper wire, connect the red and green regulator connector wires together.
4 - connect a voltmeter across the battery.
5 - start the engine - DO NOT REV!
6 - while watching the voltmeter, slowly increase the engine speed. The battery voltage should increase. Do not let it exceed 15 volts. If it increases, there's a problem in the regulator. Otherwise, problem in the alternator.

Fri Jun 14, 2024 9:51 pm

I knew that but needed to confirm, I’m kidding

Sat Jun 15, 2024 2:04 am

I’m sure the above troubleshooting will reveal a culprit.

However, I chased a no-charging issue back and forth between the alternator and regulator for several days. (Mine was no ALT light.) Troubleshooting indications on different days would send me different directions; bad alternator one day, bad regulator the next.

I would recommend you re-check ALL the connections, wire by wire to make sure they are where they belong and making good connections.

I double checked the alternator twice and bought a new regulator only to find that it was a bad connection (behind the dash) that was the problem.

I now re-lug anything suspect and verify every connection with a multimeter and in accordance with the wiring diagram.

Sat Jun 15, 2024 10:57 am

telford dorr wrote: To diagnose, we remove the regulator from the circuit and run the alternator unregulated. Caution: to avoid damage, follow instructions EXACTLY!

1 - unplug the regulator
2 - make up a jumper wire about 4" long with a male spade terminal on either end.
3 - using the jumper wire, connect the red and green regulator connector wires together.
4 - connect a voltmeter across the battery.
5 - start the engine - DO NOT REV!
6 - while watching the voltmeter, slowly increase the engine speed. The battery voltage should increase. Do not let it exceed 15 volts. If it increases, there's a problem in the regulator. Otherwise, problem in the alternator.

Finding:
Reving did not increase voltage (steady at 12.6V); so alternator is shot:
Its a camper, so first I need to pull the alternator to find out amperage/part number.

What is my best option now:
1. Replace with aftermarket -> saw a thread about B+ shorting through the alternator housing, so lots of concerns here
2. Repair mine -> Seems complicated, not sure I can source the diodes easily
3. Get mine repaired -> anyone providing this service on thesamba?
4. Get a used replacement -> who would have one?

Thanks folks!

PS, i'm having trouble removing the tin around the alternator (single slotted screw from the bottom, its stuck! trying different things: fun never ends :)

Sat Jun 15, 2024 4:21 pm

Update: I was able to remove the alternator!

1. its an AL75X

was this the Factory Installed one? I believe campers had the higher amperage one? so want to make sure

2. I need to order the rubber boot as well, seems like it cracked, hopefully I can find a replacement

3. I noticed another 'wire' see regulator below, i believe its non-factory, can someone confirm? I had removed the Blue one as that was connected to the previous owner circuitry that caused a short a week ago, this particular one is going into the firewall, not sure where...

4. I lost the nut where the alternator pivots; I believe its 13mm. Hopefully its just a normal nut, and not 'square'...someone please confirm.

5. Here's the starter connection of the cable going to the alternator, hope all's legit and ok!

6. While removing the alternator, I found a broken wire cable that goes through a pulley, i believe...I'm not sure what that is, I'll start a separate thread on that, since its unrelated to the generator

Looking for some answers on my previous post to help with direction on what to do next. thanks everyone!

Sat Jun 15, 2024 4:37 pm

here’s the boot for the 55-amp alternator.

https://www.buslab.com/product-p/021903655b.htm

other vendors have it as well.

some buses came with the al108x (70-amp). i think those with eberspacher heaters. my ‘78 champagne westfalia had a 55.

upgrading mine to a 70 required some different tin, wiring, and plastic gasket.

as to the pivot-bolt nut. pretty sure it’s a 8mm hex. it just fits a 13mm wrench.

Sat Jun 15, 2024 9:36 pm

That extra blue wire is the charge warning light wire to the dashboard. Without the idiot light coming on with the key, the voltage regulator won't get the signal to start regulating voltage.

Looks like disconnecting the batteries and polishing the starter connections would be time well spent, but congrats on having all good factory connections. Nothing like those ten cent plastic crimps on the biggest electrical junction on the car. :lol:

Count every terminal as they come off, so you don't forget one and start a fire. No need to disturb the other dirty 13mm nut on the starter unless you're rebuilding the whole thing.

Once the ring terminals are off, hold the crimped part of the wire with needle nose pliers while using a wire wheel in a Dremel on the ring faces. Nice and shiny? Put them back largest wire to smallest wire. And DON'T lose that 13mm M8 nut, it's thin, to remind you not to overtorque the starter connection.

I wire brush the upper spades, and use a pipe cleaner inside the push-on connectors. Do not connect any wires to a lower push-on lug. Some starters have an extra connection here and no VW uses them.

New Bosch AL75's are trickling onto the shelves. The X means rebuilt, I think. I would go that route for the warranty if you can get one. Otherwise, find the old stinky electric motor shop in town and ask around. It pays dividends to have local collaboration.

There is no concern about B+ shorting out, because you will check your replacement alternator regardless and adress it in one of two ways:

1) Cut the threads with a Dremel wheel after installing the wire and nut.
2) Drill a 1" hole in the backing plate exactly over the B+ terminal. Install a waterproof rubber plug in the hole, and now you're future-proof! Also go back and do step one.

Robbie

Sun Jun 16, 2024 6:03 am

Thanks Airscooled

Is there a particular plug you used? I really like that idea!
I’ll follow the rest of your post once I get the new alternator, thanks for the pointers!

Sun Jun 16, 2024 8:13 am

I had something like this on my last alternator swap, you can usually find something suitable in your knick-knack drawer. Make sure it’s a snug fit, or RTV it in place if you drive through dust or foul weather frequently.

https://www.detroitmuscletechnologies.com/mopar-hole-plug-1-1-000-recessed-rubber-floor-trunk/

Again, trimming the post is ideal. This just buys you flexibility down the line when your alternator goes kaput in a parking lot and you have to swap in a FLAPS replacement.

Robbie

Tue Jun 18, 2024 4:23 am

No need for a separate thread for 6. the broken cable that goes the pulley. That is your thermostat cable which controls the cooling flaps.

Tue Jul 16, 2024 4:15 pm

@airschooled,

thanks for your suggestions, I finally made the modifications to the alternator cover to clearance both B+ posts, also the nice flexible rubber plugs that I got from amazon fits really well https://www.amazon.com/dp/B07B7HHM1Q?ref=ppx_yo2ov_dt_b_product_details&th=1
I do have a question, you mentioned that in the future this might come in handy in case I am stuck and need to use an alternator from a FLAPS. Do you have any pointers on 'equivalent' alternators that cna be used in case I am in such a predicament in the future?

Tue Jul 16, 2024 5:37 pm

There aren't any drop-in replacements that I know of, but most FLAPS will charge your battery for free…

As always, when given a "no," also ask about Porsche 914 alternators and other listings they have for your year VW. Some places list combinations of Campmobile, Transporter, Type 2, Microbus, etc.

Robbie

Tue Jul 16, 2024 5:46 pm

Thanks again

Now as I was putting it back together - ground the posts down and painted the exposed metal for the two holes to prevent corrosion - I need to source the two rubber boots that go around the harness - one that plugs into the alternator housing the other goes into the firewall - they’re falling apart :(
Anyone know if it’s available someplace?

Tue Jul 16, 2024 7:20 pm

replying to myself, the part is 021971907A
I was able to find it at https://www.jimellisvwparts.com/products/volkswagen-vw/Jetta/GROMMET/5124185/021971907A.html

Wed Jul 17, 2024 12:00 am

That’s a premium rebuilt piece of junk.

Vintage auto electrics are best repaired by hunting for an “ auto electric shop” that caters to English cars, especially. These guys source parts that aren’t pot metal from overseas for armatures, diodes, bearings.

The warranty you get from the parts stores just means you have guaranteed junk in the box, not a good part.

Wed Jul 17, 2024 7:59 am

Thanks @abscate
The order got cancelled because it was on back order
I’m in Austin, TX…not sure we have such a shop jere
I’ll try the classifieds on here - if anyone else has any tips where I can get one please let me know
Thanks!

Wed Jul 17, 2024 9:01 am

Looking at your breaks/discolorations in the original sheath, you're probably better off going new. Like Kyle's FI harnesses, this would take me hours to make and cost hundreds more. Buy it while you can:

https://www.busdepot.com/021971349f

Wed Jul 17, 2024 10:28 am

Thank you! Will do.