Motorola alternator not charging battery

[Sgt Pepper]

I have a 1971 Super Beetle convertible. The previous owner put a Motorola alternator in this car. It's the kind that has external regulator. The battery is not getting a charge from the alternator. I checked wiring and it's wired exactly as the diagram I'm posting shows. The charging system light is not coming on with key in the On position. I have tried new bulb, new wire, new socket, and checked fuses, and all still no light. Is it possible that a bad regulator is causing this issue? I have checked everything and no luck. On a positive note, what I thought to be a broken Sapphire radio was just an unplugged connection.

[paranoid56]

check the voltages at each point and figure out where the bad part is.

[Sgt Pepper]

[Danwvw]

Maybe maybe-not!

I've got a Motorola Alternator in my 71 Bus. It's kind of a weird thing to have but it has worked well for me and I have rebuilt a couple of them for spare parts etc..No body want's them!
But Yeah, Sounds like the 61 wire is not connected or the lamp socket in the speedometer is bad or something. Got to have that light to start it charging. Check that there are 12 volts to the Alt/Gen Indicator lamp ring contact on the back of the speedometer when the key is on. (Engine not running for this test.) The tip of the socket goes to the 61 wire and that goes to the D+ on the alternator as well as the Voltage Regulator, I use a cheap aftermarket voltage regulator on mine.
This one should work: 1974 VW Beetle Alternator Regulator.

_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Sgt Pepper]

[ashman40]

[Starbucket]

I had a Motorola internal reg. alt. that when it quit charging there was 1 brush under the 3 screws to the piece that the wire connectors are on the alt.. I replaced that and all was well. Seems like a 12v test lamp to replace the speedo light for testing would work to see if your speedo lamp socket/ground is bad.

[Danwvw]

This RockAuto external E695 looks like the voltage regulator that I installed on my 1971 bus with the Motorola Alternator above but mine was a "Standard Motor Products" I think? But 695 rings a bell. RockAuto, Mine just had 3 wires that I matched up color to color with the Original Motorola Connector that I was lucky enough to have. But If the Blue wire on a 4 prong regulator is the lamp wire then it would be cool to wire it up, I had to make a splice into the D+ wire to wire the 3 prong regulator.
_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Sgt Pepper]

Thanks everyone for help. Tested gen light circuit and it's working as it should. Checked D+ terminal and sure enough between 3.5-5 volts was coming through. My understanding is the internal circuitry is messed up as less than 1 volt should be coming through. Looks like I'll be converting to a new alternator, built-in regulator.

Anybody think I could sell the old voltage regulator? What about the generator itself? I'm sure someone could want to rebuild it. I don't want to just throw the parts away.

Thanks again!

[Danwvw]

[Sgt Pepper]

[Sgt Pepper]

I'd like to credit ashman40 with the information I found in an old post. I wanted to copy and paste it here in case somebody else has this issue in the future. Here is what ashman40 wrote:


For future reference, here are some tests to verify the alt/gen lamp circuit are working. These tests start from the front of the car and move towards the rear.
1) Test for 12v on the black (or green) wire that connects to the bottom most terminal of the speedo. This is the common connection that provides 12v+ to the three indicator lamp bulb holders at the bottom of the speedo. With the ignition ON, disconnect the black wire and test the end of the wire for 12v+. If there is no voltage on this wire, check the fuse at the other end of the wire. Early Beetles did not protect this circuit with a fuse.

2) Test the bulb holder socket of the speedo. Reconnect the wire to the bottom of the speedo. Remove the Gen lamp + bulb holder from the speedo socket, With the ignition ON, test the inside of the three bulb socket at the bottom of the speedo for 12v+.

3) Test the bulb holder. Put the bulb and bulb holder back into the socket of the speedo. With the ignition ON, run a jumper wire between the male terminal on the end of the Gen lamp bulb holder and a good ground. This should cause the Gen lamp to turn ON.

4) Test the Gen lamp circuit. Reconnect the blue wire to the Gen lamp bulb holder. Go to the rear of the car where the other end of this wire is located. If you have a gen with external regulator the blue wire ends at the #61 terminal on the VR. If you have and alternator, the blue wire ends at the D+ terminal on the alternator body. Disconnect the blue wire and with the ignition ON, touch the end of the wire to ground. The Gen light should turn ON.

5) Test the voltage at the D+ alternator terminal. With the ignition OFF, remove the blue wire from the D+ terminal of the alternator. Place your voltmeter probe on the D+ terminal of the alternator. Test this terminal for voltage. If you find a small voltage (<1v) you are okay. If you find any higher level of voltage on this terminal it usually indicates the alternator internal diodes have failed and current coming into the B+ terminal is leaking out the D+. The alternator will need to be replaced/rebuilt.

[ashman40]

Did you run all the tests suggested on the Pelican Parts link for 914 alternators? What were your results? Any voltage readings should be done with the engine running at least 2100rpms.


From the link I posted above:

[Sgt Pepper]

[ashman40]

[Sgt Pepper]

One last question. Is the pedestal for this externally regulated Motorola alternator the same as the one for a Bosch AL82? I don't want to spend the extra money if I don't have to.

[Danwvw]

Yes, they are the same. Give you 10 dollars for your (Motorola Alternator and connector and external voltage reg.).. Maybe give you $30 if it turns out to be a good one.
_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Sgt Pepper]

[Danwvw]

Yes, No hurry, Glad the new alternator fixed it for you, good call!
_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Bashr52]