Alternator Change on 1968 Bug with Manx Dune Buggy kit

[Govolsguy31]

Got ya. Mine’s green, but regardless, it was hooked up as the alternator/ generator indicator would be. From D+ on alternator to positive on the indicator light. Never lights. Not with key on power or with car running. I manually hooked it direct to positive to make sure the bulb worked, which it does.

Could it be anything other than a bad alternator?

[bsairhead]

[KTPhil]

Post a pic of the front and the back of your speedo. Who knows what year, and the lights changed.
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[chrisflstf]

The alternator light on the speedo has 12v always on one side. The other side of the bulb comes from the alt. When key on, motor off, light s/b on. When you start motor, alt puts out 12v, which then turns light off ( both sides have 12v = no light)

You can also on the engine, take a 12v test bulb, connect one side to 12v and connect other side to alt. If the alt is working after starting, the light will go out.

Some alternators may need a higher idle rpm to start charging, about 800 to 900, but I have not seen that

[ashman40]

See this gallery pic of the trunk side of the speedometer:

Notice the other bulb holders higher up in the speedometer where the bulb holders slide into openings in the metal speedometer body. The speedometer body is grounded which means the upper bulbs are grounded at the sides and the male spade of the bulb holder runs to a switched 12v+ power source to turn the bulb ON.

Notce that the three (3) indicator lamps at the bottom of the speedometer are mounted in a black plastic housing... insulating them from the grounded case of the speedometer. Also, in addition to the three (3) male terminals of the three (3) bulb holders there is a fourth male terminal marked "Power for warning lights". This bottom most terminal is powered with 12v+ from the ignition switch and connected to each of the three bulb holders via the U-shaped conductor. This means each of the three (3) bottom indicator lamp male terminals run to a switched GROUND to turn the lamp ON. If you don't have a wire connected to this bottom terminal you will need to run a new wire from either an ignition switched fuse of the fuse box, or piggy back off the fuel gauge vigrator connection which is also powered from the fuse box.

For the GEN lamp, the wire running from the GEN lamp bulb holder (male) to the D+ terminal on the alternator is GROUNDED by the D+ terminal. 12v+ coming from the GEN lamp runs thru the field coil inside the alternator before reaching ground. This is why you cannot use one of the upper speedometer bulbs as your GEN lamp... it is not providing the 12v+ needed to energize the field coil in the alternator.


If you don't have a GEN lamp....
Find a 2W 12v bulb and wire it between the ignition coil #15 (+) terminal and the D+ terminal of the alternator. This lamp will act as the speedometer GEN lamp. It will turn ON with the ignition key before you start the engine and energize the field coil. Once the engine is started and the alternator starts producing a charge this temp GEN lamp will turn OFF. This will work until your normal GEN lamp arrives.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Govolsguy31]

These two most recent posts might fix me. I didn’t realize one side was to be connected to positive and the other to alt. Here’s pics of my speedometer and a couple YouTube links. I’ve promised to grill the wife steaks, so further testing will have to wait till tomorrow.

YouTube video links:
https://youtube.com/shorts/ykCS8FAK8Ig?si=f7NOBSHs1L8uvOGc
https://youtube.com/shorts/WlOHfYn9rOE?si=MKb4qlhnqYZnG8SP

[bsairhead]

The tab by your pinky gets key on power.

[KTPhil]

As I suspected, your speedo is not form the year of your chassis (no gas gauge is the easy giveaway).
Your older speedo is simpler and so this should be straightforward.
One thing to know about the turn and warning lights at the bottom is that they are reversed polarity from what you may expect. The center tab has key-on power. So the light bulbs light up only when the bulb terminal is grounded.

So for example, your oil light comes on when you turn they key to the run position, because one side of the bulb has power, and the other side, which is connected to your oil pressure sensor, is grounded when oil pressure is low (like with the engine not running). ONce the engine starts, the oil pressure REMOVES the grounding of that wire, so the bulb goes out. Make ssense?

Similar for the turn signal indicator light and the generator/alternator light.

So first confirm that the triple bulb holder at the bottom of the speedo has positive voltage when you turn the key on. Then report back.
_________________
Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[ashman40]

Ignore the bit of my post about fuel gauge vibrator as a source for 12v+ for the bottom three indicator lamps... only applies to '68-later Beetle speedometers. Yours is a pre-'68 speedometer.

The three bottom indicator lamps on these earlier speedometers were powered directly from the fuse box (ignition switched fuse)
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Govolsguy31]

Guys and Gals, yall are amazing! Your input was a huge help and I got it sorted (I slipped away for a few minutes after dinner, don’t tell the wife) . I put 12v to one terminal and one to the alt. Light clicked on, started car, and it went out. Voltmeter test and I was registering 13.8v at idle.

Once I get the new sockets and bulbs for the Speedo, I’ll get it wired up correctly. I’ll post a few pics once she’s back together!

[bsairhead]

Cool beans

[ashman40]

[Cusser]

[Govolsguy31]

I have learned a crap ton on this. That’s as much fun as driving it.

I was able to pull that bulb and bulb socket and get it in the right place. I ordered 4 of each that will be here Monday, but I was able to get the dash put back together. I also installed a small 12” LED light bar, which went smooth.

[bsairhead]

Now get that oil pressure light wired.

[Govolsguy31]

[bsairhead]

[Govolsguy31]

[bsairhead]

[Cusser]