Stock Guage, Aftermarket Flasher & Switch

[CBDZ]

This one has me stumped. I am still using a stock '73 gauge, which has a single power source for the oil pressure indicator, charge indicator, and turn signal indicator.

My understanding is this...
Oil Pressure Indicator - Grounded when no pressure, light on
Charge Indicator - When current flows from Alt./Gen. cancels current flow. Which turns off light.
Turn Signal - Stock flasher relay has a grounding terminal, which is grounded when signals are active.

Now, If I am using a non-stock relay, which doesn't have a grounding pin, is there a way to make this work, or do I need to use a flasher which has a grounded connection? If not, does any body know of a non-VW flasher that has a ground terminal. I should I just use a VW flasher?

[Marc]

Compare the schematics of a `70 Beetle with 4-pin flasher and a `71 with the 3-pin. The one that was deleted is KBL, an auxiliary output to make the pilot lamp flash in unison with the external lamps. On `71-up, the design was simplified by the removal of the auxiliary contact and the pilot lamp flashes in alternation with the externals...by connecting it to the same output (49a) as them, you get the same effect as with the charge indicator lamp - power on both sides makes it go out. It's not on when the signals aren't in use because the circuit's incomplete (as it is for the oil pressure lamp when the sender is open); when the signals are in use, during the "off" cycle of the flasher there's a phantom ground applied to the pilot lamp through two of the four external lamps' filaments so it comes on - no dedicated ground connection is required for that functionality. Although the late flasher does have a ground connection it's just Teutonic over-engineering, a thermal flasher shouldn't need a ground to function (as evidenced by the Amerikinski flashers which work just fine without one).

A generic 3-prong flasher (550) is equivalent to the VW 4-pin (it just doesn't need a ground) and the 552 2-prong is like the VW 3-pin. Either one can be used, but if you want the pilot lamp and externals to flash in unison you need the 550.

Power in (+ on the VW flasher) is "X"
Flasher output (49a on the VW) is "L"
Pilot lamp (KBL on the VW) is "P"


4-pin flasher: http://www.vintagebus.com/wiring/Type_1 ... t_1969.jpg
3-pin flasher: http://www.vintagebus.com/wiring/1302_U ... r_1970.jpg

[CBDZ]

Marc,

Thank you for the response. What is understand is that I can simply do something like the attached sketch.



I guess my concern is the full current passing through the bulb in the gauge to acvtivate the signals, and then if the gauge bulb where to burn out, then the signals wouldn't work. Can I add another wire as a fail-safe as shown as a dashed line?

Also, just to clarify, this is in a fiberglass buggy, with a 100% custom wiring. I have a blank slate, but I want to keep the functionality of the idiot lights and indicators in the gauge. I am using a single pole, double throw switch for my signals, not an original VW.

Thanks.

[Marc]

Nope, not even close. The flasher power source does not go through the pilot lamp, it comes (through a fuse) from the ignition switch Term 15. The power source for the 3-lamp cluster on the speedo also comes from Term 15...it was unfused through `70, after that they started tapping it off of the fused power source for the gas gauge. Either way works, but if you choose to go fuseless don't use wire bigger than 18AWG (you'd want the wire to fry in the event of a short, to protect the ignition switch).


Look at the wiring diagrams I posted above. Disregarding the ground wire and those going to the hazard switch, use the `70 layout if you have a 3-prong generic flasher or the `71 layout if you have a 2-prong.

Here's another way to look at it if you don't need hazard lights, if you have a 3-prong (550) flasher X=15, L=54, P=K....for a 2-prong flasher simply piggyback the wire for the pilot lamp to the one going to the switch (L).
http://www.vintagebus.com/wiring/bug-60.jpg

[CBDZ]

OK, How is this? Unless the actual light and hazard switches are a major factor of how the power is distributed, this is how I understand what is going on.




large format image

[Marc]

That'll do it.
.
If you'll be using an aftermarket ignition switch with an ACC position, you could take the power for the t'signals, wipers, and brakelights from there instead - it might make the IGN contacts live longer if they weren't handling all of the auxiliary loads (pre`71 VW switches were intended to do that, a "boat" switch may not be)

VWs don't have any factory fuse protection for the ignition coil circuit so an added inline fuseholder for that wouldn't be a bad idea if the fusepanel configuration doesn't accommodate using one there for it.

The power for the pilot lamp cluster could come off either ACC or IGN, but if the former goes dead in the crank position you'd have no oil pressure warning lamp functionality until you released the key...not a big deal, but personally I like to see when the light goes out during the starting process.