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Install New GPS speedo in MkI VW

1449 Views 2 Replies 2 Participants Last post by  cajun100
I have spent some time now reading the amazingly valuable discussions on this and other VW forums. Incredible how much I have learned about my 35-year-old Convertible purchased new in Germany. Appreciate the info -- ALL of it.
Here is my specific problem (challenge):
I want to use a new GPS speedometer and forever forget the original mech cable thing. The new speedo has nicely built in turn signal (L and R) indicator lights and a hi-beam indicator.

The issue I am facing is how to connect from the existing wiring to enable using the L and R on the new gauge.

--- could I simply splice one of the communication connections (for example, from the turns switch on column) ??
--- could I split the incoming to dash wire in some fashion to have L and R indicators work instead of one green bulb on dash?
--- could I splice the actual switched power wires to the 4 signal lights and have the new speedo pick up the pulsed signal there?

I am almost finished with successfully waving good-bye to the rapidly dying blue foil circuit serving the instrument panel. A new tach was easy. With a solution to the R-L turns "pulse" and new external water temp and oil pressure gauges, I will be updated and happily driving my dear Convertible for another ----- years.

If anyone has already worked this out, please refer me to that information (Briano, specific thanks to you for your dedication to the members over the years).
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Didn't see this until today, sorry...
You can't use the input from the stalk as that is uni-directional as it is picking up the power from the Relay, as the power for both turns, and the 4-way.
You would be better served in using a wire from the left or right side bulbs that run from the switch as that would be the power to light the bulbs.

That would be the black/white (left) or the black/green (right) you may be able to get them out of the Stalk as they are sided that way. When the flasher is selected then you would have both flashing as the 4-way powers Both sides.

VW went cheap, and only used one signal path to power the bulb and that was the input side or ground side of the picked relay to power both the 4-way and the left or right with but one wire and one bulb...albeit they did use 2 power sources for the separate sides as the low fuse for the 4-way and the higher fuse for the turns.

You still may see the wonky glow of the turns if you short out that wire, which is why I always suggest to heat shrink that thing to prevent the dreaded I only moved my switch why do my turns only glow..(because the power wire shorted to frame taking out the higher fuse.).... The black/blue wire:

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All of what you said I have considered and I can live with the indicator(s) both flashing whether L or R selected. In fact I have a new GPS speedo (finally !!!!! no more lost cable gear) and it has both indicator arrows. These will flash together now.
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