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I've decided to upgrade my dashboard knobs. I've seen a few cars out there that have at least one accurate bezel and knob @NTrav @Troy Sloan (assume either from Sierra Madre, Stoddard, etc.), and I was wondering what parts are necessary: bezel and knob or a whole new switch assembly too. Of course, the safest (and most expensive) way to go is to buy a new switch, bezel, and knob, but that quickly gets prohibitively expensive. I suppose the more fundamental question really is: will replacement 356A knobs fit the current VMC light and wiper switches?

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Find out what size threads you need to match and a rough approximation of the outside diameter of the bezel and maybe places like Summit Racing or Speedway Motors has something that you like and fits your threads.

Of course, there is Stoddards, Sierra Madre and Pelican Parts (all good, but pricey) for Porsche parts if you find that they’re metric or you’re trying to match something already there, and Bugcity.com among a slew of others for VW stuff if that’s what you already have.

@JoelP posted:

I've decided to upgrade my dashboard knobs. I've seen a few cars out there that have at least one accurate bezel and knob @NTrav @Troy Sloan (assume either from Sierra Madre, Stoddard, etc.), and I was wondering what parts are necessary: bezel and knob or a whole new switch assembly too. Of course, the safest (and most expensive) way to go is to buy a new switch, bezel, and knob, but that quickly gets prohibitively expensive. I suppose the more fundamental question really is: will replacement 356A knobs fit the current VMC light and wiper switches?

I was told all of the knobs on my car were from Sierra Madre.  I've only had to replace a fog light knob when it went MIA last year.  Everything else was on the car when I bought it so I don't know the actual part numbers.

I have small and large knobs in ivory color made in raw ivory ABS plastic.  They are center drilled at 1mm so they can be drilled and tapped for any switch thread.  Brad in the front office could get you an exact price bu I'd bet they are less than 1/2 of Stoddard.

I also make my own bezels but they are done to the threads I need and I have no idea what you have. The original bezels are specific to the Porsche switches and they are also chrome plated brass and cannot be retapped for another size.  Mine are aluminum and potentially could be drilled and tapped, depending on what size you needed.

WTF! Now my gauges don’t work immediately. I noticed this while I was checking my timing. I started the car and when to the rear to ensure all was good. When I looked up to see the tach, it was still at zero. Still, I adjusted my timing and shut off the car. I disconnected the battery, replaced all fuses just to be safe, reconnected the battery, and left. The gauges started to work after 10 minutes of driving. As soon as I stopped at a red light the tach dropped to zero, then randomly worked, then dropped to zero. After 15 minutes, the battery light came on.

Anybody had this happen? I’ve read other threads about similar symptoms, but they were on older cars or just dealt with only a tach flutter.

I checked everything under the dash and found TWO grounds that weren't attached properly. I remedied this. Sadly, this did not remedy the situation. No matter what, I start the car, but the gauges still don't work.

This is odd because it sounds like a loose ground, but I hadn’t driven or moved the car since it drove fine last week. That’s what’s so perplexing. Also, why the hell are the gauges working after 10 minutes of driving? Like the gas gauge and tach are temperature-based systems?

I'm at my whit’s end on this one.

Last edited by JoelP

Gremlins like this are almost always grounds. Every so often they're the + wire.

Check them all, one by one, make sure the connections are clean, the wires aren't getting pulled off by anything, the spade connections (or whatever) are tight on their tangs and the wires themselves.

Edit: You may need a dedicated hot wire to one or more of your modern newfangled gauges? Like doesn't the GPS need a moment to spool up & find its S? So: also make sure all the wires are plugged into the things they're supposed to be plugged into.

You will get it.

Last edited by edsnova

Thanks @edsnova  Haven’t touched GPS; that only affects the speedometer. It does show the mileage when I start the car, so that gauge is working. Hahaha! Ironically, I was telling someone the other day I plan on going to all mechanical gauges to avoid these types of stupid, needless problems: I owned classic cars all through my teens and 20s and never had these ridiculous issues. Tech for tech-sake is faddish TRASH!!  

That said, I haven’t unplugged anything but the headlight and wiper switches, which are fully back in, wired correctly, and working 100%. I had the foresight to take multiple pictures of the wiring before disconnecting each. I’ve learned that no owner’s manual means before and after pics are necessary evils.

I will start removing the gauges and labeling wires tonite.

Last edited by JoelP
@JoelP posted:

What is a “stay-on”? I Googled It and nothing came up. I’m wondering how to crimp those “tangs” mentioned earlier. All I know is that this is the worst designed electrical system I’ve come across. Who builds a car that loses gauge functionality simply by blowing and replacing a headlight fuse? I think even high school auto shop students wouldn’t make this type of blunder.

Sta-kon, or Stakon.

As for the rest of it, I'll just chalk it up to frustration.

Last edited by Stan Galat

Thanks @dlearl476 You are clearly miles ahead of me on this and have the method down. I think I’ll be taking a wiring class to redo this all over the winter, as I prep for my analog gauge install. These types of mysterious issues are not worth ignoring what I’m seeing under the dash.

@Michael Pickett I humbly request an opinion from the wiring wizard to the following question: aren’t proper electrical systems designed so that an issue in one part of the vehicle doesn’t infect the rest of the vehicle? If not, can they be?

Last edited by JoelP

Hi Joel, I suspect Ed and David are on the right track when they wonder if the problem has to do with the grounding. On my circa 2010 IM harness, all of the dashboard grounds were routed to a single connection to the chassis under the dashboard. If that connection to the chassis is bad or weak, it would cause the dashboard instruments to not work properly (same setup as the old 911s).

There are daisy chained +12v wires going between the gauges, but they are mostly for illumination. Your version of the wiring harness is probably different than mine since it's a different company, chassis, and much more modern.

To make a wiring harness fully fault independent so if one branch fails it doesn't impact any other takes a lot of fuses and relays. Just like my house breaker box, there are several things attached to single sources of voltage. It just isn't worth the extra fuse/relay space or the extra number of wires it would take to make a totally independent wiring system. It's all a compromise between how many wires you want to run around the chassis, the amount of current you can safely run through a single wire, and the impact on driving safety (if something blows, will it take out your headlights or kill the engine, etc).

I'm voting for a loose or broken ground connection under the dash. As call to the shop might get you better troubleshooting guesses. However, you've been on a mission to make this car meet your exacting vision, and have been making a number of changes to accomplish that goal. If I had built the car, I just might a little short on patience with trying to troubleshoot it from afar. I'd be nice to them if I wanted something, but I'm a softie.

Thanks @Michael Pickett I really appreciate it. I just got finished checking every wire under the dash, I had to crimp a few stay-Kons, but they’re on there.

I get the design issues. Thanks for that clarification. And yes, I tried calling VMC and left a message with Anna  at 10am PT, when I was stranded with a battery light on.  Never got a call back. As a litigator I always default to nice, as we all know that you generally attract more flies with honey than with vinegar. All I’ve gotten so far is silence. I guess we’ll see.

.

@JoelP posted:

.

...That said, I haven’t unplugged anything but the headlight and wiper switches,..

Joel, your car  may not be wired this way, but on Beetles, +12V from the battery was led to one of the terminals on the headlight switch and from there passed to feed various circuits in the fuse box.

My 2013 VS wasn't wired quite like that, but that tab on the headlight switch did pass voltage to other things not related to the headlights, so it's quite possible if one of the wires to one of those tabs is loose, other things may be affected. And they may turn on and off at seemingly random times as various loosely-fastened bits are jostled by the ride.

Also, with hand-made cars produced in small quantities, electrical teething issues like this are much more common when the car is new. Once everything is buttoned down solidly, wiring and fuses tend not to 'wear out' with time.

Do as you're being advised. Go through things slowly, methodically checking that each connection is sound no matter how 'solid' it may look.

Last edited by Sacto Mitch
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