Dash Lamp Replacement Question

[Paulporsche]

I want to replace my current Philips 12829 12v 2w dash lamps with Sylvania 3893 12v 4w lamps. I see these are interchangeable. Is there any issue due to the increased wattage? Do I need a relay or a change in wiring or fuses? Per Ohm's Law I wouldn't think so but I'm just checking.

Thanks.

[acme911]

Have you considered LED’s?

[Trackrash]

I guess you may be OK, due to the fact that you can adjust the brightness.

There was a tech article about adding a fuse to the dash light circuit as there have been fires known to start if there is a short.....

From my experience Porsche used the smallest wire size possible in most of their electrical circuits in the older cars, so let us know how it works out for you.

[Paulporsche]

I may just go with Engelbert's LEDs after all.

[pete3799]

You won't be disappointed with the LED's.

[acme911]

I just went full on LED's inside and out. Last page in this thread:

A Werk in Progress

[86 911 Targa]

Originally Posted by Trackrash

I guess you may be OK, due to the fact that you can adjust the brightness.

There was a tech article about adding a fuse to the dash light circuit as there have been fires known to start if there is a short.....

From my experience Porsche used the smallest wire size possible in most of their electrical circuits in the older cars, so let us know how it works out for you.

^^^^^
Here are a few items for your review.

Fusing & relays was not Porsche's finest hour on the 3.2 & prior 911's.

Best,

Gerry

[MBAtarga]

Is there an official Porsche part number for the fuse assembly to install on the dash wiring?

[Paulporsche]

Thanks for that, Gerry.

Nice "werk" Acme.

[famoroso]

I run bright white and classic white LEDs in my two cars. They are both great. The classic version are pretty white, but not as harsh as the bright white.

[Paulporsche]

Just placed an order to Engelbert for the Vintage White. Anybody know how long shipping takes to MA?

[spuggy]

Fuse the interior light circuit, even if you don't fit LEDs. Good quality ATO fuse holder is like $5.

Doubling the load on a circuit responsible for many dash fires over the years? Not a great idea.

Usually need to fiddle with BA9 LED replacements; the socket isn't polarity sensitive, but the LEDs mounted in the base are. Many larger LED replacements work either way, but no-one seems to bother for these smaller bulbs (very likely a packaging issue).

If switching out the fuel warning lamp, run the fuel down until it's lit first, much easier to get the correct polarity... It is very nice to get a deep red warning light instead of the faded pink too...

AFAIK, all bulb-replacement LEDs have a load resistor built in (to reduce the car's 12V to the 1.8-3.3V LEDs operate on), but some LEDs intended for "smarter" cars have more load - either to simulate a real bulb and avoid "bulb out" warnings, or for flasher bulbs intended to operate with standard relays (as opposed to replacement LED friendly relays).

Those resistors can negate some of the benefit of LEDs, as they load the original wiring just as much as bulbs. They won't melt plastic carriers (e.g. in the heating panel) though...

Originally Posted by acme911

I just went full on LED's inside and out.

First off, props for the middie love

Secondly - really? I tried that years ago - just for the interior... Hit a number of snags...

Did you find festoon LED replacements for the courtesy lights that aren't polarity-sensitive? I tried to - but failed.

Without that, least on my car, seems that you can't have the courtesy lights work on both a) the door opening and b) when you switch them on manually. Filaments don't care about polarity - but LEDs do, and I have to swap them around 180 degrees to get the "other" circuit to work...

Also, AFAIK, the generator warning light needs the resistance/load provided by the wire filament to perform the essential task of making the alternator produce current (part of the exciter circuit). More importantly, pretty sure that current has to flow both ways through that lamp. So wouldn't respond too well to an LED there, as they only pass current one way...

I also noticed funky "ghosting" on one of the flasher repeater circuits when I used LEDs for those... Someone figured out why on an old thread, I think...

Originally Posted by famoroso

I run bright white and classic white LEDs in my two cars. They are both great. The classic version are pretty white, but not as harsh as the bright white.

Yeh, I thought I'd prefer the bright white and fitted them first. They were novel for a very short while. I tried hard to like them - but classic suits the car much better.

Strikingly better illumination though; very even - and much brighter.

I still want to add a proper LED dimmer so I can turn them down until they're like watch dials (for unlit roads), but the "sort of" dimming that LEDs give on the stock rheostat (until they cut out completely at ~60% or so of "full bright" as they drop out of their operating voltage) will do for now.

[acme911]

Originally Posted by spuggy

First off, props for the middie love

Secondly - really? I tried that years ago - just for the interior... Hit a number of snags...

Did you find festoon LED replacements for the courtesy lights that aren't polarity-sensitive? I tried to - but failed.

Without that, least on my car, seems that you can't have the courtesy lights work on both a) the door opening and b) when you switch them on manually. Filaments don't care about polarity - but LEDs do, and I have to swap them around 180 degrees to get the "other" circuit to work...

Also, AFAIK, the generator warning light needs the resistance/load provided by the wire filament to perform the essential task of making the alternator produce current (part of the exciter circuit). More importantly, pretty sure that current has to flow both ways through that lamp. So wouldn't respond too well to an LED there, as they only pass current one way...

I also noticed funky "ghosting" on one of the flasher repeater circuits when I used LEDs for those... Someone figured out why on an old thread, I think...

Regarding LED’s. Like you I tried out some of the first generation LED’s on my Dodge truck. Disappointed with problems, I chucked them.

The Festoons were purchased on Amazon...Zero problems.

As recommended by others, I did not replace my turn, generator and fuel reserve lamps. Carmagic’s Kit comes with the high beam, parking and one extra bulb. Very nice!

With my SpokeLED kit I added the LED specific flasher relay. This solves “ghosting” flashes. Prior to using Spokes system I tried LED bulb swaps. These required the use of load resistors and were better than incandescent, but still not anywhere near the amazing output of Spokes!

My take away from swapping over to LED’s is that the latest generation of lights have solved a lot of the earlier glitches.