Ed Scherer

Late to this thread, but I can't resist LED topics.

It's of greatest use for '89 and later cars, but much of the material in Converting Porsche 928 Interior Lighting to LEDs applies to earlier cars as well (and I think that includes the pod switch backlighting). Look for the section entitled "Pod Switches". Also note that to maintain the proper two-intensity-level backlighting for most of the pod switches (to indicate on/off state, etc.), you will need to add resistors. That procedure is described in the document, too.

For pod switches, I recommend the "#74 Super High Power 1 Watt Super-Charged LED Bulb" from Autolumination. They've been flawless for me, and come in all the right colors. There are, of course (as already seen in this thread), other LED bulbs that should work, too. I tested quite a few different bulbs at the time I was seeking "the best" bulb, and at that time, the above-mentioned bulb was the best one I found. It's possible that newer alternatives might be better. I just don't know.

As Sean already mentioned, getting really good photos of the results isn't easy. That said, here are a couple of my '90 928 S4:








Some earlier bench testing:




Stock on the AILD-1 PWM dimmer modules is low right now (I think there are just two assembled modules left), but I expect to build another batch within the next few weeks.

Alan

You don't seem to have read and understood what I said about how these are suposed to work. Remember you cannot hope to fix something if you don't understand what the normal behaviour is supposed to be... ? https://rennlist.com/forums/11371199-post13.html

When you say dim - is this variable with the rheostat? it should be, if not there is an issue. All the switches I described should have the same variable low intensity mode - even at max brightness it should be much lower than the activated illumination level. This is accomplished with built in resistors (in the switch), however these resistors are sized for the incandescent bulb currents - when you switch to LEDs the resistors are far too low a value for the lower LED current levels - this leads to little difference between the activated & variable levels. The PWM dimmer helps some here - but not on brighter settings that most use - so you still need larger value resistors in series on the 58 input of every switch.

If the bulbs work OK (bright) in activation mode then they work OK - nothing more to do. You can also test the variable low level illumination for them directly by connecting ground to terminal 31 and 12V to terminal 58 on the switch (removed from the circuit) - this is just the low intensity mode.

For this not to work right you pretty much have to have a wiring problem to the 58 terminal.

If your reset switch only works when you press it that is quite wrong - should be on all the time with lights on, and it should have no activation mode illumination.

Note that the variable illumination mode via the rheostat only works propperly when all the bulbs it is intended to drive are ALL actually connected to it.

Alan

Ladybug83

Yes it is variable, it goes from dim to dimmer (off) with the rheostat. All of the other lights dim with the rheostat as well, they are just brighter.

" If your reset switch only works when you press it that is quite wrong - should be on all the time with lights on, and it should have no activation mode illumination. "

It is on all the time when the lights are on, it's just not bright like the others.

Wasn't intending to switch to LEDs until everyone suggested that it would fix the problem. I recently changed out all of the gauge and pod lights with new incandescents. Definitely won't be taking it all apart again anytime soon. Just want to get these two bulbs up to par if they are not.

Keith Coe

Sean: I want to add this to my "to do" list when I come see you in June (time permitting, of course)!

Alan

None of them should be bright - thats really not the point (and is counter productive) - they should just be visible enough you can tell the function by looking at the icon. They also should be dim enough even at the brightest dimmer setting that the switch activated bright mode is easily distinguished - it may be your others are too bright..?

The hazzard seems rather brighter because the red field is illuminated unlike the other switches where only the icon is illuminated - the headlight switch will always be at the bright end of the dimmer range since its directly fed, the fog & rear defrost should be similar, the reset may look the dimmest because it has the smallest icon area illuminated...

Don't create a new functional issue by trying to make these too bright.

Alan

SeanR

With or with out dimmer. I've got everything else in stock I believe.

Ladybug83

I'm just trying to get them all consistent. The others are not too bright, as far as I can tell, they're all normal except for the reset.

I guess it is what it is. Thanks for all the input guys.