PC-85-928S

What happens if all the interior lights are not converted to led?
does the dimmer control non led lights as well?
or is this for a full conversion?

Petza914

In my car, it made all the non led bulbs very dim. Think they all need to be converted to leds for this to work well.

Alan

LEDs need to be dimmed a different way to incandescents - what works well for one is always non optimal for the other. So if they are all going to live with the same supply/dimmer its best to make them all the same type (or you could have 2 supplies & dimmers - BUT usually this is a wiring & functional/ergonomic nightmare!).

Alan

gearctrl

Hey Ed, would love to pick up one or two from you in the G3 configuration. I have been watching your site for the last few months for availability. Any chance these will be back?

Ed Scherer

Check again.

Also, since you mentioned configuration G3, you're probably not needing it for a 928 application, so I'll warn you to make sure that your rheostat is electrically isolated if it's part of some kind of a headlight/instrumentation light switch assembly or that you can modify the assembly so that it is. Make absolutely sure neither of its terminals is connected to anything else — especially 12 V — at any time. Some rheostats are part of headlight switch assemblies that have one side of the rheostat internally (inside the assembly) connected to something else (e.g., the headlight/parking light switch). If that's the case, you need to somehow modify the assembly and break that connection (and possibly add a terminal if both sides of the rheostat didn't have accessible terminals on the assembly). If you can't do this, the AILD-1 won't work for your application.

Jballard2140

Hi Ed,
I recently purchased a 1989 S4 that has had the dash lights switched to LED. Since the day I got the car, the gauge lights have flickered and I have had a few other lighting glitches. I started digging around under the gauge pod and removed the dimmer wheel and cleaned it up, re-installed it and hoped this would fix the flickering. It did not. I bypassed the dimmer wheel by connecting the wires from the dimmer together, but it did not affect the flickering. I dug deeper under the dash and found what turned out to be your clever LED driver. After this discovery, I searched the forums and found my salvation in this thread! I have read this thread from start to finish and your incredibly well documented walkthrough (incredible work). My next moves to fix the flicker are checking grounds. I am hoping I don’t need to remove gauge cluster. I am curious if the grounding of your device needs to be on the large grounding post under the steering wheel? Mine is grounded to some bracket that might still have paint on it or is not grounded to the chassis correctly. Fuses and relays have been swapped out for new ones. I also saw underneath the pod that the purple(?) wires to the wiper speed wheel have been disconnected. Any other ideas on how to fix the gauge light flicker?

Ed Scherer

Hi. I'm preparing for a meeting in a few minutes, but can get back to this later today. I can then give you some troubleshooting tips to get this diagnosed and resolved.

Until then, can you tell me:

• What the AILD-1 dimmer module LEDs are showing? Is the red one (which generally indicates faults) illuminating at all, and if so, what pattern? And is the blue one (which is just a monitor of the output) flickering along with the rest of the instrumentation lighting?
• Are all of the instrumentation lights that are dimmable flickering (e.g., backlighting for main instrument cluster, all big ***** other than headlight ****, A/C controls backlighting, etc.), or just some of them?

That would be helpful to know.

Also, any good ground should be fine for the AILD-1.

Jballard2140

I will try to post a video of it, but the module red light is blinking in a repeating 5 blink pattern.
Blue light on the module seems steady.

Currently, all of the pod lights, clock light, A/C panel lights, O button and central lock button work normally (though they wont dim since I connected the light dimmer wheel wires).

Ashtray light and drive selection indicator lights not working at all.

My interior lights were giving me problems, but I traced it to the door post switch sticking and causing variable times for lights to come on or time themselves off. Currently, all interior door and dome lights work.

The edge of door lights do not come on and I am getting a driver side parking light failure every time I turn on the headlights.

Ed Scherer

Your videos are helpful; thanks for providing them. You might have two separate things going on here.

I'm sharing the below for the benefit of others troubleshooting similar problems in the future. But I'll follow up with a private message so we can take the additional steps needed to resolve suspected problem #1.

One thing to note is that videos of flashing LEDs (even at high speed, as occurs with LEDs that use drivers — including PWM circuits — where the flashing isn't usually perceptible when just looked at because it's faster than our eyes can detect) can be misleading due to the frame rate of the video.


Suspected problem #1: Loss of configuration in AILD-1

Reason: From video IMG_0104.MOV, it looks like the AILD-1's fault LED (the red one) is showing a "10 Hz rapid blink, 1 Hz on/off, repeat..." pattern.

The following information off the build label on the AILD-1 would help confirm this diagnosis. Could you provide it to me?

• SN (serial number; in plain text under the same information encoded on bar code)
• Pgm (firmware/program version)

It's likely that the unit is running version 1.0 firmware (i.e., that the label will show "Pgm: 1.0"). In version 1.0 (but not 1.1 or later), the unit had a window of vulnerability where it could lose its configuration — which is stored on the microcontroller, along with the firmware itself — in certain power on/off scenarios. If that's the case, I'll send you a replacement IC with the latest firmware (version 1.2) to install; see the AILD-1 Microcontroller Replacement Guide.

In this failure mode, the AILD-1 goes into a failsafe mode with a fixed output level, independent of the rheostat's position.


Suspected problem #2: Failing backlighting LEDs

Reason: From video IMG_0103.MOV, it looks like you've got more than one failing LED emitter, probably on different bulbs (each of the four bulbs probably has five emitter chips)

As with many LEDs, typical failure modes include immediate total failure, flicker for a while and then totally fail, or just flicker. And some chips have multiple emitters on the same chip and just one fails, so you just get a slight loss of emitted light (or even slight flickering).

This, unfortunately, will require replacement of the bulb (probably 194 LED Landscape Light Bulb - 5 SMD LED Tower - Miniature Wedge Retrofit - 95 Lumens - Natural White (superbrightleds.com) or equivalent). And that means — sorry — removing the instrument cluster.

Useful references for this: 15 minute instrument pod removal update and instrument light bulbs for an OK price (another thread here on this forum) and Converting Porsche 928 Interior Lighting to LEDs (a document I wrote many years ago).

If you are indeed dealing with failing bulbs and decide to replace them, I'd suggest replacing all of them (the four "wedge" 194 backlighting LED bulbs, to be clear). LEDs don't like heat, and the instrument cluster is a really hostile environment for them (often hot car anyway, and then very little airflow inside the cluster).

If you're reluctant to take this on yourself, perhaps you can find someone in your area who can help. Luckily, you're in a part of the country with a high 928 density and plenty of enthusiasts!


I'd suggest tackling problem #1 first (if my diagnosis is correct, this will at least restore dimming functionality) and seeing how far that gets you.

Ed Scherer

These are likely a bit off-topic in this thread and will require separate diagnosis; I'd suggest searching existing threads and/or starting a new thread for these issues. Some are rather common problems.

Jballard2140

Ed,

I can’t thank you enough for your expansive reply. I would definitely be going down the wrong trail without your advice. As you can see, version 1.0. Please let me know what I would need to do to update firmware or hardware. It looks like I’ve got a project to get started on this weekend.

Are the gauge bulbs upstream of the ashtray lights or the PRND32 lights or is that a separate problem? From what I have gathered on other threads, the taillights and door lights seem to be on the same circuit.

Ed Scherer

Glad to help! Thanks for the build label photo. Perfect. Hmmm... Serial number 13. So superstition enters the picture, too.

Check your private messages for next steps on AILD-1 microcontroller IC replacement.

Please do start a separate thread on those other issues. More people might step in to help, especially those who have dealt with those problems. I'll help, too, time permitting.