Water Hound

My dash lights in the '04 C2 cab are driving me crazy (yes, it's a short drive indeed). Sometimes they'll turn on right away when headlights are switched on and other times could take up to 30 minutes to function. The digital guages, climate control, etc always work, It only affects the tach/speedo/analog gauge backlighting. The lights always work eventually but it's frustrating to say the least. No amount of jiggling the headlamp switch or ignition seems to work. Anybody seen this before?

DBJoe996

When this happens, have you tried using the cluster dim switch? Does it work to dim and brighten the cluster lights?

dporto

I think you need to open up the cluster, pull the bulbs, clean all the contacts and maybe replace the bulbs... Mine all work (at least I think they do) but they are sort of dim - and there are spots that seem like maybe a light is out or weak, so I'm planning on doing the same thing. I don't know when I'll get to it, but hopefully soon.

Water Hound

When the lights actually turn on then the cluster dimming switch works perfectly. If the lights haven't turned on there is no effect. Playing with the dimmer switch does not activate them.

When the lights finally do turn on they're on for the duration and don't flicker, dim or change in any way unless I manually adjust them with the dimmer switch.

All of the digital read outs - speedo, climate control, etc always work. It's just the analog gauge cluster lighting that is affected. Sometimes they'll work immediately and other days they may take up to half an hour to finally turn on.

Turning the car off, restarting, fiddling with the key in the ignition switch, turning the headlamp switch on and off multiple times, jiggling, wiggling and holding my breath all have no effect.

Water Hound

Are you suggesting that a weak contact for one of the bulbs may compromise the function of the entire circuit? OMG! This would be the equivalent of having the old string of Christmas tree light bulbs coming back to haunt me like the ghost of Christmas past. Remember the ones where one loose bulb meant they wouldn't work?

Oh well, I suppose it's time to learn how to remove the pod. Thank goodness for Rennlist and YouTube. Famous last words - how hard could it be?

dporto

Not necessarily "the string of Christmas lights" analogy (due to one bulb), but an intermittent ground to the light circuit would cause that effect.

5CHN3LL

Before you open the cluster, be forewarned that the cluster is a POS and a pain in the butt. The cluster "circuit boards" are printed on flexible substrate; just removing and improperly re-seating a bulb can tear or scratch the conductive layer. I have also managed to scratch off a decent amount of the tint/polarizing layer on the left-hand (odometer) LCD. The inside of the cluster looks a lot like the inside of a Commodore 64 - it looks like the 70's/80's in there.

Use a tool to reseat the bulbs if you do decide to proceed, either the Porsche tool or a bit driver the same size as the bulb sockets.

I will be removing and disassembling my cluster for the 4th time tonight to try a new dimmer; if that doesn't work, it goes to the indy tomorrow for diagnosis and repair.

Unless my luck changes with the dimmer, all I have done in the weeks of DIY troubleshooting is to further damage my cluster...

OP, my issue seems similar to yours. When I turn on the headlights and the ambient light detector notices it's dusk or dark, my cluster lights briefly - 5-30 seconds - work as expected, then start pulsing/flashing. If I allow this to continue, a tendril of smoke will eventually trickle out of the cluster. I can't find any scorched PCB, wiring, connector, or any other indication of where the short/issue might be. The dimmer is a hail mary, mostly because the part is cheap.

Water Hound

dporto - An intermittent ground sounds like a reasonable possibility and one I am not qualified to trace.

5CHN3LL - Opening the pod also sounds like trouble waiting to happen. Can't believe you're still trying to find the smoke issue. I think I first read about that problem a year or more ago. At least no smoke on my end (yet).

Sounds like a job for the professionals because electrical and my talents just don't match up.

Rewards77

Hi, I’m having the same issue on my 04 GT3. Did you get this solved?

Thanks
R

Subourbonite

I see that the OP has an 04 996. Curious what years the rest of you have.

As I understood, the earlier 996 gauge clusters were bulb based while the later 996’s were LED based. Here have been several write-ups on RL and 6-speed on updating LEDs and even color change, which I may tackle with the quarantine not letting up anytime soon.

Rewards77

Thanks Subordinate, 04 GT3 and I have the exact same symptoms as Water Hound. Digital displays are not affected. Only the analog dials. I was driving with the lights on during the day yesterday and at some point the dash lights began to work. When I returned home I switched the lights of an on and the lights did not come on again. I feel that it could be an earth, a bad connection or the light switch itself.

Subourbonite

Haha! It's actually SuBOURBONite...ahhh the smoky undertones...but thanks there boss!

I think my question was to differentiate lighting (LED vs bulb) technologies not so much display (LCD vs analog gauge) technologies. Again, my understanding...and I may be wrong...is that early 996 used standard bulb lighting to illuminate the dash where later 996 used LEDs to light the dash. I'm not sure whether the change followed .1 to .2 facelift.

Thus my question of model years as we talked about bulb replacement. My thought was that 99 and 04 MYs have different lighting technology behind the dash, so if having the same issue, that issue may be less bulb/LED based than something else.