algie928s4

On my 88 S4 the digital display only fully displays in the centre, at both ends it is quite faint. However when I get a TYRE PRESSURE WARNING it illuminates perfectly when driving-(aftermarket wheels).
Can anyone point me in the right direction? Do I need to clean contacts inside the pod, replace LED's or bulbs?
This only happens on the left hand side LED display if that helps/narrows down problem!

Ed MD

Are you sue that yours is an 8'8, as i thought that the digital displays didn't start till 89? At least my 88 isn't digital. Ed

ROG100

If it is the digital display you need to replace the LCD bulb/s that are burnt out.
Remove the pod and seperate the cluster.
If you need pics of what and where I have my 89 cluster out at the moment.
Let me know.
Roger

algie928s4

Yes it's an 88- first registered 7th October 1988, must be the overlap for this.
Roger if it's more or less straight forward I won't need pictures, but I am now very curious about the bulbs or should I say how the LED works if it requires bulbs- or I'm I just posting my stupidity to the world????!!!!!

bwebb77

When it comes to Porsche's, there are no stupid questions. Better safe than sorry. These(we) people are very understanding.

ROG100

Here are pics of the cluster with the PCB back off.
You can see the 8 LCD bulbs, 4 white and 4 red.

There is also a seperate unit that I beleive gives the background lighting to the three readouts. Is it faint or showing lines?
A picture would help.

Hope this helps

Vilhuer

10/88 registration do not exclude possibility of it being '89 model year. '89's were made between 09/88 and 08/89. Car manufacturers model years are not same as calendar years. To be sure you'd need to check VIN's 10th digit. If it's J, car is '88. If K, it's '89. I would expect it to be K and last 5 digit's of VIN to be in between 40061 and lets say 40300. This would mean early '89 ROW model.

algie928s4

VIN No is indeed 10th digit K however last 5 are 40311, thanks Erkka you've just gave me some more bragging rights against my 928 buddies- is there any significance to the 40311- 11 more than your parameter?
The thing I don't get is if the display reads 60 MPH for example, it's made of of a series of dots- how can the display transform a single bulb into series of dots to enable a display of 60 MPH??
As usual the 928 throws up more questions the more you dig/ask it's this kinda thing that intrigues me about this car.
However back to the original question- the display is very faint on the left side and gets stronger towards the right so if I was to describe as 0=NIL and 5=NORMAL the display would read:-
0012345555 is that any clearer?
I've ordered all the bulbs listed on the PET-in for a penny in for a pound so I'll take the POD apart on Tuesday and give it a thorough service .

Vilhuer

Not really. It only means Porsche did few more '89 model year cars early on in production than what I expected they had done. 300 came from calculation:

(ROW '89 model max VIN - Prototypes) / Months = Average montly production
(2488 - 60) / 12 = 202.33

So on average Porsche made 202.33 ROW 928's every month during '89 model year. VIN's 40001-40050 were reserved for prototypes and 40051-40060 for special cars. First production model was VIN 40061. Because of this, 60 needs to be subtracted from largest ROW VIN 42488 to get number of normal production cars. 2428 devided by 12 month production is about 202. Next thing is to add 60 back to get VIN number again. I added some margin by rounding out estimate from 262.33 up to 300 but it seems it wasn't enough. Possibly factory started week or two earlier than beginning of 09/88 and/or they did more cars on those early production weeks than some time later.

Way those displays work is that there is two transparent films and liquid in between them. When electric current is applied to this special liquid it turns opaque on those spots where current is aplied while other parts of display still allow backlight to come through. So each dot in display is point where electricity goes through the liquid. There are few bulps at the the back and if one of them is burnt other end of display is darker than one where bulp is still working. More than one bulp lights up entire display. When you change all bulps I'm sure you'll notice it's much brighter on both ends. Old bulps are likely to be noticeably dimmer than new ones.

algie928s4

Thanks Erkka

gf261

My 89' shows production date of 9/88 as well.

Alan

Roger,
Since you've done a bunch of Pod things (thanks for these photos) what do you recommend on bulb swap out - did you replace all yours? Looks like there are 10 clear bulbs (w/ yellow bases)(for an auto - but assume its just 5 for a manual?) 4 of these for the LCD Part# 999.631.027.90?

Then there are 4 red bulbs (w/ yellow bases) of same size for LCD part# 928.641.982.02

Seems there are then 16 clear (blue base) bulbs shown (but also 5 more blank/dummy cutouts - might these take additional bulbs depending on equipment?/year?) Assume these are part# 928.641.982.04

Are the 4 big black plastic plugs the back of bigger similar bulbs for the pod illumination?? are they part# 928.641.982.01 ?

I was thinking to replace everything while I'm in there but it works out kind of expensive from the big 3 for all of these - approx $130 of bulbs? Did you find any alternate/equivalent bulbs? change them all? do any of the big 3 offer a complete bulb package for this (and yeah I do know you folks'll be happy to sell me everything I need...)

Thx,
Alan