MainePorsche

Guys,
The new issue is illumination to the HVAC controller, analog clock, the pod flasher switch, odometer reset switch, rear window defrost/defog switch, fog light switch suddenly vanished. Dash lights and cigarette lighter illumination OK. Rheostat function fine as I serviced it over a year ago. Clock functions. Fuses 7 and 44 fine.

Here's where it gets interesting.
1. When pushing in/operating the flasher, rear window def., and fog light switches they illuminate. They don't illuminate at 'rest'. The odometer reset does not illuminate at all, but checked bulb with a 9v battery, and it's good.
2. My AC clutch now engages with the light switch on in the current condition described above. It has not for some time, and I had worked it through and my Dx was a defective HVAC board. I was planning on replacing the HVAC controller and tying the HVAC head relay to power an industrial strength external relay to feed the compressor clutch via Wally's write up. I opted for this method for I also will do (and have done) significant LED work to the HVAC unit (I did my LED/FOF work BEFORE this light switch/AC gremlin). If you wish see these 2 posts I generated on this issue.
https://rennlist.com/forums/928-foru...-relay-xi.html
https://rennlist.com/forums/928-foru...cky+AC+problem
3. Another interesting finding is when I depress the fog light switch to a point just before the relay kicks, and the lights go on, the HVAC controller illuminates. If I push it in to the point where it holds, the HVAC illumination goes out.

WTF is going on !
I now have one old gremlin cured - AC issue with the lights on - only to have a new one with this illumination failure.

Thanks in Advance for your Wisdom
Craig

PS: I know this is a tedious one, but this is a real Holy Sh_t issue.

WallyP

First thing that I would try would be to hook a voltmeter between a good chassis ground and the brown wire on the misbehaving circuit. If there is voltage on the brown wire, you have a faulty ground.

MainePorsche

Hi Wally.
Regarding the loss of illumination, there are multiple circuits and multiple ground points (ie Flasher is MP IV, Clock MP V). The only thing in common is their Black/Blues.
I could see if I lost illumination in one circuit - but so many - and without loss of function (ie clock). Would this not speak to multiple, simultaneous failures of 'browns' ?

SQLGuy

I would guess that point 3 means that, when partially depressed, the switch is coupling the illumination for the engaged fog light to the dimmer-controlled black/blue that everything shares. If you jumper 12V (through a fused line) to the black/blue I would guess that either everything will light up, or everything up to a break in the black/blue will light up.

MainePorsche

Which black/blue line would you tie into ? Any, or specific, such as proximal at the rheostat ?

SQLGuy

Depends what you have easy access to. If 12V at the rheostat lights everything up, then you know you've got a problem at the rheostat or in its supply line. If it lights nothing up, then you can try again with a wire at one of the known working lamps, to see what does and what does not light up.

MainePorsche

Wally, SQL thanks a lot.
Going to go through the diagnostics a little later.
Just one quick question - never mind - the WD just gave me the answer.
Thanks again.
Craig

MainePorsche

Well, here it is.
Only 2 Masse Punkt involved, MP IV & MP V - both, and hence all 'browns' to them zeroed.
The Black/Blues is where the 'blues' were.
According to the WD, one Black/Blue from the rheostat feeds the dash lights [E 23], and the other Black/Blue feeds illumination to the pod switches and the center console (except the cigarette lighter which is still fed from the dash Black/Blue... go figure... Porsche).
The defect was under the pod in a Black/Blue deep in the vicinity of the ignition switch - obvious get when I went to work on it in the day for there was 'shiny' electrical tape - the 'positive shiny black tape sign' as we would call it in Medicine. Under this tape the Black/Blue was simply twizzled together and unattached.
After my curative repair, all lights back to original, with the AC clutch not engaging with the light switch on. A sigh of relief - at least there's no mystery here, and illumination back to normal.
Thanks SQL and Wally for your attention.

MainePorsche

Took her out in the sun for a drive on this nice Saturday afternoon. Got in the garage and went to close up as usual, and now I'm blowing fuse 14 for the sunroof.

Unbelievable.

When is this electrical goodness going to end.