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illumination issues - key switch - possible loose contact?

Posted: Sun Oct 07, 2018 12:43 am
by alviseven
Early phase one R8 hatch with D16 engine - I have on/off illumination with both the clock and the central console dash back light bulbs. It happens whether the side lights are on or not and it will happen mid journey and come back on again. Convinced it is not the clock illumination issues as I have soldered these already.
The issue will clear immediately the ignition key is unlocked and restarted especially if I pull key right out. The console illumination is a new effect and only recently noticed but even if I wiggle the key whilst moving it does not bring the lights back on but often the console lights come back on. My 250K car does not suffer this issue but my 190K car does so it sort of makes me feel it is not a wear issue unless I have been really lucky.
All illumination nearly always comes on with the start but then goes on at random. Often it will come back on at some point and for some time I did think this was a loose connection somewhere as its often seem to be back in use after a bumpy road but it is not directly related. Really makes me wonder if the contacts in the ignition switch are an issue but then I do not loose any engine ignition either.
So does anyone else recognise these symptoms? Anyone been in the switch behind the ignition barrel? Any other suggestions? Not looking forward to being in this area as removal is a pain I find.

Re: illumination issues - key switch - possible loose contact?

Posted: Sun Oct 07, 2018 2:37 pm
by Johnny 216GSi
Illumination is a separate 12v feed into the clock, radio and it's used directly to power the miniature bulbs in the cigarette lighter, ashtray, glove box and the rest of the console and binnacle.

I assume by "clock illumination" you mean the clock is dimming randomly with the lights off - exactly the opposite of the ignition barrel, which lights up with doors open, closed, etc. The clock has 4 connections - permanent live (to keep the clock circuit running so it keeps correct time), switched live (which turns on the backlight bulb), a 12v "lights-on" signal which is used to dim the backlight but not turn it off, and a ground connection.

If the clock is flickering off so you can't see the digits at all (but not losing time), that'll be the switched 12v feed that has gone faulty. If it's resetting to 1 o'clock then it's the permanent live or ground wires that have gone faulty. If it's flickering from dim to bright, then it's the "light's on" 12v feed which is also fed into the power ISO block on the radio to dim or illuminate he radio display.

The illuminated key barrel is different. It's supposed to light up on entry so you can see where to put the key in. I think that's controlled by the module in the centre console, at the bottom by the gear lever. I think it also controls the slow fade on the interior light. Mine does strange things occasionally with the slow fade, so wonder if these modules fail, get out of sync with the car door open/close signals, or just suffer from dry joints or connectors not making connection correctly.

Re: illumination issues - key switch - possible loose contact?

Posted: Wed Oct 10, 2018 12:15 pm
by g259fsg
Are you talking about the Multi-Function Unit (MFU) which controls a number of different things like intermittent wiper etc.? There is a test sequence to check operation.

Re: illumination issues - key switch - possible loose contact?

Posted: Sun Oct 14, 2018 10:09 am
by alviseven
no mfu is fine. it is switch related and only affects the clock mostly and sometimes the dash illumination. intermittent but nearly always correct when car starts but then with travel - motion - switches off but then will often come back on not necessarily when going over bumps just when it feels like it. You can almost will it back on by looking at it regularly! That bit is silly!

Re: illumination issues - key switch - possible loose contact?

Posted: Fri Dec 28, 2018 10:16 am
by alviseven
just an update really - seem to have sorted the clock which was strangely a loose bulb in its holder. Not the holder in the socket but the actual bulb in the plastic mount. Checked the spring type connections and the illumination of the individual bulb and replace - did not make a huge difference - put a new bulb in and not had issue since - have tried an LED version which was ok but too directional but did not flicker at all - then replaced the original bulb which immediately replicated the blink on off symptoms so have now binned it. Put a new filament bulb in the clock and not been off since.
Cannot recall what made me try this but have previously looked at the power feeds so was sure these were ok. Suddenly wondered if the bulb was iffy and so....
Think the issue with the key back light is perhaps as Johnny suggests a vague connection and lack of sync with something but is less of a worry
Now all I have to sort is why sometimes the headlights go off when I indicate at night and have to be switched on and off to make them come back on! Suspect a worn switch ......
Happy New Year