Auto Dimming Rear View Mirror

[HPsauce]

Originally Posted by ainarssems

It's about 45 dg anti-clockwise on PF cars to undo it but take care.

Well, it turns out it's 60 degrees anticlockwise on mine - the mounting is hexagonal.

Once rotated to the release position it came off very easily.
I had a moment of inspiration and remembered one of my "oldies" tools in the kitchen - a "BOA-CONSTRICTOR" designed to help remove difficult lids on jars.
See: http://www.amazon.co.uk/Miscellaneou.../dp/B0001J0456 it even refers to use on cars there.

It has a rigid plastic handle and a tough rubber strip that you wrap round the "lid" then feed back into a slot on the handle. Applying rotational pressure locks it firmly. Ideal for rotating the mounting pillar as it does no damage at all but gives a superb grip.
As they say "Every home should have one" (and every car mechanic)

Now I need to look at the power supply for the auto-dim version.
I'd still prefer to take it off the sunroof (access comments anyone) but.......
I've got all the floor mats out to dry the interior as stage 1 of dealing with the flooding, probably due to clogged evaporator drains.

[HPsauce]

Originally Posted by HPsauce

Now I need to look at the power supply for the auto-dim version. I'd still prefer to take it off the sunroof

Well it's a bright sunny day today so I can see what I'm doing.
Got the lights/sunroof panel off - unclip transparent bulb cover, remove 2 recessed screws by the bulb and it just unclips easily.
(as described in the drivers manual, as I've just discovered )

But inside it, ignoring (for now) the wiring for the phone (mic) and sunroof controls there's a 5-core multicoloured lead to the interior lights.
(there's also a thin, I think red/black, lead that meanders around with no obvious function/connection - sun visor mirror lights probably)

I'll post up the colours shortly, but meanwhile I'm going to have a bit of an "investigate" with my multimeter on the interior light connection.
Logic says you only need 3, not 5 - 12V, 0V and door open.
(Unless anyone knows what they're all for and can save me the effort.

Edit: The colours, from left to right are:
Red with blue (or purple?) trace
Green with blue trace
Brown
Brown with yellow trace
Brown with white trace

[HPsauce]

Results of investigations:

Originally Posted by HPsauce

Interior light connector from left to right:
Red with blue (or purple?) trace = 12V permanent
Green with blue trace - switched
Brown = 0V permanent
Brown with yellow trace - switched
Brown with white trace - switched

The switched connectors all switch together, 12V normally, dropping to around 1V if any door is opened. Ignition/lights have no effect.
So no use for the mirror.

The sunroof motor is more promising however; bit tricky to disconnect due to lack of space.
Fat Red/white = 12V
Purple/black also 12V
Fat Brown = 0V
Red/yellow = 12V when ignition is on (with a retaining delay I think), 0V when doors are locked.

I don't want to disturb the "fat" heavy-duty cables to the sunroof, so I'll probably take 12V from the sunroof red/yellow and 0V from a screw (there's a couple of suitable holes in metal that test OK) or the lights (brown) using the dreaded Scotchlok's.

No doubt some of you perfectionists will be squirming in your seats now.

[HPsauce]

Job done, very pleased with the result. Works perfectly.

Biggest problem in the end was actually getting the lead from the mirror into the space above the lights to connect it up, it's a bit tight and though I could get a big cable tie through to pull with the plugs kept snagging. In the end I fed it unterminated and fixed the plugs (just bullet connectors) once in place - very little spare wire to work with though.
(I did take 12V from the sunroof and 0V from the interior lights in the end. )

[HPsauce]

Originally Posted by HPsauce

Works perfectly.

And proved handy just now.
Already freezing outside, headed off to the station (3+ miles) and was stuck behind a big supermarket truck at 30mph on a narrowish country road. No possibility of overtaking anywhere.

Some t**t in a big 4*4 caught us up and decided to drive as if I was towing him.

[Nollywood]

Glad to see you got it working well.

At some point, I'd like to replace mine with one from the C5 Allroad (probably on other C5 models). There was the digital compass option, pretty cool.

[HPsauce]

A couple of things I've noticed after rather more use:
1. The interior lights coming on (e.g. dropping off a passenger) make it go very dark very quickly. If you're using the interior mirror to check behind before moving off you need to wait briefly.
2. In the (admittedly very rare) situation of someone overtaking you on the motorway at night the darkest is actually as they get close and move out of your view. I think this is due to the direction the rear-facing sensor points in, i.e where the mirror is pointing which is obviously half-way between rearwards and towards your eyes, so significantly to the offside.

Oddly I haven't noticed either of these effects on the similar mirror in my Ford Focus, though the rear-facing sensor on that is recessed below the mirror rather than behind the top of the glass. And being a hatchback there's probably more bodywork blocking light from overtaking vehicles. (it also has a handy "off" button)

[Nollywood]

^^^ Interesting observation, HP.

This brings me to another issue - how do those with really dark tints on the rear (sometimes limo tint on the rear screen) fare with auto-dim (or rather lack of?) Because one could argue the rearview mirror doesn't suffer from as much "glare" as would be achieved with a stock rear screen.

But that means the door mirrors won't dim either. Has anyone with dark rear windows suffered "glare" from their door mirrors as a result of the photo cell seeing less light from the rear?

[HPsauce]

Personally I've never really found glare from the door mirrors to be an issue on any car I've ever owned.
(and none have ever dimmed, just the interior one as on both my current cars)

[IT]

Rear window tints will affect the accuracy of the auto dip mirror.

In the owners handbook, Audi even say that using the factory rear blind will affect the auto dip mirrors (where fitted)...