: MCS auto-dim rearview mirror
Feb 27th, 2012, 02:41 PM
Hi, my R53 has the auto-dimming mirror. According to the manual, this should stay dimmed all the time except wen reverse is engaged, when it should un-dim to give better rear visibility. Is this how they actally work in practice? My car has a totally blacked out rear windscreen - zero visibility when looking in from outside, and extremely low visibility when looking out from inside. No idea what the original owner was thining of when he specc'ed that, I'm pretty sure it must be illegal ... but anyway, I see no change in the mirror (or visibility through rear windscreen) whether reverse is engaged or not.
I've cleaned up the photocells (front & back) which made no difference, and've checked that there are no obstructions on the front windscreen itself. I guess from that the the mirror electronics have failed internally (either not getting charge from the photocells or failing to detect reverse being engaged).
As my visibility when reversing needs all the help it can get on account of the tinted windows, I'm trying to understand whether the mirror has failed in the dimmed or undimmed state. If the former I may try to get it fixed; if the latter I'll leave it as is. Any ideas?
Feb 27th, 2012, 03:02 PM
I thought it was supposed to be "undimmed" all the time, then dimmed when someone came up behind you with their lights on (possibly just in low light, too)?
That's what my old R53 did anyway! When reversing, say, on to a driveway with floodlighting, the mirror would dim (as though you were being dazzled by another driver's headlights) regardless of what gear you were in... I certainly never noticed a difference when popping it in/out of reverse? Maybe it is/was just really subtle? I know people have reported that the effect is more subtle with the factory rear tints, which mine had.
I suspect that yours probably isn't working at all because of the really, really dark tints? :)
Feb 27th, 2012, 03:18 PM
oh - the handbook says
"Interior mirror, automatic dimming*
This mirror dims automatically as required. The mirror becomes clear again when you engage reverse gear or select position R on the selector lever."
I just tried shining a torch into the mirror (from within the cabin) and it didn't seem to dim at all. However I also twisted it round and used it to look out of the (mildly tinted) drivers side window and the visibility was pretty normal (i.e. not like I'd expect if the dimming feature was permanently operating due to a malfunction). I'm still a bit confused - don't think it seems to be correctly sensing light that should trigger it dimming - however if it's not failed "dimmed" then it's a moot point for me as the opaque rear windscreen pretty much makes dazzling headlights a non-issue anyway.
Thanks for the feedback.
EDIT - I guess I should repeat the torch test at night so that the ambient daylight isn't an issue. That would at least prove whether the mirror is working or not regardless of the tinted windows!
Feb 27th, 2012, 03:32 PM
No idea what the original owner was thining of when he specc'ed that, I'm pretty sure it must be illegal ...
actually, I just did a spot of googling and according to direct.gov "The rules on tinted windows don’t apply to the rear windscreen or the rear passenger windows.". So, not illegal, just stupid :rolleyes:
EDIT - thanks mods for moving my thread to correct location - sorry, I'm still getting used to all this :-)
Feb 28th, 2012, 10:45 PM
the dark windows are probably covered with after market tinted film you can remove it.
if an auto dimming mirror was diy retro fitted then the reverse override would not work, as there are a live and earth available but the reverse wire would have to be put in which most people wouldn't bother doing.
Feb 28th, 2012, 11:05 PM
good point - will have a look to see whether I can peel off the tint if it's just a stick-on job. I now suspect that the mirror is a factory fit and it's just not dimming at all due to the tinted windows cutting down headlight glare to a point where its insufficient (at the mirror photocell) to ever trigger the dimmer.
Jul 17th, 2012, 02:12 PM
dimming mirrors usually check the light levels forwards and backwards. This way if it is bright out the back and bright out the front it knows it's day time and won't dip the mirror. If it's dark forwards and brighter backwards then it thinks it's night time and dips the mirror. Check to see if the forward sensor is covered. If it is a retro fit then the windscreen may not have the required aperture to allow light in and it will think it is always night time and there fore dip the mirror with any level of light coming from behind. Do you also have auto lights and wipers? I believe they were all part of a package.
Jul 17th, 2012, 08:22 PM
The rules on tinted windows donít apply to the rear windscreen or the rear passenger windows.". So, not illegal, just stupid :rolleyes:
If you think about it, its no different to driving a van where that has solid metal panels at the rear sides and back doors, you cant see through that either. :hmph: