www.jec.org.uk

my chromatic rear view mirror was playing up,

it wasnt going blue when being dazzled from behind, and upon close inspection the chromatic section was going patchy in some areas, i have had a replacement mirror for some time now, so i got round to replacing it.

first of all i had to drop and move out of the way the overhead switch panel with the glasses case mounted in it, this is as easy as using a 2p coin to twist out the fixing and gently lowering out of the way , i also disconnected the multi-plug to make life easier,

you can now see the cable going to the mirror, unplug this cable from its connector,

the replacement mirror was firstly plugged in to check that it worked correctly , this is easy to do, just turn on the cars lights, and put your finger over the sensor on the back of the mirror , it should then turn blue , the mirror works by measuring the light in front and from behind and turning the mirror blue if the light from behind ( the car )is greater than from the front ( no need for dark garages etc to test )

you then need to remove the trim cover from the back of the old mirror stalk, this is the part that looks towards the glass, with that removed you can see the clip that needs to be pushed towards the windscreen to make the mirror slide off the mount, but for the life of me i couldnt shift it,

i eventually resorted to getting out the hammer, not as bad as it sounds, as its a nylon hammer , while pushing the back clip in ( hard on the fingers ) i gently tapped the top of the mount body downwards, that was what was required , and the mirror slid of the mount on the glass

be very careful, as any harsh treatment could break your windscreen,so on your head be it........


then fit the new mirror ensuring the mounting clip keeps the mirror nice and still on the screen, mine didnt , as someone mush have yanked it from the donor car, so i simply swapped over the spring clip from my now removed mirror, perfect fit and nice and tight to the screen once fitted

put everything else back together, and your new mirror is fitted and working

BB

BB,

Good post. I'm glad you're becoming as practical on XJ8s as you are on XJSs!

Just a thought, have you any idea how the auto-headlight sensitivity switch on the back of the mirror works? Is it some kind of rheostat? I've tried adjusting mine to the minimum but the lights are still coming on too early in the evening.

I have a real thing about people driving around in perfectly acceptable visibility with their lights on. I even read somewhere that someone is trying to re-propose the statutory bill on mandatory daytime ruuning lights, despite the fact it was thrown out last time on the basis that hundreds of motorcyclists would be killed if all cars had daytime lights. As a biker, I feel really strongly about cars with lights on when it's not necessary. Volvo have a lot to answer for!!!!!

Anyway, that's my little rant for today. Any ideas on how to lower the sensitivity?

Tks

Paul

Paul i also have the same trouble with no response from the supposed dimmer switch..........i await with bated breath for any answer that works as i have to turn off my automatic lights to avoid them being on most of the day........a common fault it would seem....Joe

Paul,

As you are probably aware the owner's handbook says one thing that may make the sensor too touchy is a dirty windscreen. Also it may be worth cleaning the sensor - the one facing the windscreen - carefully with a cotton bud to remove any dust, etc.

The mirrors maybe a bit variable it seems: when I first got my car some 6 years ago I complained about this over-sensitivity problem to the main dealer, and they supposedly replaced the mirror under warranty, but it did not make much difference. About 2 years ago the liquid crystal mirror failed completely and I managed to get a new one free fom the makers, Magna Donnelly in the USA. This replacement one has a good range of adjustment in my opinion.

I've still got the old mirror, and as I am an electronics engineer it won't hurt to try and take it apart and have a look at the circuit. I will try and see if there is a simple fix that can be done to change the sensitivity range for other owners.

Sorry folks....I spoke too soon. I spent a very wet afternoon following up my earlier idea to alter the circuit:

To get to the circuit board inside I thought that the mirror casing would just unclip along the join line between the front and back plastic mouldings. I was expecting some moulded plastic spring clips or similar, but attempts to carefully spring it apart just resulted in chewed up plastic. Unfortunately the two halves of the casing are actually glued together.

Since my mirror was already knackered I was determined to get inside to see what was there, so I cut round the join with a Dremel (mini-grinder). The circuit board is quite simple - individual components, rather than the custom control chip that I was half expecting. However, as the only way to get at at the circuit board wrecks the appearance of the mirror it's probably not worth pursuing any further.