Jaguar XJ8 X308 rear view mirror replacement

The rear view mirror used the 1997-2002 Jaguar XJ8 (X308) and related cars like the Jaguar XK8 (X100) has a light-sensitive electrochromic auto-dimming feature which is unfortunately prone to failure. The mirror develops discoloured patches. The chemical that darkens to dim the mirror tends to move around, causing blotches of brown or black. If you’re really unlucky, the glass can crack and the highly corrosive brown liquid can drip out and damage your interior. These failures seem to happen just with age, even if the mirror has never been mistreated.

The mirror houses two light sensors (front and back) to know when it should dim. These light sensors also control the automatic headlight function, and on higher/later models there is also a rain sensor that controls the automatic wiper.

The combination of these mirrors being complex and having a high failure rate means they are now scarce, and expensive.

At some point in the production run, the mirrors changed design. As far as I know, there is no way of telling the two mirrors apart externally – the only way to know is to remove the top centre console via the screw in the sunglasses holder and check the colour of the connector. Earlier ones have a 6-pin yellow connector while later ones have an 8-pin white connector.

I’ve needed a replacement mirror for ages but have been holding off due to the high price. One popped up on eBay for a low price recently, so I snapped it up. When it arrived, I realised I’d accidentally bought the white connector type when I actually need the yellow connector type.

There is a lot of confusion on forums about compatibility, whether they can be rewired, whether you can swap the glass over and leave the wires, etc. It is possible to swap the glass over, but the mirror casing is glued together and seems quite hard to open without cracking the glass (especially if you’re clumsy and impatient like me) so I ruled that out.

I was able to find the following information about the wiring of the yellow connector:

1White+12V IGN
2GreyReverse Interrupt
4YellowCell (output to exterior dimming mirrors?)
5GreenTi S (auto headlight trigger?)
Yellow connector wiring

I couldn’t find corresponding information for the white connector, but by studying where the wires went, I deduced that the blue, red and purple wires were for the rain sensor – which my car didn’t have. Eliminating those three, all the other colours matched up except the brown. Nobody online seems sure what the brown wire is for but plenty of people were claiming it didn’t do anything or was safe to ignore – so I did.

I’m not much good at electronics but I managed to solder together the 5 matching wires and insulate them with heat shrink tube. Then I carefully insulated the cut-off brown, red, blue and purple wires to prevent shorts later on, and then covered the whole lot in more heat shrink tube. For those asking why I didn’t just release the crimped connector: I tried, but it was too hard and I don’t have the right tool.

It seems to work perfectly – if I cover the light sensor with my fingers, the mirror turns blue and dim and the headlights come on. My car doesn’t have the automatic wipers so they obviously don’t work anyway. I haven’t noticed anything bad happening from not connecting the brown wire to anything.

Dimming in action

So please don’t take my advice as gospel truth, because I’m just a guy with a blog. But in my experience, if you can’t find the right type of spare mirror, you can quite easily swap the yellow and white connectors and have a functional dimming mirror again.

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