OK, I have been reading all I can find regarding this solar sensor on top of the dash on my X300. I know it is also on XJ40's etc.

What is it for, what does it do??.

Most of what I found to date is that it "must never be covered", dunno why, I dont have auto headlamps etc.

It is possibly something REAL simple and I just have not got it yet.

 

I *think* the climate control uses it in calculating....something.

There. Does that help? :-)

Cheers
DD

 

Thanks Doug.

Thats better than my original thinking.

I first thought it had something to do with the car waking up and going to sleep, down with dusk, up with the dawn, mmmmm, it is called a solar sensor after all, but that went out the window when I drove it at night, haha.

 

It lets you know when 'the end of the world is nigh' and will post up the message 'Sun Not Found' on the VCM, thus giving you time to leave the planet.

Forward thinking by Jaguar if you ask me. LOL

 

Actually it is the antenna for the system that causes a major breakdown of the car soon after you make any offhand comment about how well it has been running.

 

Now this is really tweaking me off. I read about that sensor somewhere but I cant remember where I read it, nor, more importantly, what it does! I am strongly thinking (a dangerous activity) it has to do with the climate control system, and also the rear view mirror dimmer. I am going to have to plow through my books etc and find out now. Thanks a lot!

 

Ford used it as an additive input to ambient temperature in their EATC (Electronic Automatic Temperature Control) ie....solar sensor output was read by the control board as additional ambient temperature, over and above the output of the ambient air sensor. Of course, how it was integrated with the ambient sensor and how much it was weighted was proprietary. Whether or not that is how Jaguar utilized it and whether the "Ford way" had worked its way into the design by the mid '90's if not would be purely a matter of conjecture on my part. Not sure whether or not the autolamps use its output or not...as I don't have that useful feature on my VDP, despite never having to turn headlamps on or off in my 03 F150 or '91 Grand Marquis...

 

I am quoting from the Jag disc.

"The solar sensor is mounted on the top of the facia between the facia defrost grilles. The sensor is constructed around a photo diode to measure direct sunlight. The sensor provides an output response signal to the A/CCM; this ensures the in car temperature stability whilst reducing outlet temperature to compensate for solar heating load. The solar sensor is fitted to air conditioned vehicles only."

There you have it. Massively over engineered, but cool.

 

Thanks guys.

Clears that up real quick.

ALL the answers are relevant in my opinion.

 

Solar sensor ? I don't think I have heard of such a thing .I think you can also deposit sun energy thanks to this sensor and when oil supplies come to end you can still run and enjoy your ride with 0 emisson lol