I know there are a few other peeps, along with myself, wanting to know if having your inside rearview mirror repair would restore autolamp function. This is what I found after having my mirror repaired (radar-mirror.com.)

It has been a while since I checked my autolamps so I can't be held accountable for my dismal memory. I never felt they worked properly but maybe I hadn't checked them properly. So that's where I'll start: I hooked up my factory (OEM) scanner and ran the test and it checked out 'good' (never thought to do this before the mirror was repaired.) Basically what you do is key to 'accessory'/'I', turn headlamp switch to 'Auto', block BOTH front and rear mirror sensors and headlamps should turn on. Place bright light source (flashlight, desklamp, etc. I used a small halogen desklamp parked on the front cowl and aimed a Mini-mag lite at the rear) to shine on windshield-side sensor and a flashlight aimed at interior sensor - headlamps should go off within 120 seconds (depending on brightness of lamps you're using. This spec is what is provided in the OEM scanner.) The important thing here is that both sensors are employed. If you only shine a light on the front sensor the headlamps will remain on, supposing that headlamps are oncoming and without high level rear ambient light at the rear sensor they should remain on.

With that said, adding rear ambient light will extinguish the headlamps with the adjustment knob on the rear of the mirror turned full clockwise (from driver's seat, as if looking through the mirror) in approx. 15.5 seconds and with the adjustment knob turned counter-clockwise in about 14 seconds. Now we know why they gave up on the adjustment knob... *rolls eyes*

So... now I'm not certain if my autolamps were actually inoperative before the mirror repair but they work great now, within these parameters. I'm thinking those with top-up convertibles and/or coupes with tinted windows may never realize proper function since the rear sensor also needs to 'see' quite a bit of light in order to turn off.

BTW, radar-mirror did a fine job, turn-around was one day. $99 + S&H (USPS from DFW area.)

 

These things are actually calibrated! I thought the guy who designed the autolamp sensor didn't make the grade to get on the temperature gauge design team.

For my last three Jaguars with the autoheadlamp function:

1. 2000 XJ8L headlamps wouldn't come on until it was almost night
2. 2001 XJ8 headlamps came on way too early

Both these had the rotary switch on the mirror but adjustment from one extreme to the other made no noticeable difference to the on/off point.

3. 2005 XJ8 comes on too late for my liking but there's no adjuster switch on the 4.2's

Looks like your radar-mirror repair is better than new.

Graham