I recently purchased a 2004 F-150 Fx4 Supercrew. I noticed that I have a black box attached to the rear view mirrior, and there is an electrical cord leading down from the headliner to the black box. There is also a button on the top of the black box. At first, I thought it was an auto-dim rear view mirror, but my windows sticker does not list this option. Also, there are no buttons on the mirrior itself, rather, there is a manual flip controller for nighttime driving. The dealership had no idea what this is for either (nice huh?). The owners manual does not explain this either.

Pressing the button does not seem to have an affect on anything either.

Anybody have any ideas?

 

I believe the box is for the compass. Hadn't noticed a button on it.

 

Now that you mention it, what tha heck is that.... could be a compass, but why mount that up there, plenty of room inside the dash...

Probably some sort of device used to track the movement of the truck..sattelite connect so big brother can keep track of us...

 

It may be a photo sensor to automatically dim the mirror when some jerk has their high beams on behind you. My folks used to have a windstar with that feature.

 

I have the same black box and thought it could be the sensor
for the auto headlamps

 

The 'black box' is the compass. The autolamp sensor is integrated with the blinking red alarm device on the dash. Cover the latter with a glove, etc. and you'll note the loss of autolamp function.

 

I always thought it was for the auto dimming of the mirror but he says he does not have that option. If it is the compass, then what is the button for? Calibration is done, on mine at least, through the control panel.

 

i was wondering myself. after staring at it for awhile i thought it
was serving multiple purposes.
1: compass
2: thermostat
3: nighttime sensor for unlock illumination
4: mirror dimming
doesn't seem to make sense that it has only one function.
But now you've got my curiousity about the ( button ) don't
recall a button ( will now go look ) ....

' 04 f-150 xlt 4x4
reg. cab flareside
drk toreador red

 

might be a good spot to mount a radar detector, the power is already there

 

I had a Lincoln that auto dim headlights (not mirror) sensor in the postion described. It was pretty cool, you could run around with your high beams on and as soon as it sensed headlights of a car coming towards you it would auto dim. You could adust how far out it would sense the other car.

 

A compass won't work correctly if it is shielded by metal. Magnetic fields? Anybody know?

 

Grimalkin is correct. It is the compass field sensor.

Nothing more, nothing less.

 

I have a wire, comes from the headliner plugs into the black box, then goes out to the mirror, which is autosensing, maybe its a just power to the mirror, who knows?

 

does anyone read their owners manual? and the black box attatched to the mirror is the compass module. and the button is for setting variation zone on models without the message center option.