I was in a junkyard a few months ago and I was able to grab a rearview mirror w/map lights and a digital compass(not the green tint type). It has some kind of reset/calibration button on the stalk(part that hooks onto the windshield). I grabbed it from a Caprice. No matter what I try to calibrate it by squeezing the button and holding it in-it won't calibrate! was there something else I should've grabbed from the car? I just grabbed the mirror w/some wiring.
Thanks for any help>

 

if you're talking about the mirror i'm thinking of, it's got a grey background around the compass and black lettering for the compass. pushbutton is located on assembly that mounts to windshield. the mirror is not the autodimming type, have to manually adjust to reduce headlight glare.

are a couple variants of this mirror. some have two wires (switched ignition & ground). some have four wires (switched ignition, ground, constant hot, ground with door open).

To Reset the Compass:
1. Drive to an open level area where you can stay at least 20 feet(6 meters)from other vehicles and 100 feet(30 meters) from structures such as metal buildings or bridges. You will need a place where you can turn the car around 180 degrees and where you can face it north. Leave the engine running.

2. Push and hold the calibration button on the rearview mirror holding bracket.It's on the drivers side.

3. The display will go blank.In about 3 seconds CAL will appear. Continue to hold the button until [a funny looking box...I can't reproduce the symbol with type] appears,then release it. The display will begin to blink.

4. After one or two minutes the display will change to 2 funny looking boxes. Now turn your vehicle in the opposite direction(180 degrees). You will need to complete this turn within two minutes or begin the adjustment procedure again."

Just a note, the next instruction is to point it north so pointing it south now should be proper. I started the whole procedure with it pointing north so I could do the 180's.

5. "Push and hold the calibration button until the display begins to blink, then release it. After one or two minutes N\cal[another funny looking display with N looking like a classic North symbol with cal in small letters at the northern point] will appear,blinking slowly.

6. Point the vehicle north. You have two minutes to complete this step.

7. Push and hold the button until the display stops blinking and CAL dissappears, then release it. The compass is now properly set and it should operate properly. If it doesn't, move to a different location and reset it again.

 

Great! Thanks for the helpful info.

 

I just have to add to stay away from areas with heavy power lines while you're calibrating.