After some tribulation, I have installed and tested the compass/map light rear view mirror from the 1992 Roadmaster in a Reatta.  Following are instructions for wiring the mirror to a Reatta.

At least on the convertible, the trim cover needs to be removed to access the wiring.

To to remove the trim cover:

1.) Unscrew the visor clips - one Phillips screw on each. Note that on the convertible, the clips stay with the trim piece, because there is a second screw on the back of the trim piece holding them on.

2.) Unscrew each of the visors - three Phillips screws on each. Gently let them drop and hang by the wire.

3.) Unscrew the black Phillips screws - one at each end of the trim piece. On the convertible, the ridge around the black top plate may get in the way of the screw. If so, loosen the end screw on the top plate a bit in order to be able to lift the plate slightly to get the needed clearance.

4.) To remove the mirror, use your trusty T-15 torx driver on the set screw holding the mirror to the button, then lift it up and off.

Convertible owners may also want to take advantage of the opportunity to replace their broken original visor clips with Kingsley's versions, (Reatta Specialty Parts), while the trim is off the car.

Reverse the above for re-installation of the trim.

Wiring the mirror:

Referring to the attached diagram, the compass rear view mirror has a 4 pin connector with the following wires [note the letter is the cavity ID stamped on the connector shell]:

A: black/white stripe; courtesy light ground (unused on Reatta)
B: black/no stripe ; main ground (must be connected)
C: black/green stripe; +12VDC for map lights
D: black/blue stripe ; +12VDC for compass

Now, the Reatta has a three pin connector with only two wires:

A: brown/white strip ; +12VDC (hot in accessory & run only)
B: black/no stripe ; ground
C: no connection

So, the following connections need to be made:

1. Black/no stripe wire on vehicle side harness to black/no stripe wire on rear view mirror harness.

2. Brown/white stripe wire on vehicle side harness to black/blue stripe AND black/green stripe on rear view mirror harness. Note that both these wires (black/green and black/blue) must be tied to the brown/white 12 volt supply for both the compass and map lights to operate.

The black/white stripe wire can remain unconnected as it is unused on the Reatta. Note that when grounded, it turns on both map lights in the rear view mirror, overriding the internal map light switches. This is for applications where the map lights double as courtesy lamps.

As far as mounting, the mirror mount is the same as the Reatta stock mirror. A single torx screw holds the mirror mount to the retainer on the windshield.

Once all the wiring is connected and tidied up, turning on the ignition to accessory or run should cause the compass display to light up with a pale blue background. The current direction should appear shortly.

I have noted that if there is a long delay before the direction appears, the mirror needs calibration. The calibration instructions follow:

1. Drive to an open level area and park vehicle. Maintain distance of at least 20 feet from other vehicles and 100 feet from buildings and other metal objects.

2. With the engine running, push and hold the push button located on the drivers side of the rear-view mirror bracket. [This is a small black flush mounted unlabeled button about 1/4" diameter in the lower extension of the mirror mount base]
The display will go blank. In about three seconds, the letters "CAL" will appear in the display. Continue to hold the button until a symbol resembling a number "8" appears then release the button. The display will begin to blink.

3. After one or two minutes, the display will change to show two symbols resembling the number "88". Now turn the vehicle in the opposite direction (180 degrees), within two minutes.

4. Push the button until the display begins to blink, then release.

5. After another minute or two, the display will change to a slowly blinking "N".

6. Now point the vehicle North, you will have two minutes to complete this step.

7. Push the button a final time, until the display stops blinking and "CAL" disappears. The compass is now set.

A couple of final notes:

The vehicle side harness in the Reatta is tucked up above the headliner. When pulled out, there is very little (about 2-3" worth) wire to work with. This makes the connections difficult, so be careful to cut the connector off as close to the shell as possible.

I managed to re-pin the harness on the rear view mirror re-using the 3 pin connector shell on the stock mirror to avoid cutting off the vehicle side connector in the car, but this is a very nasty job on this particular connector type. Chopping the vehicle side connector is probably easier, although I understand some may not like that approach.

Since the compass and map lights are both powered from the same 12 volt switched supply, the compass will operate in retained accessory power, just as the map lights will.

If there are any questions, or clarification needed, please PM me.

KDirk

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Jon