Appendix “H”: illuminating the open bulb positions in the rear center reflector

Appendix “H”:

This posting is to describe how to illuminate the open bulb positions in the center reflector on a 993 for stop and marker lamp illumination.

I am not an engineer, mechanic, electrician or technical writer so use these instructions at your own risk. Also read all the instructions before starting.

Purchase 2 Dorman “84809 Double contact socket – Import”. These are stocked at my local Pep Boys.

See 2/11/2021 UPDATE at the bottom of this page for an exact fit socket and pigtail option.

Modify the Dorman 84809 socket:
1) When you trial fit the socket into the back of the panel you will see that a plastic part on the socket obstructs the socket from fitting in. Cut off the obstruction with a mat knife.
2) By trial fit, trim the smaller bayonet pin on each side so it clears the matching notch sides in the lens housing.
3) By trial and error trim the top of both bayonet pins (sides closest to the face of the socket) so they clears the bayonet notches on the lens housing just enough so when the socket is fully inserted it can be turned and locked in.

Identifying socket connections:
4) Install a two filament bulb identical to the existing stop/marker bulb in the corner lamp housings into one of the sockets. With a volt-ohm meter measure the ohm values between each and all combinations of the socket pigtail wires. Do this for both sockets because the color code of the wires can not be relied upon.
5) For each socket, the wire not used when the highest numeric Ohm value is measured is the Common wire (ground) connection for both filaments.
6) The wire with the lowest ohm value, when used in combination with the Common wire, is connected to the bright or stoplight filament on the bulb
7) The remaining wire when used in combination with the Common wire illuminates the lower brightness marker lamp filament.
Making the connections:
8) Tap into the wires leading to one of the existing stop/marker lamps. The wire on my car for the driver side stop/marker lamp had a red stripe and the marker lamp wire had a very light (not white) grey stripe.
9) Run a length of wire from each of these tap-in points to the same lamp (stop & marker) positions on both of the new lamp sockets.
10) Attach the common wire from both sockets to the brown ground wire already present in the center reflector.
11) Test the turn and stop lights from the driver controls.
12) Solder all connections and insulate them. Tie down and clean up the wiring layout as appropriate. Due to the proximity to the engine and exhaust system, the rear lamps are exposed to extreme temperature cycling and vibration also the center lamp housing is not sealed from external moisture. For these reasons, it is important to solder any wire connections added above vs using crimp terminals to ensure the durability of the lamp upgrade.


Install notes:

Although the entire lamp housing is vented, the newly added Dorman 84809 lamp sockets are not shielded from water or vapor to the extent the original ones were. For this reason, it may be advisable to wrap the socket in electrical tape that extends partway up the connection wires to provide some added shielding before reassembly.  I use 3M types 33  or 88 as the adhesive on the seems to hold up better over time in the environment behind the center reflector.

Also, consider adding a strobe effect center high-mounted stop light for additional safety.

2/11/2021 UPDATE:

Dorman now offers a socket nearly identical to the discontinued VW socket part number 701953123A original to the 993. It appears to only differ in the slightly different shape of the pigtail wire socket

The Dorman part number is 645-562. The pigtail wire that fits this socket can be found by doing an internet search on "tail light pigtail VW Beetle" as it is offered as an aftermarket part as well.