I have owned my 1968 911T targa (European) for more than 38 years, and have tried to keep everything not only functioning, but also looking "factory original". I recently noticed that my turn signal high beam flasher was NOT working, much to my chagrin. After checking wiring and fuses, I concluded that the turn signal switch was malfunctioning.
My first step was to see if I could locate a replacement switch: just in case I could not clean or repair my existing switch. Needless to say, the switch is NLA from Porsche! I was very fortunate to track down a used switch from Carquip: but these are extremely rare, and as it turns out, there are subtle variations at each vintage year for the early 911s!
Porsche used a variety of turn signal switch configurations in the early series 911s. From the Early 911 PET Catalog (published in 1969), the following switches are detailed:
Porsche Part number
(1965 - ) 1967
911 /S 912
911 /L 912
911 /S/T 912
In 1968, in addition to new Emission Control requirements, the DOT required interior knobs to be soft and protected: so the turn signal switch of the 1968 USA imports and the 1969 cars had modified signal handles with removable rubber end tips.
The "Combo Switch" is a multi-function switch providing left- and right- turn signal as well as low-beam, high-beam and headlight flasher functions. The left- and right- turn signal contacts are sliders covered beneath the top plate of the switch; and the return-mechanism pins are visible above this top plate. These pins are pushed by the cancelling ring of the steering wheel to complete the turn signal when the wheel turns back through neutral. The headlamp low-beam, high-beam, and flasher contact points are visible in the interior of the switch from above or below, and are activated by pushing the lever forward (high beam); neutral (low beam); or pulling the lever back (flasher).
The headlamp switch portion is made up of four layers: the top layer (yellow wire) connects to the Low Beam; the second layer (white and gray wire) connects to the switched power from the dashboard Light Switch; the third layer (white wire) connects to the High Beam; and the bottom layer (red wire) connects to the always-on power from the dashboard Starter Switch.
The first step is to remove the steering wheel and switch housing shells from the steering column. This is nicely explained in the first portion of the Pelican Parts Tech Article "Replacement of Steering Wheel Switches". If you disconnect the battery to avoid accidental blasting of the horn when removing the horn button, you will need to reconnect the battery for later testing of the switch.
When the lever is in the neutral position, the center contact is toggled upward against the top contact (yellow wire).
When the lever is pushed forward, the center contact is toggled downward against the lower contact (white wire).
When the lever is pulled backward to "flash": several things happen at once: the toggle block itself moves slightly downward pushed by the lever, separating the center contact away from the upper contact (no low beam); at the same time, the bottom third layer contact (white wire) is pushed down upon the fourth layer plate (red wire).
Sending power temporarily to the high beam. Releasing the lever returns the switch to neutral.
Burnish the switch contact points. Place the bath towel on the driver's floor beneath the steering wheel. Cut the 600-grit sandpaper into about 8 strips 0.25" to 0.375" wide x 9". Lying on your back on the driver's floor, look up through the exposed turn signal switch interior, and site the 3 sets of contact points. Illuminating the switch from above using a flashlight or lamp may help. Carefully feed one of the sandpaper strips up through the interior across the open pair of contact beads (center pair, high beam): like threading a needle! Then reach above the switch so that one hand is holding one end of the sandpaper, and the other hand is holding the other end. Coordinate your hand motions to move the sandpaper strip lengthwise back and forth pulling pressure to the grit-side against the bead. You should notice a streak of copper/brass forming on the paper strip: which means you have cut through the tarnish. Take another strip and thread through the same contact pair: this time with the grit against the other contact bead: and repeat the process.