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Wiring of 3rd Fuse Box

  • 1971
  • 911T
125 000


Thank you for your reply on the silver Bosch coil.  I'm still wresting with electrical problems, among them Fuse Box III in the engine compartment.  The car stared life as a Sportomatic, but the previous owner pulled that transmission in favor of a 5 speed, which conversion he did not finish before selling me the car.  He also pulled all the wiring without labeling any connections; so I have stared from scratch on the rewiring hookup.  None of the electrical diagrams I have show wiring for a Sportomatic.  So, for a '71T that is now a 5 speed, what should the wiring be for Fuse Box III?  Is the lead for the rear window heater hot at all times, or does it come from the alternator?  There are two leads in from the left side of the Fuse Box, one hot at all times, and one from the alternator.  There are three leads out, (1) solid red, which should be red/black to the rear window heater relay; (2) red/white possibly to the speed switch, which may not be used on this model; and (3) blue/yellow which may go to the tach amplifier, Bosch 0227990001.  On the Fuse Box cover, Porsche says Fuse #1 is Sportomatic, #2 is "rear window wiper (dont' have), starter magneto or dashpot;" and #3 is rear window heating.  Also, what does the Wehrle relay PN 901.615.109.03 do?

Thank you for your help,


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