Fuse block diagram

[Terry Thomann]

Pardon if this is been covered. I would like a fuse block diagram for my 1960 356B. I am having a problem with my wipers blowing fuses. I need to know what fuse it is supposed to have and where it is so I can track back the problem. Thanks for any help or advise.
Terry Thomann
Fredericksburg, VA

[Hugo Karasawa]

Check the Registry Magazine page 58. This article refers to a 356C, but I think all the 356 fuse blocks have the same arrangement. At least something to start solving your problem.
The fuse is #4 for the wipers and interior lights. It uses an 8/15 amp fuse.
https://porsche356registry-production-p ... 1483475517

[Greg Bryan]

Here you go ...

[Terry Thomann]

Thanks so much for the diagram. Funny thing. My cigar lighter and clock both work but my trouble light socket is dead. Anyone have a thought why. Thanks

[Greg Bryan]

Check for voltage at the socket - I'm not familiar with what they look like as my car doesn't have one. There should be battery voltage at the socket at all times.

[Martin Benade]

My socket appeared dead but it turned out the repainted dash had insulated the ground side.

[Terry Thomann]

What do they mean by an 8/15 amp fuse?
Terry

[Martin Benade]

I was baffled by that too but was unwilling to admit it.

[Greg Bryan]

8/15
8 amps continuous/15 amp blow

[Martin Benade]

Any idea on what happens midway between those numbers? Also do the behave the same as a modern fuse with only one number?

[Greg Bryan]

Not sure what happens in the gray area - I think the amperage can stray or spike into the 8-15 range for short periods but will blow at anything over 15 amps

[Terry Thomann]

Interesting discussion. Going to have my mechanic/electrician look it over to see why my wipers blow the fuse. Real pain in a rain storm. Bet it has something to do with the wiper motor.
Going to the Porsche boardwalk reunion in Ocean City NJ this weekend. Stop by and say hi
Terry
Red 356B Virginia plates

[Greg Bryan]

Terry - If there is too much mechanical resistance in the W/S wiper mechanism, the motor will drawing more current as it spins slower - as a motor spins faster, there is more counter (or back) electomotive force which naturally limits current. If a motor spins slower than designed, current increases because there is less CEMF. I would say that's the most likely cause.
https://en.wikipedia.org/wiki/Counter-e ... tive_force
The motor itself or its related circuitry can also have a fault that causes it to draw too much current.
You can (not easily) see if the wiper linkage is binding or sticky due to wear or lack of lubricant.

[Terry Thomann]

Thanks for the tip. I'll check it out.
Terry

[John Brooks]

Terry

if the wipers are blowing fuses, either the motor is spinning too slow due to excess drag in the mechanical side, or the brushes need to be replaced or the armature needs undercutting. (making sure the slot between the windings is clean and electrically isolated from the next one).

all are relatively easy,

1. Remove the wiper arms or fold them up, and run the motor and let the stubs spin for 5-10 minutes. Feel the motor for getting hot. Pop a fuse?? This will tell you if its the motor or an alignment in the mechanical portion. Removing the arms will reduce the drag on the motor. It also may allow the grease to soften and lube a dry spot inside the gearbox. A hot motor indicates the brushes or the armature are failing. If the fuse blows pull the motor. .

if its was hot remove the motor and pull it apart. Couple screws and a clean table to work on. Look at the carbon brush length, replace if necessary. Then look at the armature commutator where the brushes rub. There should be a thin clean gap between each contact. if not this can be cleaned and scraped until there is a small groove between each contact. They are wired in pairs on opposite sides so you can run a multi-meter in resistance across each pair for continuity.
Wipers are pretty easy, power from the switch 53 is on, they run until its off, then it will park using the power from 53a until the parking switch opens removing all power.