test a power window switch
 

My window fuse started blowing and I read a bunch of threads. Lots of times it turns out to be the window switch itself.

FWIW I turned the key on and the passenger window started going slowly down then stopped and no windows worked - blown fuse. When I turn the key on but not start the multi meter pegs on DCV when across the fuse terminals.

After market switches are $20 and Porsche switches are $42. Rather than drop $ on three new switches I thought I would try to test them.

I am not too strong on the electrical stuff but I have a multi meter.

Can anybody walk me through it? or point to a thread.

I have the switches removed.

Thanks

Hi Erik,
I would seriously consider replacing all three switches. You have them out, they are each 30 years old. As an alternative, you could try interchanging switches and see if the problem moves with the switch or stays with the window.
Good luck,
Dave

I think this is a good opportunity to learn some electrical basics.

To test a switch, you need to set your MM to continuity test.
You sort of need 3 hands to do this, but you connect the black and red prongs to the prongs of the switch. When you engage the switch, there should be continuity (beep if your MM is audible)
https://www.youtube.com/watch?v=lB-aULIjiog

Your post is not clear. Are the windows moving at all when you press the switch?
If the motor is not spinning correctly, that can increase the amperage and blow the fuse.
So, it might be the motors, as well.

Right, they were working fine, then yesterday I hopped in the car and turned the key to the acc position and the passenger window started moving slowly on its own. Then it stopped and the fuse was gone. I went through another couple of fuses before I realized it was either a wiring short, bad switch, or bad motor. I thought I would start with the switches since they seem to be a common problem according to other threads.

I will mess around with the continuity thing but there are so many plugs on the back of the switches I was hoping some one would know which terminal to test etc.

If the windows were moving on their own, it sounds like the switch is faulty.
Normally, the switch should be open, and there should be no power going to the window at all.

Also, can you take the motor out, or at least access its power prongs?
You could attach two test leads attached to the battery to directly power the window motors.
If they spin at full power, which means it's not the motor. Otherwise, maybe its a bad motor.

OK Erik,
It sounds like it's only on the passenger side. Connect your driver side switch to the passenger side wires. Or vice versa, connect the passenger side switch to your driver's side window wires. If the fault moves with the switch, you know it's the switch, not the motor.
Dave

Had / have same problem Erik. Kept replacing fuses. Sometimes switch (always driver's) would go and I'd replace it. About 2 years ago I replaced door and so swapped out all parts. Rebuilt window motor, lube gears... all that. When rebuilding door I insulated old wires near switch as insulation was eaten up --- car is '80 with original door wiring. Problem disappeared since then... now it's back. Fuse this time is good and motor should be good so am suspecting 'cheap' switch is gone once again. Planning to test it today. Will take pics of process and post info later.

Here are the workings of each switch

http://forums.pelicanparts.com/porsche-911-technical-forum/288567-power-window-switch-schematic.html#post2648046

Nice one Rick!

Nice diagrams Rick. Looks like it should be very helpful. Also a little new shrink wrap over the female connectors on the window wires.
Great work, Rick.
Dave

Definitely a switch, the passenger window switch on the drivers side got all crunchy. When I removed both passenger side switches the drivers side window works with no issues and the voltage across the fuse is 0 with the key in the acc. position.

Now I wonder if I can figure out how to jumper the passenger window closed from the diagrams linked too above until the new switches arrive?

Erik.... took my switch out and tried it... Worked. Something obviously loose that reconnected.

http://forums.pelicanparts.com/uploa...1414370518.jpg

I wish there was a way to mold a connector to hold all those wires in position so the switch could just be plugged into one multiple pole connector like a modern car. That would certainly make replacing the switches much easier.

I know I have been dreaming about that, just a simple round plug with 5 prongs or holes that snaps in. No twisting wires and squinting trying to see the tiny little numbers on the side of the switch...arrrgh.

I read your post this AM but didn't have a moment to respond.

Glad you have ruled it down to the switches.

To raise your window while you're waiting for replacements just swap a good switch from one position to another.

What usually breaks on the switches is the plastic hinge point at the center of the "toggle" switch.

Once this is loose the switch portion pushes outward and the contacts and tiny springs inside the switch get cocked and all out of whack.

Do yourself a Huge Favor and buy only GENUINE PORSCHE replacement switches.

The aftermarket "equivalent" switches are really junk and will fail within a year or two.
Trust me! (and numerous other professionals who will tell you the same thing)

Hope you're back in business again soon.

Cooper

These switches are very easy to repair. The toggle pins do break but there are several DIY threads on how to fix by drilling a small hole where the broken pin was, then inserting a small nail or similar. Easy to do and works for years.