Power Window Short
 

On my 1980 911 SC the power windows have not worked since I bought it 10 days ago.
Tonight I tried a few different things.
New fuse, key to on, all three switches work and windows go up and down. I tried all three switches two times each and no problems.

Button everything up, get in car start car, passender window goes down about 3/4" and fuse blows. Tried it twice, same result. Works fine with ignition on but when I start car passenger window goes down a bit and fuse blows.

Where and what do I look for in this mystery case.

Thanks,

EDITED NOTE:
When I start the car and the passenger window goes down that is without me touching the switch.

Rob,

chances are the motors are pulling more current, because they have or are having to do more work- due to the window regulator binding.

search here on the subject, and consider using the 101 Porsche project guide to tackle cleaning the regulator. If the windows move slowwwwly, that's a major clue.

You'll have to remove the interior door cover and get inside to clean and potentially replace the regulator soft pivot that goes bad. This is next up on my own project list for my 87.

Thanks for the tip. The windows seemed to mover pretty good. Didn't seem to be binding or going slow. They both moved good when the car is off, but as soon as the car starts the passenger window tries to go down without touching the switch.

Check for bad switches. I had a switch on a '79 SC that would stick in the up position and eventually burned out the window motor.

Get those switches changed!!!

Doyle

Same thing. You can make sure the switch is centered, it might stop.

Should really get new switches.

Your problem could be either the passenger switch or the driver's side passenger switch.

Advice: Make a wiring diagram of each switch hookup with wire colors before you disconnect the
wires. Could save you HOURS of frustration. If it's too late, the Bentley will help.

if you say the ONLY difference is the car is running vs not running, it might be that your battery is a tad weak and/or when the car is running, well the engine, the voltage is a bit higher and more current available. check the fuse rating. you might try a resetable type circuit breaker if you can find one. but it might just be covering up bad switches, dirty contacts and connections or motors going bad.
make sure all connections are good and clean. clean the grounds. any resistance equals a voltage drop and more current needed to do the job. check the battery to chasis connection.

Thanks. I plan to trace all the wiring and look at everything this weekend. It's getting hot and I need to roll the windows down.

New symptom, not sure if it is related.

At lunch today I put a new fuse in and turned key to accessory mode. Pushed on switch, fuse blew. The other day it worked. Only difference is I had the radio playing today and not the other day.

However, the radio continued to work. As I said not sure it is related.

I just order one of those Short Circuit tracer tools. Should be here Monday.

short circuit tracer tools? not sure if i have seen one. i call mine a test light.:)

if you have a multi meter (MM), you set it to amps and remove the fuse and connect it up in the fuses place. run the windows up and down and check the current, then try it with the engine on. whatch to see if it spikes at a certain point. if the MM has record on it, check for a max current. try it from all the switches and see if it makes a diff.

I had the same sort of problem when I first got my 911-all kinds of window problems. Window switches have already been suggested. I am just going to add get a few from our host. The next time one breaks, you will not have to waste a couple of days of nice driving weather waiting for a window switch to arrive!

I ordered three switches but I really think it might be the drivers side switch for the passenger window, since it is the passenger window that automatically goes down when you start the car.

Thanks for the tips. I'll try the Multi meter idea.

I guarantee you it is just wired incorrectly. Remove all of the wires from the switch and figure things out.

I had the same problem with my 77 when I bought it - after the PO replaced the door panels, the windows wouldn't work and the driver's one kept blowing the fuse.

You are wasting your money buying parts at this stage. Check the wiring first.