Another Power Window "Issue"

[merrellbr]

Have a stock 1980 SC Targa with the power windows (PW) down and they won't go up. This has just started, been fine for several years, haven't made any recent changes to the electrical system or added anything electrical.

Symptoms:
1. PW Fuse blows every time I turn the ignition key on, even without doing anything with the WP switches.
2. Have put in several "new" PW relays with no effect, fuse continues to below when ignition is turned on. Without relay in place, the WP fuse does not blow when ignition is turned on.
3. Put all new switches in both doors, no change.
4. Couple of days ago when I shut off the car after a trip the speedo stayed at 40 mph with the ignition off. When I open the door the speedo dropped to '0". When I press the interior light switch in the door frame (either side) the speedo goes to 40 mph. When running the car on the road the speedo registers fine, steady and true.

Over-all the car runs fine, no other issues other than PW and speedo.

No idea if the two problems are related, but I am rapidly running out of the blue fuses for the WP!! I really don't want to randomly tear into the wiring and am look for any "sage" advise from a Porsche "electrician"!!??

Thanking all in advance for the help and encouragement.

Bruce

[steely]

Hi Bruce,

It could be combination of things like: an older motor, or regulator issues like dried or dirty lubrication, broken guides (like the plastic rollers), or a missing pivot on the helper spring. If the motor hasn't completely given up, you might find one of the existing threads that show you how to dismantle/clean and lube the door innards. This may go a long way to extending the motor life.

There was at least one good thread on cleaning/lubing the regulator, and several on fixing the spring pivot.http://forums.pelicanparts.com/porsche-911-technical-forum/576413-what-found-laying-bottom-targa-door.html
hth

[Porboynz]

Does the relay operate when you insert it with the ignition on and that causes the fuse to blow? Or does the fuse blow immediately you insert the relay? Either way, save yourself a bunch of fuses and wire up a spare headlight bulb in series with the fuse, or instead of the fuse if you like. (I like to still have a fuse in series, but I'm ultra cautious) That way the headlamp will light up bright to show a short to earth and you can take your time isolating the switches, the relay, the door motors etc until you find the problem without the stress or threat of burning any wiring. The headlamp bulb is a negative co-efficient resistor, lots of current when cold but as soon as it heats up the resistance increases in the filament to reduce the current, plus it gives an easy indication of a short to earth. When you remove the short, the lamp goes out, easy.

[Daviboy]

I have exactly the same issue but only with the passenger side window. I read a thread here that it may be something to do with the wiring harness which goes into the door from the tub. Anyway I have ordered a new power motor for that side (old one was on its way out anyway) and will be checking the harness when it arrives. This thread may help you http://forums.pelicanparts.com/porsche-911-technical-forum/288567-power-window-switch-schematic.html or this one http://forums.pelicanparts.com/porsche-911-technical-forum/386143-wiring-window-switches.html

[Tidybuoy]

I don't think the speedo issue is related as the PW circuit is it's own complete circuit.

I recommend pulling out the door switches (one at a time) and using some needle nose pliars, make sure the terminals are not touching and causing a ground short. This may depend on the type of switches your car uses.

My car was having PW fuse issues and it turned out to be one of the wires, at the window switch was rubbing the metal frame where they secure to the door. As soon as I bent the switch spades to be more seperated and not touching anything, the fuse issue went away.

To compound the problem, Porsche did not leave much slack in the PW wire harness so it's very easy to short out one of the wires at the switch.

Hope this helps.......Vern

[steely]

I mis-read the post and assumed that the fuse blew once you pushed the PW switches.
I see you purchased all new.
I agree it could be a short, if so, one likely place is the harness near the pass-thru between the fender and the door as Davy mentioned.
I'm not sure if the PW power goes to the plug that's visible in the fender above the hinge with the door open, if so, you could try to isolate the problem starting there.