LaughaC

My '77 power windows stopped working and I cannot find any bad fuses or relays. Has anyone been through something like this before?

I'm not sure, but I may have had a power surge that caused this back when my alternator went out. I say this because both of my fog light bulbs blew about the same time.

autobonrun

I don't have a wiring diagram for a 77, but for the SC the power for both windows is common from fuse 21.

If you have a voltmeter, you should confirm that you have voltage to pin 30 and pin 86 on the power window relay. These points are directly off the ignition switch when it is on. If you don't have 12v at both those points then I'd check the ignition switch.

If you do have 12v at both those points, start verifying you have 12v at Fuse 21. If you don't have a voltmeter, you should be able to cut your ignition switch on then push the power window relay in and out and feel it clicking.

993mike

check your switches. I had bad switches and caused the power window to die.

LaughaC

The windows stopped working soon after replacing the passenger switch. I've ordered another one and will tackle it again.

A Porsche mechanic told me the motors are still good because the lights don't dim when I press a window switch with ignition on but engine not started. We also tested that power is going to each switch. A switch must be bad or a wire loosened.

glenncof

My '85 has power to windows after shut off ignition. Maybe you grounded 12V and blew the fuse while replacing sw and that took out both windows.

steve911

Check the fuse as well. My windows quit several years ago for no apparent reason. I checked the fuse, which looked fine, no joy. Replaced it with another - workng windows.

glenncof

The fuse block on my '85 was not state-of-the-art in 1985 so...

The fuses sometines go intermittent and you can clean them with sandpaper on a flat surface. Hold at angle and sand/rotate. Then go to fuse block and sand the contacts.

LaughaC

The door panels are now off, and I have power to the switches, which are also now new.

The motors may be seized from a power surge problem I had around the time the problem happened. This theory is further supported by the fact that the windows didn't both quit working the same day. One worked about a week longer than the other.

At this point I'm wondering:
1. How to switch to manual crank windows
2. If the visible gear on each side can be used to manually open and close the windows so that I can go to the track while I'm searching for a fix for the problem.

Edgy01

Start with the easy stuff,--fuses, then relays, switches, finally motors.

LaughaC

Thanks. The Fuses and Relays are fine, and power is getting to the switches.

wwest

It's probably better to also "bend" the fuse holders toward the fuse end in order to restore their "springiness" in holding solid contact with the fuses.

Last spring/summer we didn't drive our 78 Targa very muc but when we did the engine would intermittently just stop running. Turn the key completely off and then restart and everything would be fine until...

In the middle of the summer I bought a new battery for the 78 and just as a test installed the old 78 battery in my 2001 C4...no problems.

About a week ago I cranked up the 78 after 8 months storage and the engine stopped 7 times in less than 3 miles. The fuel pump fuse was good and well seated/contacted (been there, done that) and I removed and reseated the fuel pump relay. After that latter effort the engine seemed to run just fine, continuous.

Then I inadvertently discovered that the horn didn't work.

Swapped fuel pump and horn relays and now both worked....

Hmmm...

Pulled all three relay and "spread", opened (increased their springiness) the pin contacts using a razor blade. Everything seems now to be working fine.

wwest

"..lights don't dim...."

What that really means is that there is NO current flowing to the motors.

If power were flowing to the motors and the window not moving the lights would definitely dim.

LaughaC

Sounds like good advice even though the switch wires are hot. I'll go through the fuses and relays and clean the connections tomorrow.

LaughaC

bump... I need help. The new motors are only $90 each. Has anyone replaced these before?

jdogporsche

Wow...I am going through the exact same thing with my 77 Targa. I was going to take the door panel off tonight in fact. I have power on my driver's side, although the window does not move. The passenger side appears to be completely dead. Please be sure and keep posting Chris...I will post my findings as well.