power window headlight circuit cross

[tclyder]

My son has a 1985 early 944 and when the headlights are on (The car is running) the power windows will not work.

When the Headlights are off (and retracted) the windows work but are slow.

I noticed by accident that when he was trying the windows (the lights were off) that when he pressed the switch to lower the windows the lights light up dimmly (but then do not open).

This tells me there is a short between the two circuits.

Does anyone have any idea how I could toubleshoot this problem

Is this a ground problem?

Thanks

[SoCal Driver]

He has the early 85? The one with the square face instrument cluster?

Don't see any way that there can be a "short" between these two circuits. I think you have a low votage problem.

Most likely all of the cables to the battery and the grounds to the chassis and engine block need some serious cleaning.

Could also be worn brushes in the alternator. Check for about 14 volts dc at the battery with the headlights on and at a about 1900 rpm.

The regulator (and thus the brushes) is replaceable for about $20 in parts and an hours labor (yours). Get the adjustable one. Set the charging voltage at about 14.4 VDC at the battery.

Also the connections on the window motors could be corroded. This requires that the door panel be removed and these contacts cleaned. Worked wonders for my slow window problem a few years ago.

You didn't say if the headlights are stock or flame throwers. Or if there is a stereo power amp.

P.S. Add the year and model to your siginture line.

[tclyder]

The car is an early 1985 944 that has 120K and is stock.

The headlights are stock.

No special amp.

I discount the low voltage becuase the lights are bright.

Also why does the lights glow (still retracted) when the power windows are activated. Some how votage that should be going to the windows is flowing into the headlight circuit.


Tom

[SoCal Driver]

Bad grounds.

Circuit feed back but not a short. Clean the grounds. The electrical diagrams on Pelican for the 944's will show you where the grounds are if they are not obvious.

Hint: there is a large ground cluster behind the fuse/relay block next to the inside of the car that the electric windows ground to.

The headlights ground on the frame just behind each unit.

Then it's also possible that you have a car the previous owner (PO) had electrical problems with. Ususally melted wires behind the fuse/relay block after trying to install a radio or electric anttenna.

[tclyder]

Hey Guys - any more ideas on my power window and headlight problem - any thoughts that it might be the fuse / relay box?

Tom

[turbohead7]

That does sound like a low voltage problem. I would first follow SoCal's instructions. Then take a real close look behind the fuse/relay panel with a light and a small technician's mirror. You are looking for burnt wires or a melted fuse block or harness. I've seen many people try to upgrade their headlights to H4's, they pull more amperage then the headlight circuit and end up destroying the fuse block/wiring. Also, Porsche usually ground side switches just about everything. So your p/w voltage isn't escaping, there just isn't a good enough ground for the windows when the lights are on. It's super easy to pop out the driver side driver window switch and check your resistance to ground with an mutimeter. Try this also when the lights are on.

[ae1969]

Definitely a low voltage problem............But if you rule out the grounds........

My second inclination is the motor on that window is going, it wants to draw more power.......but with the lights on....not enough power to get that motor going.

The motor is a bit of a pain to get out, but can easily be tested and rebuilt by any small electrical appliance shop.

Good luck.

[carsontc]

Originally posted by turbohead7
It's super easy to pop out the driver side driver window switch and check your resistance to ground with an mutimeter.

the grounds are the solid brown wires but you probably already know that by now

it is possible the PO tried to 'add' more power to his windows by adding a wire or two

look for wiring that doesn't look 'factory'

if you don't have the owner's manual, the relay & fuse panal info can be found here:

http://www.geocities.com/MotorCity/1760/earlyfusepanel.html

of course, the window relay is not with the others...it's under the dash but to the right of the steering column

the wires (color) going to the 'electric window control relay' are:

to relay coil:
term 86-black/yel
term 85-brown

to relay contacts:
term 30-red
term 87-red/blue

the +12 volts comes out this red/blue (term 87) and goes to the door switches

[tclyder]

At least now I have a game plan as to what to look for.

I will start on this early next week.

I have enclosed pic of my sons 1985 early 944. I think it is pretty cool.

It is a non-turbo but has the turbo nose on it.


I am also looking for a used pair of turbo fog/driving lights for this car.

Tom

[tclyder]

[carsontc]

very nice...it looks like a complete 'S' body upgrade...w/euro rear valance

[TCMdocs944]

Hey, that car is in great shape. Looks like about $1000+ in body upgrades.

Hmmm, that points to possible PO electrical mods, stereo etc.

These cars have notoriously poor electrical capacity for "extras" ie radio, antenna power windows.... The other posters are right-on about the grounds. In my 83 just cleaning the grounds, battery terminals and firming up the connections made it run and act like a whole new car.


Now, about those rims

[SoCal Driver]

Four additional "flame throwers" and PO wiring.

Deffinately potential problems.

Looks like a complete wire loom check to me.

[tclyder]

So whats wrong with the Rims?

[tclyder]

At times I am really dense ----- What does PO stand for?

THe old man

[carsontc]

previous owner

I thought abbreviations or a glossary wudda been in FAQs but I couldn't find it...I'll look around

btw...I like the wheels

[tclyder]

Thanks for all of the input - hope to start to troulbe shoot this next week ----- anyone else have any Ideas?

It looks like many of you have looked - I am shure some one has run across this type of problem before.

Thanks

Tom

[TCMdocs944]

please let us know about your progress, if we can be of any help.

Good Luck