electrical stuff / sunroof

[C. Clark]

I have a 69, 912 with a sun roof, the motor that runs the roof works fine when tested with 12 volts from the battery. The wiring from the switch reads 12 volts on a meter, but when the motor is hooked up to that wiring it won't run. Is there a relay in this area that could effect the motor or could I have a ground problem? Any help would be great.
Thank you,
C. Clark

[Roland Kunz]

Hello

No there isn´t a relay. Just messure if the wires from the switch to the motor will have to much resistance.

As you have the old gflat Bosch unit the motor needs two directional wires and one ground.

If you test it the put the rubberconector to the drive on it and try if you can brake it down in speed or if it will even start under load.

You can open the motor to renew the coals.

Also rebuild is posible. new units are NLA but those drives wgere used up to 1972 in every Porsche window lifter and still up to 1985 in all 911. Mercedes 108 - 111 have them also.

If your sunroof is bloked the motor normaly will start with a nocking noise and go on mechanical lock.

Grüsse

[C. Clark]

Roland,
The motor has two wires going to it one yellow and a blue, no ground. Does the motor ground itself to the body? What do you mean the wires fromn the swithc having resistance?
As I said the motor run when connect directly to the battery, reversing the wiring changes direction, I assume that is what's suppose to happen, or does that really mean anything?
If the motor is the problem, where is the best place to get another?
Thank you for your help
Charles...

[Roland Kunz]

Hello

Yes ground is via body bou there are rubberblocks so under one is a short ground wire.
Maybe I mix it up with the Ferrari/Maserati junk.
The motor will run without ground but will not have tourqe power.

First you have to messure if the switch works proper by changing the curency direction. The next thing is if the wires are not corroded and have a high resistance.
The resitance will drop the voltage and heat the wires.

Not to forget if the part isn´t mechanicaly overloaded. The best is to use a boosterpack and run the motor direct from the rear.

UPS did you checked the fuse for the sunroof circuit ?

Grüsse

[C. Clark]

Roland,
The car has been parked for several years prior to me buying it. The previous owner who has no reason to lie said the sunroof opened fine when he last used it several years ago. I suspect a bad wire, bad ground. I believe the motor and fuses are ok but just for the heck of it do you know which fuse on the fuse box controls the roof, the id label is gone from the cover. Oh yea, who has the motors for sale.
Thank you for all your help.
Charles...

[Rich G]

C. Clark,

This is just for a little additional information. I have a '76 912E w/ sunroof and just 3 weeks ago it hung up halfway while closing (fortunately at home pulling into the garage after an afternoon run w/ my wife, Susie). My buddy (mechanic) and I pulled the roof assembly out and ordered a new rubber clutch. What happened was the roof bound up in the runners and the clutch did it's job to protect the motor. It actually sheered due to age. I thought my motor was shot also, but it's actually a pretty robust unit. The clutch was only $24. from Porsche which was a nice surprise. Good luck ...

[Roland Kunz]

Hello

The 76 still has the same system and motor.

After several years nonusage the grease will get harsh and make the roof stick.

The motor will then don´t have enogh power to brake the roof loose. But you will hear the motor runing against the mechanic resistance. If you open the zipper you will see the little rubbercoupler siting direct on the motor shaft.

Pelican parts have a electric wire diagram on there homepage and the 912/911 are very similar. The sunroof had sometimes an extra small two fuses box.

Grüsse

[C. Clark]

Thanks for all the info, I have a much better grasp on what I'm dealing with.
C. Clark

[Roland Kunz]

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1965_911S.jpg

It may help a bit.

Grüsse