Michael Benno

My driver's window is stuck halfway down. This was an intermittent problem that seems to have become permanent. I could use your help in the next step of troubleshooting.

Passenger window works good.

The fuse tested is good.

The switch tested good. I pulled and cleaned the contacts and removed the plastic bits to ensure good contact and added contact enhancer and tested everything with a multimeter.


Now what?
Is there a relay I am missing that could be overloading?

Do I pull the door panel and test the motor? Is it safe to hot-wire the motor with 12v?

Are the wires prone to breaking where they enter the door?

Any BTDT would be appreciated.

Mike
1988 928 S4 5spd

ltoolio

I'd expect the relay would affect both windows rather than consistently the drivers window.

I had a frayed wire on the door tube, so I suppose its possible you have the same.

You could pull the door panel off and test w/multimeter if the motor is getting power when you apply the switch. And yes...you can apply 12V to the motor.

It could be an issue with the window guide/slider causing it to stop working. Should be a easier to verify once you've got the panel (or at least the smaller panel above the arm rest) removed.

kmascotto

Its likely your electric window motor...its an easy fix.
follow the link https://rennlist.com/forums/928-foru...r-r-and-r.html

Wisconsin Joe

What does the voltmeter do when you press the switch?

If it moves (down) when you hit the switch, the motor is getting power and not turning. Motor bad or window stuck.
If it doesn't move, then there is no power getting to the motor (wiring).

As a "worth a shot" - Try opening and closing the door while the switch is pressed. If there is a wire broken, you might be able to get continuity by "wiggling" the wire.
Don't laugh (at least not too hard) it works on my 944.

WyattsRide

I had this same intermittent problem with my driver's side window. For awhile I was able to move the wire loom that goes into the door to get it to work. When that didn't work I could open the door to a certain spot and it would work. I knew it must be a break in the wire that made contact at varies times. I finally pulled the door panel and inspected the wire. Found the break easily, made the repair and it's been perfect since. My bet is broken wire on yours too.

FredR

If thee grease on the guide rail, the quadrant plate of the drive cog dries out the stiction becomes too great for the motor to overcome. Sometimes just pulling this lot out, cleaning it and re greasing will solve the problem assuming it is not a broken wire [or both]. Disengaging the motor from the lifting mechanism gives an indicator if the motor then starts to work.

The job itself looks a bit involving initially but once you get used to it I reckon on having the assembly out and back in within an hour or so.

Rgds

Fred

Michael Benno

Thanks everyone for the quick replies. I'll pull the door panel and first test connectivity from the switch to the motor. This should tell me if the wires are good.

Then I'll give the the lift and gears a good clean and lube to eliminate friction.

If that doesn't work I'll focus on the motor.

Wish me luck!

Speedtoys

Ya..the WHOLE motor and regulator comes out with 4 10mm bolts in about 3 minutes once you have the door card off.

On my kids 85, I removed it all, pulled the motor off and apart, and soaked/cleaned it all in solvent overnight.

The old grease was a petrified glue.

Mrmerlin

Wisconsin Joes suggestion on the test watching the volt meter is a good guide on how to proceed and what to fix.

Beyond that dont forget that adding some deoxit 100 spray to the switch may restore function.

NOTE that the switch contacts can melt if the contacts inside the switch are dirty,
or the window motor is slow due to a sticky arm pivot or congealed grease in the motor.

The fix for this is to look at the back of the switch and see if any of the contact pins look to be pushed out further than the rest,
if so then use a soldering iron to heat the pin and push it back into formation,
then consider using some JB weld to pot the rear of the switch to hold things in position.

Also note that the edges of the toggle portion of the switches may hit on the switch mounting area and thus not be able to be fully pressed,
this is usually a clue that the contacts have melted.

NOTE also lubricate the arm pivot this is easy with the window down and the some spray lube and a red straw and a flashlight simply find the arm pivot and then drip the oil onto the pivot a few cycles should have the arm moving freely

MainePorsche

See this too after you check your motor/gear function. It is for the window switches.

http://members.rennlist.com/v1uhoh/windowSW.htm

Michael Benno

I removed the door panel and tested the wires connecting the motor to the switch. Both up and down connections tested good.

Thanks tips above, I removed the regulator and checked the movement. It was clean and smooth.

I pulled the motor apart and noticed some odd wear on the barrel but noting that would stop the motor from turning. But then I noticed the culprit was one of the brushes was sticking in the fully recessed position. I tried everything to get it to operate smoothly but it kept getting stuck. I even removed the spring and cleaned and smoothed the pocket for the brush but I could not figure out how to prevent it from sticking. Bugger.

I could see how the sticking brush would have caused the poor wear marks as well and loosing contact as the opposing brush wore down.

Looks like I found my problem and looks like I'll be heading to the salvage yard again, unless someone has a good source.

Speedtoys

Yup, just reverse the wires to the motor to go either way. Purty simple.

Mr Earbrass

I am sure that you all know this, but similar vintage Saab 900's use the same window motor and are typically a much cheaper replacement then the same part from a used Porsche.

Michael Benno

No I wasn't aware, that is a very good tip. Can you give me some part numbers or models to look for, or better yet a new parts supplier.

Petza914

Volvo motors too, I think.