rexpontius

Hi all

Took my 86.5 out for a drive today, which was great.
Except for the fact that I noticed the drivers-side power windows would not go down anymore.
Right side and sunroof still worked (I believe the relay switches both windows and sunroof)
Parked the car in the garage and right side also stopped working. Sunroof still works.

So I checked the following:
- Checked relay, and swapped with one from donor car, no change
- Checked fuse (30A) all good, 12v+ on both sides
- Removed center console panels, and plugged in switch from donor car. Nothing, on both windows
- Checked power and ground on back of switches, red has perfect 12v+ brown has good ground.
- Put 12V+ and ground from external battery and connected to green + black wires of switch (with switch disconnected off course). still nothing.

Is there any other common point between left and right AFTER the window switches? Or should I go get a lottery ticked because I am apparently so lucky to have the wiring in both doors fail on the same day...

thanks!

Michel

Mrmerlin

put deoxit 100 on all of the fuse holders in the CE panel and also the relay sockets,
spray into each window switch.
examine the back side of each switch to see if they might have melted the pins,
and then the pin pushed out the back of the switch.

If a window wont work with power applied to it then replace the brush block
look for the blocks on Ebay

rexpontius

Thanks!

My CE panel is completely clean and I'm pretty sure there is no problem in the CE panel, since I have power coming to the switches.
Also with an external power-supply connected to window-end of the switch, still nothing happens.

So if my deductions are correct the problem is somewhere in the path after the switch to the motors.
The windows up until today always operated flawless and without any sign of the motors going out.

So I am curious if there is another common point after the switch, or if the wires go directly from the switch to the door-plug to the window motor.
Thanks!

Mrmerlin

unplug the window motor harness and see if you have continuity to the switch
D100 the CE panel if this has not been done in the last 3 years

rexpontius

OK guys, I fixed the problem :-)
And after that, I bought a lottery ticket

Measured everything up until the the window motors and measured perfect 12V+ and ground.
Also tested with a 21W bulb, no problems.

Took out the window motor (can be done pretty easily if you leave the mechanism connected with 1 bolt, then the whole assembly can swing out so you can remove the 3 bolts holding the motor to the mechanism.
Started measuring stuff, and infinity resistance across the two terminals....

Opened the motor and inspected everything. All components looked fine, except for the protection automatic fuse, infinite resistance...
So I decided to bridge it with a 20A fuse, since the fuse on the CE panel is 30A, did not want to risk frying the original wires.

Lubed everything back up, and it works like new.

Check out the other side and EXACTLY the same issue.....

I am still baffled how it is possible that both the left and right side motor failed with exactly the same issue on the same day. Literally a few hours apart...
Anyhow, very happy that everyhing works again and in the process I also fixed the inop. central locking on drivers side.

Mrmerlin

UMMM please buy 2 new brush block assemblies for the window motors Bosch makes them,
they are on E bay

rexpontius

why would I do that? There is plenty of brush material left on the blocks (drivers side little less than right)

if they fail again I have a complete 928 donor car in storage

I drive the car about 1000-1500 miles per year and I am not worried about someone pressing the switches super long to blow the new fuses.

linderpat

Hmm, I don't believe in coincidences. Enjoy it while it works, could still be something else at play, or you fixed it by digging into the CE panel.

rexpontius

I still cannot believe te coincidence but bot motors did NOT work on the bench as well.

Both failed the continuity test on the protection inside the motor.
Really strange...

verrucktaxe

that is bizarre. like having a bad electrical component, replacing it, and the new one is also bad just of bad luck.

on my 944, i did have to replace a switch once and one of the motors. i think the dealer motor was $300, got one from pelican or somewhere online, even Porsche box, new, for about $80. what you did is obviously cheaper. hope it sticks.

Ad0911

Perhaps the old grease was gummed up too much (like in my window motors, exactly the same), making the motors draw too much amps, resulting in blown fuses. Cleaning the gears and replacing the grease with new does make the motors happy and spinning like new.

Mrmerlin

The thing is is that you just replaced a heat sensitive circuit breaker that self resets with a non-resetting part that you haven’t tested it to see if it will blow,
NOTE if the lower amp fuse doesn’t blow the possibility is is that the wire could melt,
and if the wire melts it could possibly burn up your harness.
NOTE the switch contacts could also melt and destroy your switch.

That’s why I suggested replacing the brush block, because it comes with a new resettable circuit breaker that works without anybody’s participation.

Of course the other side of the coin could happen to where the fuse could blow if the switch is held down any more than a few seconds,
while you’re putting the window up / down which isn’t hard to do,
then if the fuse blows obviously then you have to open the door panel / motor back up to replace the fuse.

Link to new fuse blocks/ harness/ switch damage prevention parts

https://www.ebay.com/itm/WINDOW-MOTO...4AAOSwLVZV5aa6

rexpontius

I totally get your point. I specifically chose a 20A fuse because the CE fuse is 30A, so it is well below what the wiring to the CE panel is rated at.

So it should not result in melted wiring.

Worst case the new fuse inside the motor blows, and I have to open the door back up.
So far however zero issues :-)