The Electrical Haunting Continues- Starting to dislike owning my 928
09-17-2018, 08:31 PM
#1
Instructor
Thread Starter
The Electrical Haunting Continues- Starting to dislike owning my 928
I've posted this before, I've had mechanics try to troubleshoot it and I can't find anybody in my city to resolve it and it makes my car practically undriveable in Florida. Fix this and I'm ready to sell it. I've had enough...this may seem minor in the big picture but my car is now a source of aggravation and not fun anymore. This is my tipping point
ISSUE IN SEQUENCE:
1) Passenger Window- unpredictably rolls DOWN on its own- and stays down. That's right- in the middle of driving, without any switch touched- it spontaneously rolls down- a few inches at a time until completely down. Today it happened even with the Passenger window switch UNPLUGGED.
2) Next the Driver Window loses functrion as well as sunroof
3) Loud chatter from the relays in the window control module that persist until the car is turned off. Today this happened to me while it was raining- luckily I found a gas station to dart into for cover. Things didn't get too wet.
4) Unhooking the battery for 20-30 minutes generally "re-sets" everything and all function returns. Only to repeat the cycle... unpredictably.
5) I have also noted on checking that Fuse 18 (window mortors) gets quite warm but does not blow
WHAT's BEEN DONE
*All window switches replaced, all wiring traced to window motors and checked for shorts as well as sunroof motor, door switches replaced. All car groundpoints cleaned, wires from wiring harness to window control module traced and inspected for shorts, New Window Control Module installed, fuses replaced, battery terminals cleaned and tightened, and probably some other things I can't recall. STILL this completely weird problem persists and I am at the end of my rope.
Thanks in advance
1991 S4, Auto, 117K mi, 2nd Owner x 15 years, 928 Owner x 25 years
ISSUE IN SEQUENCE:
1) Passenger Window- unpredictably rolls DOWN on its own- and stays down. That's right- in the middle of driving, without any switch touched- it spontaneously rolls down- a few inches at a time until completely down. Today it happened even with the Passenger window switch UNPLUGGED.
2) Next the Driver Window loses functrion as well as sunroof
3) Loud chatter from the relays in the window control module that persist until the car is turned off. Today this happened to me while it was raining- luckily I found a gas station to dart into for cover. Things didn't get too wet.
4) Unhooking the battery for 20-30 minutes generally "re-sets" everything and all function returns. Only to repeat the cycle... unpredictably.
5) I have also noted on checking that Fuse 18 (window mortors) gets quite warm but does not blow
WHAT's BEEN DONE
*All window switches replaced, all wiring traced to window motors and checked for shorts as well as sunroof motor, door switches replaced. All car groundpoints cleaned, wires from wiring harness to window control module traced and inspected for shorts, New Window Control Module installed, fuses replaced, battery terminals cleaned and tightened, and probably some other things I can't recall. STILL this completely weird problem persists and I am at the end of my rope.
Thanks in advance
1991 S4, Auto, 117K mi, 2nd Owner x 15 years, 928 Owner x 25 years
09-17-2018, 08:49 PM
#2
Rennlist Member
Could be a flaky door lock.. as you may know you can operate windows and sunroof turning the key in the door lock when the car is parked and the ignition off. If one of your locks is worn out, falling apart inside, etc it may cause these symptoms you’re having. This is an input to the window module a lot of owners aren’t even aware of. Its a theory...needs exploration.
09-17-2018, 10:24 PM
#3
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Referring to my GTS wiring manual (sheet 3) ... window/sunroof regulator is a 25A fuse in position 18. No relays in the CEL. The regulator grounds at GP V. There are also connections to the door switches and the lock cylinders & central locking module (sheet 11).
I'd be suspicious of something flaky in the door switches or the lock cylinders since these are exposed to weather and mechanical wear. Clearly the regulator is getting some intermittent signal or ground somewhere and trying to figure out what to do with it, since a new regulator works the same way.
I'd be suspicious of something flaky in the door switches or the lock cylinders since these are exposed to weather and mechanical wear. Clearly the regulator is getting some intermittent signal or ground somewhere and trying to figure out what to do with it, since a new regulator works the same way.
09-17-2018, 11:16 PM
#4
Rennlist Member
" Passenger Window- unpredictably rolls DOWN on its own- and stays down. That's right- in the middle of driving, without any switch touched- it spontaneously rolls down- a few inches at a time until completely down. "
Oddly enough, my daughter at Porsche has a Cayman in the shop where the owners says it does the same f'in thing. She's driven it for 3 hours in the last week, hasn't done it.
Oddly enough, my daughter at Porsche has a Cayman in the shop where the owners says it does the same f'in thing. She's driven it for 3 hours in the last week, hasn't done it.
09-18-2018, 05:12 AM
#6
Rennlist Member
09-18-2018, 06:49 AM
#7
Rennlist Member
[QUOTE=The Forgotten On;15298539....Pretty advanced for the early 90s.[/QUOTE]
True, and these types of “advancements” have completely run amok in modern cars. This particular one on the 928 is, respectfully to those who have them, and, in my opinion, on the frontier of stupidity. Marketers dream up “conveniences” then engineers say “we can do that!” (With lots of sensors, switches, wiring, and circuit boards ) Then an item that is expected to get a lot of physical mechanical use (driver door lock) can eventually cause windows to open in a rainstorm, and stay open. The real irony is when the rain soaks the control unit for that system located...on the floor.
The later cars are definitely “better and improved” in a lot of important and non-trivial ways but there’s something about the raw nature of the 70s cars that I really like.
True, and these types of “advancements” have completely run amok in modern cars. This particular one on the 928 is, respectfully to those who have them, and, in my opinion, on the frontier of stupidity. Marketers dream up “conveniences” then engineers say “we can do that!” (With lots of sensors, switches, wiring, and circuit boards ) Then an item that is expected to get a lot of physical mechanical use (driver door lock) can eventually cause windows to open in a rainstorm, and stay open. The real irony is when the rain soaks the control unit for that system located...on the floor.
The later cars are definitely “better and improved” in a lot of important and non-trivial ways but there’s something about the raw nature of the 70s cars that I really like.
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09-18-2018, 07:40 AM
#8
OP: you mentioned that you have a "new" window control module. is this brand new from Porsche, or a
good used unit? also, what is the part number on the module? I have heard of strange and intermittent issues
with the later unit.
good used unit? also, what is the part number on the module? I have heard of strange and intermittent issues
with the later unit.
09-18-2018, 09:20 AM
#9
Rennlist Member
Sounds as though you need Alan's "Magic Touch"- he is the Electron Meister.
You can also check his excellent website for clues. I once had a similarly irritating problem with the locking electrics on my late S4. The problem manifested itself on the driver's door of the car. Pulled the internal door card out, could not find anything wrong, put it all back in place and dumped it with the local agents. They quickly sorted the problem, charged me for an hour's worth of labour and said there was a small problem in the passenger side door wiring. No wonder I could not find the issue.
These sort of problems go with the territory- no one is exempt - some are more fortunate than others.
Just be patient- you will get there.
You can also check his excellent website for clues. I once had a similarly irritating problem with the locking electrics on my late S4. The problem manifested itself on the driver's door of the car. Pulled the internal door card out, could not find anything wrong, put it all back in place and dumped it with the local agents. They quickly sorted the problem, charged me for an hour's worth of labour and said there was a small problem in the passenger side door wiring. No wonder I could not find the issue.
These sort of problems go with the territory- no one is exempt - some are more fortunate than others.
Just be patient- you will get there.
09-18-2018, 09:26 AM
#10
Instructor
Thread Starter
Yes- it is the new Module and I am aware of the issues and read that discussion previously and spoken to Roger about it. I could not find the original type in the US.
However, I will add that when I did go to replace the one in my car- I found it was also of the newer type (S/N) so the original owner had already replaced it. The point here being I had owned this car for many years with a "newer" module in it and never had these problems with it.
This one looked fine inside etc and I frankly replaced it out of desperation to solve the problem.
However, I will add that when I did go to replace the one in my car- I found it was also of the newer type (S/N) so the original owner had already replaced it. The point here being I had owned this car for many years with a "newer" module in it and never had these problems with it.
This one looked fine inside etc and I frankly replaced it out of desperation to solve the problem.
09-18-2018, 09:31 AM
#11
Instructor
Thread Starter
The lock as a possibility
Referring to my GTS wiring manual (sheet 3) ... window/sunroof regulator is a 25A fuse in position 18. No relays in the CEL. The regulator grounds at GP V. There are also connections to the door switches and the lock cylinders & central locking module (sheet 11).
I'd be suspicious of something flaky in the door switches or the lock cylinders since these are exposed to weather and mechanical wear. Clearly the regulator is getting some intermittent signal or ground somewhere and trying to figure out what to do with it, since a new regulator works the same way.
I'd be suspicious of something flaky in the door switches or the lock cylinders since these are exposed to weather and mechanical wear. Clearly the regulator is getting some intermittent signal or ground somewhere and trying to figure out what to do with it, since a new regulator works the same way.
Passenger lock is not original and I had it replaced (and re-keyed) probably 12 or more years ago by 928 Intnl, and never had any weird window problems....until this year
So to the present- what aspect of the lock and wiring should I focus on?
09-18-2018, 09:34 AM
#12
Instructor
Thread Starter
Getting window closed
Could be a flaky door lock.. as you may know you can operate windows and sunroof turning the key in the door lock when the car is parked and the ignition off. If one of your locks is worn out, falling apart inside, etc it may cause these symptoms you’re having. This is an input to the window module a lot of owners aren’t even aware of. Its a theory...needs exploration.
09-18-2018, 10:19 AM
#13
Rennlist Member
John - I'm guessing your mechanic is Carl Register? He's one of only two factory trained Porsche 928 guys in the Gainesville area. On anything I can't do myself, I generally take to him. The other is Larry Valero. PM me for contact info if you need it. I wish I could help. My expertise is on the OB styles which seem a bit simpler in terms of electrics. It looks like you've already done a lot of trouble shooting.
Good luck,
Chris
Good luck,
Chris
09-18-2018, 03:54 PM
#15
Instructor
Thread Starter
It may be soon
Just had a rebuilt torque tube, CV boots, brand new CSF Aluminum radiator- every coolant hose replaced, T-Belt service, AC compressor, battery, and a very long list of other work within last 10K. Amazon Green with Linen interior- no cracks/rips. 117K miles, 2nd owner, no accidents. Have all records since new.
Its a beautiful damn car and "in theory" it should be a great car for somebody.