Mrmerlin

Since we all have the same thing in common with the 928 lots of electrical sytems are installed in our cars.
I thought is appropriate to start a thread about what kinds of strange elecrical issues we have found in our cars over time and what you did to fix them.

I have been making progress on the 88 S4 auto I have been refurbishing and have found a few odd things that I have not seen before.

Anyway the first strange thing is that my front wipers will cycle one time then park, and after about 40 seconds they will cycle again,
This with the wiper stalk in the parked position.
If I turn the delay wheel to the opposite stop then they will do the one cycle faster than 40 seconds.
Now the the other part of the story is that the rear wiper would buzz when the switch was pushed but it wouldnt cycle.
I removed the CE panel relay for the wipers and cleaned it and installed it and now the rear wiper is cycling as it should.

The multi function switch had the pin broken off as you would be facing the switch it would be the top pin on the passenger side of the steering column.
This i was able to remedy by soldering a piece of copper wire to the flat piece of brass that was left on the back of the multi function switch.

I replaced the intensive wiper switch and no change.
I still dont know why this happening, but i am getting closer to figuring it out

rjtw

This is going to be a LONG thread.... LOL!!!

OK here's mine: My car ('83) suffered from an on-again, off-again strange no-start condition where turning the key would not crank the starter not even a click... battery fine, dash lights lighting fine, other systems fine but no crank at all. I would have to wait a while and it would then start, or push start the car, and once had to get a tow. But then all would be fine for a period of days, weeks, even months before cropping up occasionally. Of course I cleaned all the usual grounds under the hood (including the famous L-jet ground), the ground strap, replaced the L-jet relay, etc. and thought I'd solved it only to have it re-occur months later. This went on for a period of several years (not a daily driver).

I finally found and cleaned a ground at the rear of the car, underneath the right hand side rear interior quarter panel. I believe this is a ground on manuals but a switch-to-ground on automatics to prevent starting except when in P or N. The car has been fine ever since, many years. The strange thing is that the ground was tight and perfectly clean. So... did I *really* fix it? Only time will tell!!!

hacksaw

When I turn on my headlights in my 84Auto the lights roll up and turn on bright. They will not switch to low beam. I have tested one of my three relays by sending it to Nate. It worked in his 84. Thanks Nate. I have jumped the relay to switch to low beam. That works. I have changed out the multi switch on the steering column. No joy. I have disassembled and reassembled one of my three multi-switches.I have sprayed deoxit into the headlight switch. Nope. I am thinking the default position of the headlight relay is high beam when not energized. If so, no signal to that side of the relay would result in high beam only. If that is the case, is the problem that the multi-switch is not signaling the hi/low relay? if not it would seem to be an open circuit between the dimmer and the relay or between the headlight switch and the multi-switch. I don't drive it at night much so not a big deal but a frustration. Thoughts?

rbrtmchl

I also believe this will be an epic thread, so thanks for starting it Stan.

The mantra of James Bailey that I have read more times than I can count is “relay – relay – relay”. While replacing relays may fix a number of problems, I believe that in some cases the relay is not the root cause of some of the electrical problems seen on our cars. I think maybe a second mantra is needed: “voltage – voltage – voltage”. I have experienced electrical gremlins when I have started my 928 after not having driven it for 2 or 3 weeks. With typical quiescent current drains, this means the battery voltage is not at the optimum level at startup. The car cranks a little slower than normal but fires right up. But then you may find something not working properly.

One example – A few years ago I started my car (’91 S4) and drove it, and after 10 or 15 minutes I noticed the temperature gauge was higher than normal. I headed home right away. The car didn’t overheat, but I could tell that things were not normal. When I got home, as I was turning off the car, I noticed that the electrical radiator fans were not running, even though the engine temperature was elevated. Besides the fans not working, the fog lights would not turn on, and the HVAC blower did not work. After some diagnosis I determined that the type-53 Ignition-X relay was not working properly. I swapped it with the horn relay, started the car and everything was back to normal. When I bench tested the ‘failed’ ignition-X relay with a 9-volt battery, the relay worked perfectly.

I have seen others comment in threads that our cars do not like low battery voltages. My recommendation when a gremlin is experienced is - step one - make sure that your battery is fully charged.

Of course, cleaning grounds, ensuring that all of the connections at the battery are tight, replacing an old battery ground strap with hidden corrosion, maintaining the CE panel, keeping the battery on a tender when the car will not be used for an extended period of time, etc. are all good preventive practices as well.

soontobered84

Hacksaw,
Maybe your harness wiring connection to the headlight is upside down? Some connections I have seen have 4 prongs and you could easily turn the connection 180 degrees to power the high beams when you should have low beams.
Good Luck.

soontobered84

The personal gremlin on my 89 that took me at least a year to figure out. I could not replicate the symptoms consistently.

https://rennlist.com/forums/928-foru...oing-this.html

The solution on post 15.

odurandina

i had never seen one of these before..... but i posted on the 968, and 944 forums....
i also dropped it on OT.....

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_____________________

Majestic Moose

The #1 tip I would give is to never assume that anything is correct. The majority of the cars built are 30+ years old and have had a long time for people to hack up the electrics. Get a correct fuse and relay chart (there are incorrect ones floating around for years '80-'83) and check that all fuse locations and sizes are correct. The same goes for correct relays and locations. This will be the first thing I check on a car.

drooman

I bought an 84 5 speed beater recently, it had "horrific electrical issues" that had stumped 2 previous owners... it was cheap and going to be a parts car but I like to try to get my parts cars running and driving so I have a realistic view of engine clutch and transmission condition before pulling it all apart. The electrical system was indeed "possessed" It had strange and various operation of many systems ...starting, lighting, wipers, windows, etc, plus cross contamination at times (turn on the key, the washer pump would empty the contents of the tank... sometimes) To simplify (or complicate) diagnosis the car had NO aftermarket wiring "fixes"...the system was unusually "virgin" After some screwing around i determined random low voltage... I tried a known good battery (instead of the old one with a 30 amp charger) No luck. Then went after battery connections.. they looked good but cleaned them anyway .. Both on the battery and the main ground connection at the other end of the strap. ... Same ****. On to the connections at the starter, then into the main connections into the relay panel.. no joy. Finally in a not so confident moment I decided to try another battery ground cable.. a "very non 928" rig from my garage. hit the key, car started, everything worked right.... took my test drive.

I sliced the sheathing off the OE ground cable expecting to find it super crusty.. it had HUGE resistance. The darkness near the ends of the cable is probably the culprit but there are THOUSANDS of these cables that are driving around and look like this, or worse, and still function. This one experienced catastrophic resistance without an obvious visual indicator.

Hymodyne

Lili's headlights are giving me fits. I have torn down the motor, checked brushes and contacts, and cleaned the disc on my headlight control motor, covered the cleaned disc with a thin film of dielectric grease, replaced both diodes with guidance from Alan, made sure the tiny ball-bearing like ends of the three contacts were properly cleaned and making contact with the disc. Replaced the #6 Relay for the motor with a used, tested working factory original. Switch the w/bl wire to the #4 position on the connector and the headlight assembly rotates smoothly, through the up and down positions. NEW* Now with the new relay installed, when I remove the R/bl wire from the #4 position on the harness when lights are on, the lights go out.

With all wires connected to the four blade harness, from the down position, when I turn the lights on from the pod, they illuminate, but do not rotate to the up position. If I manually or electrically drive the lights up, then turn them on, they light, but do not go down, only go out when I turn them off. I have a spare working motor and another set of diodes, but how could I walk by a thread like this
James

IcemanG17

bwarren97

I had posted a thread earlier about my fog lights no longer working suddenly after just replacing a bulb. Turned out to be the left High beam fuse that was just slightly off. The control for the fog light relay goes through the left high beam and the instrument panel as well, and it took me quite a bit of studying of the wiring diagram to figure that out.

My fuel gauge seems to be fixing itself very slowly. When we bought the car, that gauge was not working at all, though the low fuel light still worked. After a few months of driving, it started flipping about after filling up the tank, and continued to do so until the tank was maybe half full. Since about a week ago I noticed it sitting relatively stable for a long time, though it still wasn't quite correct. Maybe by June it'll be perfect again without me having to remove and overhaul the cluster

jpitman2

My gremlin was a bad fuse connection (@#$%& Bullets!) burning out 2 fuel pump relays, combined with a chart showing it was #13, but was actually #22. Now have home made blade fuse adaptors fitted in the high current slots.
Fuel gauge above problem could be float movement gradually cleaning shellac off the the wires? Mine never goes right to the top, but apart from that is pretty good.
jp 83 Euro S AT 57k

docmirror

Di-electric grease is an insulator. Remove it, and clean with De-Ox-It, and leave it bare. Only use di-electric in a location which is not supposed to conduct.

Mrmerlin

Well it was a balmy 31 degrees here today for a hi,
with brilliant sunshine so I went to the work on the car 88 S4 Auto.
I swapped out the wiper relay and the wipers still cycled,
so I got my spare multifunction switch and was about to swap it in,
when after careful scrutiny I found the wire I had soldered to the broken pin on the back of the switch was infact slightly bent ,
this caused the base of the pin to slide over to the next pin and just touch,
this was the reason the wipers were cycling.


I took off the connector and turned the pin 180 degrees and all is well.
I also swapped in a new dash lamp potentiometer the lights are brighter.
I got the horn working,
and the tightened the MOMO steering wheel
progress