captcashew

All-

Been a while since I posted, but it's been a busy past year. The issues I've been having on my 1987 928 S4 automatic is probably from lack of use, but not much I could do on that. Family issues, flooded basement, etc. has made it so I've only been able to drive it a few times in the last year. Sad, I know.

Anyway, last week when I had it out, I noticed the side windows didn't seem to work very well. Would go sometimes. Then nothing. Very intermittent. Yesterday and today, pretty much won't work. The rear wiper and sun roof work 100% of the time.

Also, last week I noticed the speedometer would sometimes have a half second lag when I started. Then yesterday and today, nothing. Odometer and trip aren't moving either. I had pulled the main pod when I adjusted the fuel gauge needle and added new reflectors for the instruments almost 3 years ago. No problems then and everything had been fine since. So, I'm not afraid to do it again, I'd just rather avoid it if I don't have to.

I thought if anyone had any input or ideas. Do you think it's just coincidence that what appears to be two electrical issues are happening at the same time? Or are they related? I've heard several times I should go around and clean the grounds around the car or strange issues can pop up. I've always meant to, but not gotten around to it. Otherwise I assume it might just be corroded connections and I'll have to pull things apart, but I was hoping to do that as a last option.

If it is the grounds, does anyone know where there is a good guide to where they are all located and how to get to them?

Thanks in advance

-Bill

syoo8

The speedometer having a half second lag- meaning, it reads "zero" when you are moving, then suddenly jumps to 20mph- is this what you are referring to? This happens when the speedometer gears are slightly dirty from dried grease. It has happened to me on both of my 928s.

The side windows on my cars have been intermittent in the past, and in both cars, it was a bad connection in the plugs (they are plastic and yellow.) I cleaned these connections and I was good to go.

When you say they don't work very well, are they intermittent, or intermittent and slow?

captcashew

Sorry, for the speedo, yes, it would start at zero then I'd accelerate and a second later it would jump to 20 or so. Just did this a day or two, now nothing no matter what I do. What can you do to clean the speedo gears? I assume you have to break out the instrument pod. Would this also impact the odometer and trip meter though?

The side windows I mean they just don't work. But it almost sounds like the motor is trying to work in the door though. Very strange. Same behavior on both sides. When you say on the plugs, I assume inside, at the switch in the center console?

It's hard to say if the windows are slow when it does work though. When it does, it seems to be at the same speed it was before. Not super fast, but pretty much what I always remember them being.

I did some looking about cleaning the grounds and even the fuses and relays on the circuit board. I think that would work well too. Not sure if that is the issue or not, but wouldn't hurt. The problem is I have a couple dozen "wouldn't hurt" projects to work on.

-Bill

syoo8

In this case, I am 99% sure it is a mechanical issue, insofar as something (hardened grease) is impeding the travel of the speedometer needle. You have to remove the instrument panel. I cleaned the gears with alcohol and a Q-tip, then sprayed the gear (gently) with a very thin coating of white lithium grease- but I don't know if this is the optimum solution.

When the window is inoperable, and when you flip a switch in the side window, does the voltmeter twitch?