1997 528I Auto Trans Indication / Malfunction

[madjack181]

I have a 1997 528i w/ auto transmission with 183K miles on the clock. I've had the car about 6 months, changed the trans fluid & filter about 2K miles ago. At the time the pan was clean, the magnet had about 3/8 of an inch of black/grey paste on it. I've had no problems with the transmission before or after the servicing until today.
I've noticed when I select Reverse, the indicator on the instrument cluster reads "S". When I go to Drive it goes blank and then as I drive it intermittently will flash "D". When I go back to Park it reads "S1"
While this is going on the transmission is acting weird. In particular, when you come to a stop it almost acts like trying to stop with a manual trans without pushing in on the clutch. It drags the engine RPM down almost to the point of dying. When you accelerate from a stop it shutters and the shift points are all over the place.
Do I have a a transmission crapping out or do I have an electrical problem?
Recently I've suspected that my alternator is failing...if that makes a difference.
Thanks
db

[madjack181]

PS,
While this is going on I'm not getting a Trans Warning light.
db

[Jeron]

My guess would be electrical. The E46 tranny uses M to indicate Manual mode and M(1-5) indicate a driver selected gear. This sounds like what you are getting, where the S is sport mode.

I wish had better advice but all I can suggest is to look for bad wires or connections at the shifter and at the tranny.

[madjack181]

Well,
I fixed the problem, and after doing some research I found this sort of thing is not unique. Also, I'm not the first that has had the events that lead to the problem.
First of all, what triggered the problem was a trip to the car wash. (This is my daily driver so I'm not too particular about this task) Anyway, it is one of those do everything type that even sprays the underside of your car as your pulled through. The high pressure wash on the bottom wreaked havoc on the wiring.
The source of the problem was the wiring to the gear select switch on the drivers side of the transmission. After 10+ years, the insulation around the wiring had become brittle and the high pressure wash had blown the insulation of in places leaving bare wires touching.
There isn't a lot of wire to work with so I spread the wires apart and doped on a generous amount of RTV. I also disconnected the canon plug, cleaned the connector with contact cleaner and then sprayed some silicon on the connector.
everything now works great. If it crops back up I'll have to look at replacing the switch.
Cheers
db