Electrical Saga Contiunes

[cavalry13]

So for about the last month I've been trying to figure out what has gone wrong with my 1993 325i. I originally thought that my alternator was going but now I'm not so sure. While on a trip to a Portland, Oregon which is about 200 miles from where I lived it drove just fine till about one mile from where I was going and all of the sudden all the lights started going dim and the all sorts of warnings and lights came on. The 325 also seemed to drop into an emergency transmission mode where it still ran but if I tried to accelerate it wouldnt go faster it would just continue to limp. When I got to my destination I swapped out batteries which seemed to solve the problem for at least the short term. Thinking that it might be an alternator issue I got my car home charged up the battery and it started right up. I left it running for about four hours while sitting in my driveway and it just ran and ran, no loss of battery power or nothing. Now this morning when I went to do some trouble shooting it wont start. It acts like it has a dead battery even though a check of the battery shows its at 12 volts when not running. I'm at a loss, has anyone seen this kind of behavior before?

[David Mc]

Checking battery voltage whilst it is not under load doesn't tell you much. Try checking while someone is trying to crank the engine and if it's less than 10 volts it will be flat. The problem does sound like an alternator fault and the reason the car will run whilst it's sitting in your driveway is that the alternator output is low (so it just punches out enough to keep the car running, but not to cope with any other load). Try turning on the radio, fan and headlights and leaving it to run in your driveway and I think you will find the car will stop after about 20 minutes on a charged battery.

[JetBlack328i]

take the battery to a parts store and have them check it too. They should be able to check your Altenator too at the same time.. Those would be my two guesses as to what the problem is.