Had a unusual problem on my wife's 91 940 last night, and could use some information. I was changing the oil and checking things out while listening to the radio. I had been draining the battery pretty good and when I went to crank the car, it wouldn't start because the battery was low. I hooked up the charger and after a few minutes was able to crank the car. While it was idling, I put the multi meter on the battery and all I could read was about 10 Volts. I turned the engine off and noticed that none of the dash lights were working (battery charge, oil light, check engine, etc.). It was late, so I went to the house and started looking for a replacement alternator. After thinking about it, I realized that the charge light not working was probably a indicator of something else causing the no charge condition, and planned to check it out this morning. I wen't out this morning, turned the ignition switch and Behold!...all of the dash lights were working. I cranked the car and sure enough, the alternator was charging (14V). What happened overnight? I'm not familiar with the 940 electronics, but I suspect it has something to do with the charging circuit in the dash. I know that the excitation voltage for the alternator field comes thru this light, but the bulb is good, it just doesn't work all of the time. Where do I look? Any help is appreciated.
steve