So, I bought the 89' 240 wagon a few weeks ago and I replaced the battery, had the alternator tested, put new belts on it because the old ones were wrong and worn out. I could not get it to start, so traced it back to the fuel pump fuse. I cleaned the fuse holder and replaced many of the older fuses. It started and ran for a few days, then the dash lights went out. I traced that back to a loose wire for the seat belt connector light. Dash lights work fine now. I have driven it for 10 days and even went up to the mountains (100+ miles) and this morning the radio goes dark, the dash lights go out and ther is some buzzing and clicking behind the climate controls. I pull into work and the car dies. Hazard lights are weak and the car won't turn over. I check the fuses, all are good. I check the connections on the alternator, all good. I check the battery connections, all good. I get a jump start and the car fires right up. Dash lights are on, radio lights are on and all seems well. I know that electrical problems are difficult to troubleshoot over the internet, especially intermittent ones. But does any one have any idea where to start looking for a problem such as this?

 

How old is the alternator?

I would pull the regulator out of the back of the alternator and inspect it (also known as the brushes)

Most of the time when they are going bad at night you can see the battery light on very dim. Also they can give problems when they get hot.

 

It sounds to me like you have a short somewhere. To find it first pull the fuzes to the clock and the radio. Then take off the neg side of the battery and touch it to the terminal post. If you get a small spark you still have something draining the battery. Pull the fuzes one by one until you get no spark. The fuze that you pull that stops the spark is the one with the short. They can be hard to find. Good luck.