I'm new to the forum and to Volvos. I purchased a used 1990 Volvo 240 for my son's first car. When I test drove it and for a few days after the purchase there were no problems, but then I started to notice things. First, therear running lights were not working and then they would, then the passenger's side window wouldn't work, then it would, and sometimes the radio doesn't work, then it does. I was mostly concerned about rear lights so I've concentrated on that. I did find that the running light on the rear left wasn't making connection with the circuit board, so I purchased a new tail light with a new board. Now the running lights work fine, but the break lights (left and right) work sporatically (the center light in the rear window works fine) AND only when the running lights are turned on. When the running lights are off, the break lights work fine. Any thoughts would be greatly appreciated.
Karen.

 

I would make sure all the connections for the tail light plug are clean and tight.

For the other electrical issues I would remove all the fuses from the fuse panel and wire brush the panel and install new fuses if you can.
Try using only the brass fuses the aluminum ones corrode alot.

 

Have checked the connections at the lights both the plug and the ground wire. Wiggled them as well and nothing changes the behavior. When the running lights are on, the break lights (left and right) don't work. When the running lights are off the break lights work fine. The middle break light in the back window works regardless. I've replaced the left rear tail light because the circuit board wasn't making a good connection for the running light. That running light works like a champ now, but since putting in the new light is when the break issue seems to have started.

 

OK up under the dash on the drivers side like right by the steering column is a round red relay it is the bulb failure relay.
You can open it up and check the solder joints. They are known as well to cause problems.

 

Couldn't find it, butI thought that if the relay went, there'd be no lights at all. The break lights work fine with the running lights off and the break light up in the rear window always works regardless of whether the running lights are on or not.

 

The failure realy is a wacky relay.
There is a metal bar that the steering column screws to feel around there it is supposed to be clipped to it.
Most of the time someone takes it out and never puts it back.

 

Dumb question... what bulbs are you using in the running light and brake light slots? 1156? 1157? They're numbered right on the bulb

 

I've had several older Volvos and learned after the first one that the best thing to do with a new-to-you car is replace every bulb, making sure to use the correct size. It's also good to pull off each wire and put a little de-ox gel on the connector. You can buy it at any auto parts store for as little as a dollar. Often just due to age and wear, the wires can get loose and/or corroded. Also the metal contacts on the bulb holders can get bent slightly, causing the bulb to malfunction or work intermittently.

 

This problem is solved. Through a lot of troubleshooting from stem to stern, top to bottom. It turns out that the two sockets for both running lights/breaks had problems with their ground connection.As it turns out, the breaks were on when the running lights were on rather than not working. One was just old and worn out, the other that was new just didn't make the connection properly. Once replaced and altered, they now work beautifully. It really had us thrown because both had the same problem at the same time with two identical but unrelated sockets.

 

Glad you found it and fixed it.