I have a 98 S70 base model with about 190k on it. What happened was that the car was operating normally when out of the blue the turn signals started clicking in double time, which typically means there's a bulb out. I checked everything over, the bulbs appeared fine. Well it kept getting more erratic, sometimes it was double time, sometimes it was normal, etc. Then eventually it hit the point where I'll hit the left and right turn signal and both times it puts the flashers on and my rear turn signal as well as my rear reverse lights went out. My cruise control apparently is no longer working either. There will also be random times when the signal blinkers will just come on: for example I may turn the car on and my left blinker is solid green and nothing changes if I turn the left, right, or no signal on; then it may randomly turn off. What usually happens is that I'll hit it and it will do the flashers in double time, but it's hard to predict and I'm really lost.

At this point I have replaced:

All fuses on related to the lights (they all looked fine, but checked over the connections and replaced them anyways).
All rear turn signal and other backup bulbs
The flasher relay under the radio.

All connections etc. were checked as well as the front turn lights, and they all appear fine.

Any idea what is left causing this? I've asked other volvo owners I know, gone through all the seemingly obvious stuff, looked at electrical diagrams, etc. I'm curious as to if this is something I can just get a part for and handle myself, if I need to take it somewhere, etc. I'm afraid it's something in my steering column and really can't figure out anything else unless there's something glaring that I'm missing. Aside from these little issues the car runs tip top.

Any and all help is much appreciated.

 

In most of these cars the flasher switch is the control relay for them. Besides that, you may want to check the bulbs for grounding out. The S90/960's have a common issue that are due to the turn signal bulbs going bad and grounding themself out. They still come on but wreek havock on the system.