This video shows how to use and some basic trouble shooting for the cruise control for the Volvo 850, S70 and V70.

 

Thanks for the video. I'll start with the brake switch, vacuum lines and gas pedal rod. I already replaced the relay, no luck.

 

Great video, as usual! I'm going to check all the points you suggested to see if I can convince my cruise control to work again.

Questions: Does the cruise control have a switch on the clutch for the stick shift cars? If it does, where is it and how should I check it?

If the clutch does not (I suspect it doesn't, because I can start my car with the clutch out and even in gear!), what would happen if I was using the cruise control, pushed in the clutch, and shifted into neutral until the car slowed down? Would my engine rev madly?

 

Not sure about the manual cars. I'm sure Volvo would not have designed a system that would allow the motor to rev when put in neutral.

 

One thing I've wondered about..

My 97 has working cruise, but it has a strange feel to it.

What I mean by that is this: when I'm going down a hill, with the cruise on, I can feel it holding the car back hard. Not like any other car I've ever had. It seems to work smoothly in the acceleration department, but on the odd occasion where it tries to hold the car back, it just feels unnatural when compared to other vehicles I've owned.

 

I would assume it is cutting the throttle and staying in gear to use engine braking to keep the car at a steady speed going down hill rather than just letting it coast way faster than the speed it is trying to maintain.

 

Try switching the performance button to E or S.

 

Well, I finally got around to tinkering with the cruise control and found the problem. Bad vacuum line under the battery tray. I cut out the damaged section and slipped on a length of windshield washer hose to patch the line. Works great! Thanks for the advice. Much appreciated.

 

On manual cars the switch is the same as the one on the brake pedal and also located in the same area.

 

Mine does the exact same thing, according to my trip computer it is shutting off the injectors. My fuel usage drops to 0 litres / 100km when it does that.