Cruise not wanting to disengage easily.

454cid · Post by **454cid** » 12 Feb 2022, 02:36

Something, I've noticed about the Volvo is that the cruise doesn't disengage as easily as I'm used to. My GM vehicles, I can breathe on the brake pedal and it disengages cruise. The 850 seems to require a much more deliberate action, and tonight was the worst I've experienced.

Doing a search, I see Volvo used a separate switch on the pedal, and I also find a vacuum line reference.

I have not looked under the dash yet... it's currently 4;30am so it'll have to wait until "tomorrow" during the day.

Otherwise cruise works fine.

Is this common behavior for the cruise control, and what can I expect to need attention?

Post by **abscate** » 12 Feb 2022, 02:40

It’s connected to the brake light switch and it sounds like it needs attention. There is some adjustment ability , I’ll try to find thread

In 1999 , it’s all electronic and instant. That’s why Prince wrote a song about that year

454cid · Post by **454cid** » 12 Feb 2022, 20:31

It was only about 20F today and I only looked at the car enough to find that the underside of the dash is completely covered.... I did not know that until today.

Post by **erikv11** » 12 Feb 2022, 21:58

So the day was a success!

I agree sounds like cruise disengage on the brake switch needs a look, there is a vacuum release there. Cruise on the P80 cars is a little crude e.g. doesn't hold speed that well going up big hills but the brake switch should be sensitive.

454cid · Post by **454cid** » 12 Feb 2022, 22:41

erikv11 wrote: ↑12 Feb 2022, 21:58 So the day was a success!

I agree sounds like cruise disengage on the brake switch needs a look, there is a vacuum release there. Cruise on the P80 cars is a little crude e.g. doesn't hold speed that well going up big hills but the brake switch should be sensitive.

I did notice that speed doesn't hold as well as my Saturn. I do like that the Volvo sets much faster than the Saturn, However. The Saturn would always wait to take over, then slow down a bit, and then set slightly under where I wanted it, which was super annoying. The Volvo takes over right away, which is a big change for the better. I don't really have hills on my way to work, so the holding the speed isn't a big deal for me.

I do have a vacuum line that is disconnected from someplace on one end, under the hood. I wonder if that's affecting it. I'll have to get a picture up.

454cid · Post by **454cid** » 12 Mar 2022, 11:22

A new brake light switch fixed this problem. Cruise disengages very well now. What's the other switch, and vacuum parts on the pedal do for cruise, if the brake light switch is what disengages it?

Post by **abscate** » 12 Mar 2022, 12:50

Isn’t the vacuum can under dash pulling on the throttle to work the cruise control on -1998 cars?

Is it too late to crack about Saturns and their rings?

454cid · Post by **454cid** » 12 Mar 2022, 12:57

abscate wrote: ↑12 Mar 2022, 12:50 Isn’t the vacuum can under dash pulling on the throttle to work the cruise control on -1998 cars?

I have no clue how it works. I'm used to cruise mechanisms being under the hood. There is a vacuum diaphragm mounted around the brake pedal, unless being upside down skewed my perception and it's actually on the gas pedal.

I'm really happy this switch fixed both issues.... too bad the switch is so expensive, and apparently prone to going out.

Post by **erikv11** » 12 Mar 2022, 19:53

Cruise control operates via a vacuum pump located under the battery tray. Vacuum line runs through the firewall to the bellows, which operates the gas pedal to control the throttle plate. The switch on the brake pedal shuts off the vacuum pump.

The brake switches actually don't go out that much - not a high failure item on the forums. Good junkyard item for that reason.

454cid · Post by **454cid** » 13 Mar 2022, 01:49

erikv11 wrote: ↑12 Mar 2022, 19:53 Cruise control operates via a vacuum pump located under the battery tray. Vacuum line runs through the firewall to the bellows, which operates the gas pedal to control the throttle plate. The switch on the brake pedal shuts off the vacuum pump.

That seems odd to me, that Volvo brings control back into the car to operate the foot pedal.

The brake switches actually don't go out that much - not a high failure item on the forums. Good junkyard item for that reason.

Maybe I've got something going on that takes them out in my car? My car has less than 100K miles, and the one I just replaced was not factory Volvo, which means the car is now on it's third switch.