Excuse me if I'm asking too much, but since I'm a new owner of an old Volvo new stuff keeps coming up.

So my cruise control is not working like it should. At first I thought it didn't work at all, so I pretty much dismissed it as a project I wouldn't take on anytime soon. But after fooling around for a bit I found out that my cruise control work in a strange way.

This is what it does: If I turn it on and hit the set/+ button you can feel it catch on, but it turns off right away. Now, if I turn it on and hit and keep holding the set/+ button the cruise control will kick in and keep the speed for as long as I keep the button pressed. As soon as I release the button it will turn the cruise off. This seems to be absolutely consistent, and it works every time I try it, and it holds up for long distances too.

So my assumption is that the vacuum pump and hoses probably works as it should, but something is wrong with the electronics. To me it sounds like maybe the switch itself is bad, but I thought I'd pick the brain of you guys before I start replacing it. Any other Ideas? Could it be the control module, or maybe even the brake switch gone bad?

 

Most likely a hole in a line somewhere.

 

Thanks Tech,

this is probably me not knowing a lot about cruise controls, but why does it work when I hold the button? It just sounded more like an electronic / connection issue than a vacuum issue to me...

 

Well when you would hit the button the motor will keep running. But when you let go the system should stay in vacuum. With a leak it will not stay.

 

Ok, that makes sense...

I found another post about vacuum leaks, so I'll go ahead and read that before I ask questions others probably asked before.

Thanks!

 

The cruise control uses its own vacuum pump that is distinct from the engine vacuum. What year is your car? If it is a '93, '94, or '95 you can run the system through a series of tests to track down the problem.

...Lee

 

Yes, I became aware that it is a separate vacuum pump when reading other threads on this forum. It's a 94 and I did stumble across a pdf with test procedures that was linked from some forum thread. It was pretty long though...