The cruise control buttons on my 3.0 v6 S-type didn't work. Neither the up, nor the down. I was going to replace them, but thought it likely that any used items may have the same problem.

So I unhooked the battery, removed the airbag and removed the switch assembly. It turns out that you can remove the rockers using a small screwdriver as a lever. After removing the rubber pressure pad, you can see the electrical contactors. These too can be removed using a jeweler's screwdriver. Covered in tarnish, it was no wonder they weren't working.

A small amount of kitchen hob cleaner, a rag and a screwdriver were used to clean all of the contacts. While I had the airbag off I did the same to the volume switches on the other side of the steering wheel. Once everything was reassembled and battery reconnected, hey presto! It works. I now have cruise control and volume control again.

Woohoo! That's £25 saved. Which is what the cost of a brace of used switch assemblies would have cost.

 

Nice one!!
I have known it said that issues with these switches can be caused by the excess use of silicon type dashboard cleaning products, combined with a lack of use.
How true that is I have no idea.

Mellow

 

My car's cruise didn't work when I got it. I hoped lack of use so just kept trying - which after a while worked!

 

How buried are these contacts? Would it do any good if I sprayed some plastic-safe electronic cleaner into the edges of the switch while still installed? Or is removal and disassembly the only reasonable plan of attack?

 

They are buried. I doubt spray would work. Yes disassembly is the only reasonable plan of attack. It's not too hard to do if you have a spare hour or so, some small screwdrivers, and something slightly abrasive like hob cleaner or t-cut.

 

When I got my STR the volume buttons didn't work (steering wheel) so I had to clean them. I doubt a spray would even reach the contacts without taking the buttons apart.